COLLAPSED PISTON [Archive] - Bulltear Pro-Parts Forum

1980_Cj7

08-27-2006, 05:53 PM

Yes, we're going to be talking to the machine shop and Ross tomorrow. Funny thing is now I can't find anything on Ross Racing Pistons on fastengineparts.com (maddog) where we got these. Although it says Ross pistons are available under the Master Engine Kit listing for AMC 401 Performance II, when you click on Pistons, then the Ross link, it just says

"Found (0) Makes.

We are sorry, Your search did not turn up any makes under this category. Please try another search."

When I get on Ross's web page, I'm not finding any AMC pistons listed. We just got these a couple months ago.

AMX69PHATTY

08-27-2006, 11:03 PM

Yeah I got the same search results for AMC Ross Pistons on the FastEngineParts web page. They do have them listed on eBay though within thier eBay Store. Guess they don't keep thier standalone web page upated.
:-|

The Pistons are lubrictaed by Oil coming from a squirt hole in the connecting rod from the oposite bank. If the scored piston is #7, then it would be lubricated by the #8 Connecting Rod squirt hole. The squirt hole is in the seam between the Cap and the Rod. Was the #8 Connecting Rod installed turned the right way ? If it's turned over the wrong way, then the squirt hole is not facing in the direction of the #7 Piston.
Just a guess. :-|

Also, if the rods are reconditioned, it's possible that the squirt hole was eliminated because the mating surfaces of the Rod and Cap are machined to egg shape the rod journal hole so it can then be made round again. If I remeber correctly, this is why there is a hole in the rod bearings at the mating edges so oil can escape and feed the squirt holes.
Just another guess. :-|

1980_Cj7

08-28-2006, 05:38 AM

I'll have to look at all that tonite. I did notice that the top half of the No. 7 rod bearing seems to be wearing more right in the middle rather than evenly over the entire length.

82Waggy

08-28-2006, 05:56 AM

The piston does not appear to be galled above the oil ring, and the wrist pin end of the rod looks to be discolored from heat.

What does the top of the piston look like?

I'd bet it got hot and expanded too much for the bore clearance. The top of the piston probably stayed a little cooler from the intake charge.

tufcj

08-28-2006, 06:35 AM

Call MadDog's 800 number, ask for extension 113 and ask to talk to D.W. He's their AMC guy.

Looks like the block was bored without enough piston/wall clearance. Looks like the piston expanded and galled itself on the cylinder wall. There should have been a spec sheet that came with the pistons that should have had the piston diameter specs, and the necessary clearances. Your machinist should have worked from that to determine final bore diameter, not just a standard .030" over stock.

I have Ross pistons from Mad Dog in my 69 390. They are a high quality piece.

Bob
tufcj

1980_Cj7

08-28-2006, 07:15 AM

The top face of the piston looks fine, and just like the rest of the pistons.

Engine was definitely not overheated, and was shut down when the knock started. We paid particular attention to cooling and upgraded to a FlowCooler water pump, used a 165 degree thermostat, and installed an electric fan with an adjustable controller.

Yes, the detailed multi-page instruction and inspection booklet that came with the pistons went along with them to the machine shop. Looks like they looked at them because they came back with some grease on them. I was quite impressed with the Ross pistons when we got them by the amount of inspections they are subjected to. I'm no piston expert or anything, but they appeared to be good quality.

A question for you more experienced and knowledgeable engine builders, just how do Ross pistons rank among other brands? There isn't a whole lot of choices out there for AMC's, especially in the compression ratio range we were shooting for.

82Waggy

08-28-2006, 09:39 AM

You can get locallized overheating on just one piston for a short time without overheating the whole engine.

Ross pistons should be fine. Other custom makers include JE and Venolia, among others. Tolerances should have been checked for bore clearance at assembly - matching each pistons to its' designated bore.

I'd say this one either had a bore that was a bit too tight, was dirty, or overheated due to a localized problem.

Your previous posts talked about the amount of advance you were running - this may have been too much for ole #7. Not all cylinders fire exactly the same so you must set the maximum advance not to exceed the most detonation prone cylinder under worst case loading conditions.

For the compression you are running and the use of pump gas, I would say you were in excess on timing. A 14deg base setting is usually plenty for most street engines, assuming a proper mechanical curve and vacuum properly limited so as not to cause detonation at part throttle loads.

With vacuum advance reconnected on a 20degree base setting, advance at cruise loads (off idle) may well have been too high.

I think you said you had the vac advance hooked to ported vacuum on the carb. If the carb was adjusted properly, you should have had no additional vac advance added to the base setting at idle. As soon as you touch the pedal advance would go as high as the can would allow and then only decrease as vacuum decreased to wide open throttle.

Of course, at low vac wide open throttle conditions vac advance is at its' lowest and mechanical advance is all there is.

10:1 static compression is usually consider high for pump gas and iron heads as well, but detonation is more dependent upon dynamic compression (when the intake valve closes on the upstroke and compression actually starts building). If you happen to be running a cam that is intended to increase dynamic compression in engines with low static compression (intake valve closes earlier), cylinder pressure could go through the roof.

1980_Cj7

08-28-2006, 10:10 AM

We first set the timing at 10 degrees, and the old tired 258 would have run circles around it at that setting, so we advanced it to 15 degrees, and that is the highest base advance the engine was run at. At 15 degrees base, we were getting 35 total at 3000 RPM's.

We still didn't feel we were getting the power we should out of the engine, and talked to the machine shop/engine builder. They told us to set the timing with a vacuum gauge. They said to advance the distributor til we got the maximum vacuum reading, then back it off 2". They said this was the optimum timing for an engine.

When we tried that method. We got 17" of vacuum, and backed it off to 15", then checked what we had with the timing light and got 20 degrees. The engine wasn't run at that setting though other than idling long enough to check the timing. It just seemed like way too much timing.

The engine did turn over normally though at 20 degrees, and started right up, whereas at even 15, it struggled to turn over, but did start quickly.

82Waggy

08-28-2006, 11:35 AM

Well,

Maybe timing was not a factor, but it seems the total advance with vac connected was not known and may have been too much at part throttle high load conditions. I think the stock distributors were curved for a base timing of around 10 (+-2) degrees.

Anyway, will be interested to hear what the piston to wall clearance was on this cylinder.

Are the other rods discolored at the wrist pin like this one, and are they pressed pins or full floating?

1980_Cj7

08-28-2006, 12:37 PM

I'm not sure No. 7 is even discolored. I'll have to look at it closer tonite. Might just be the picture. Didn't really look at any of the others either.

The pins are "pressed in", not floated, but the shop has a rod oven and heats the rods so the pins "drop in". Maybe that caused the discoloration if it is truly discolored, but I wouldn't think they'd have to heat them that much to expand them to get the pins in.

I did notice that the pin on No. 7 isn't exactly centered side to side in the rod, but don't know that that would make any difference. The pin is still well recessed within the piston with the rod centered on the piston.

jeepsr4ever

08-28-2006, 04:07 PM

Yes the discoloration is from the heat they used for getting the pin in there. Was their 4 areas on the piston that showed scoring? Do you have any pics?

tufcj

08-28-2006, 06:02 PM

What does the top of the piston look like? You could have had some serious detonation causing the piston to bounce around in the bore.

Bob
tufcj

1980_Cj7

08-28-2006, 07:01 PM

Looked at the small end of the No. 7 rod again. It is slightly discolored, but I think I see why. Looks like the shop did some grinding on it, probably as part of the balancing.

Here's some more pics. The top of the piston didn't look any different from any of the others when we pulled the head. It looks different now because we were wiping at it. The blackness comes right off and the piston is perfectly smooth underneath, not pitted or anything. See that one real shiny spot where I picked some away with my nail.

I don't know if the pistons are carboned up from the shop running it with the plug wires pulled, or from us experimenting with the carb tuning. Somebody mentioned it was maybe leaning out, but the tailpipe is all sooted up, so I think to the contrary it was running rich if anything. We had just switched to some colder plugs too right before this happened, and when we pulled them they were all black and carboned up, so I think that was a move in the wrong direction.

And the piston is only scored on the upper skirt side. Here's a pic of the opposite skirt.

https://home.comcast.net/~rwsr50/ComcastOnlineStorage/BadPiston_003.jpg

https://home.comcast.net/~rwsr50/ComcastOnlineStorage/BadPiston_008.jpg

https://home.comcast.net/~rwsr50/ComcastOnlineStorage/BadPiston_009.jpg

jeepsr4ever

08-28-2006, 07:26 PM

Looks like you definately got heat from the top. Are they really early Ross's? I have heard that early Ross pistons yeilded some rather high compression ratios. I wonder if your camshaft isnt dialed in right. I would check the timing gears and see where you are at.

1980_Cj7

08-29-2006, 03:00 AM

I remember checking when we were putting the timing cover on. The two round punch marks on the timing gears were lined up with each other, the cam one at 6 o'clock, and the crank at 12 o'clock, and the timing mark was on TDC.

Yes, they are Ross pistons. I don't know about early or late. I can pull up the exact data that I forgot and left at work, but IIR, they were manufactured about a year ago according to the paperwork.

That brownish color on No. 1 piston and the block in the pic above is just the lighting. They are all the same, black.

What are you guys experience with the highest compression ratio that will still run pump gas?

Blown7

08-29-2006, 04:36 AM

For some reason I'm beginning to believe that MC may have a good thought process going here, and with your previous posts on your timing troubles Did you set up your cam timing this way or just "line up the timing marks"
Also where your heads reworked? Were the chambers CC'd? You may have a different compression ratio in that cylinder.
http://i25.photobucket.com/albums/c96/Blown7/newpicjune10037.jpg
BTW I find with some cam/timing chain - sprocket sets that use multiple keyways that you have to use whatever keyway slot combo's that give you what you need, not just slapping the timing set on and calling it good to go.

Jeff

1980_Cj7

08-29-2006, 05:19 AM

OK, the Ross pistons have XL408 cast/forged into the underside of the top, and the inspection dates on the paperwork are 1/26/05 and 2/10/05. They have a .145 dish depth and are -23 cc's.

The heads weren't reworked other than new valves, springs, etc. and a valve job. They were milled just enough to true them up. They weren't CC'd that I know of.

Blown, I can't view pics from where I am now, but I'm guessing your pic shows a degree wheel. We didn't set up the cam, the engine builder did. They just put the timing cover on loosely with a couple bolts and no gasket, because, as you know, a lot of the timing cover bolts go thru accessory brackets, water pump, etc. When we pulled it to install the gasket and finish off the assembly, I checked the timing marks, but didn't put a degree wheel on it.

Yes, our timing set had three keyways for advanced, retarded, and standard timing. Before sending the parts to the builder, I did some checking, and I had to open up the divet on the gear as it didn't line up with the hole in the cam journal, so I'm wondering if the keyway/s might have been off too. Now I'm thinking. We got the engine kit from fastengineparts/maddog, and although they advertised a Cloyes timing set, when we got it, it was an S.A.Gear timing set. I called them on it, and they claimed it was much better quality than the Cloyes. It was made in the USA, Los Vegas or somewhere if I recall.

The engine builder was good enuff to offer to come by our place tomorrow night and check things out so we don't have to hassle with getting the Jeep on the trailer with it not running, and haul it around with the engine hanging open. We'll see what he finds when he does some measuring. We'll ask him about the cam timing.

Holeshot

08-30-2006, 04:17 AM

Something else to consider is that cyl 5 & 7 plug wires run next to each other & fire in order, so detonation on 7 is always something to beware of & you HAVE to have those two plug wires seperated as much as possible.

The pin end of the rod looks like it got very hot, full-floaters are mandatory in a hipo engine. Does the piston still swivel on the rod well?

Any chance that coolant got in there while running?

Also looks like the two oil ring rails are pretty much lined up, not good practice. If that is an example of the build quality, you need another builder.

I'm betting that detonation due to WAY too much piston to head clearance, plus the error of using pressed pins, plus the possibility of crossfire from 5 to 7 caused this failure. Do you have loud exhaust that would inhibit your ability to hear pinging? How high were you revving it?

Something amiss in the machining, assembly, or execution here.

1980_Cj7

08-30-2006, 06:17 AM

The wires are removed now, so I can't check, but I "think" we had them pretty well separated.

The piston is very free on the pin, both rotating/swiveling, and side to side. Can't "feel" any slop in it though.

I think the discoloration on the small end of the rod may be from either the oven they used to install the pins, or grinding evident on the end of the rod that was probably done as part of balancing.

No coolant got in.

I noticed the ring gaps not being offset too and am going to question the builder about it. I'm no engine builder, but even I know the gaps are supposed to be offset, and by a specified amount.

I'm not sure there is excessive piston to head clearance. It's easy to see and check right now though. The pistons come up almost flush wth the top of the block. What should the measurement be and where do we check it? I do have a digital caliper and should be able to get a fairly good measruement on something like that.

We asked about floating the pins, but were told for what we were doing with the engine, there wouldn't be any advantage, and that it would be very expensive to do.

The highest the engine was ever revved was probably 4500 to 5000, and only for a very brief shot.

AMX69PHATTY

08-30-2006, 08:09 AM

Whatever happened it's a real bummer to have gone through all the work and espense
and have it go south, especially a fresh thumpin' 401.
Any discoveries on the Connecting Rod Oil Squirting Holes ?
Piston to bore clearance for Forged pistons is looser than Cast.
Per Performance American Style, Forged = .006 to .009, Cast is .001 to .002.
This is the clearance on the diameters.
May I ask the clearance listed on the Ross spec sheet ?
Has the #7 bore and piston from the motor been checked yet ?
What a bummer. Hope you determine what caused it.

Holeshot

08-30-2006, 08:18 AM

Another odd thing that may have happened, bearing in mind that you said that your old 258 could have run crcles around the 401, would be that instead of a firing order of 18436572, the dizzy wires got put on 18436752, making the #7 cyl preignite EVERY time & the #5 cyl to fire while the piston was midway on the downstroke of its power cycle. Just grasping for answers...

1980_Cj7

08-30-2006, 08:59 AM

Didn't check the oil squirting holes yet. Maybe tonite.

The Ross spec sheet that came with the pistons is calling for .004 the way I'm reading it. There are 2 sets of instructions, "A" if the piston has a step at the corner under the bottom most ring, and "B" if it is radiused. Our piston is radiused, so here's what the "B" instructions say:

Normally aspirated street cars
Bore size 3.475 and under - .003
Bore size 3.476 to 4.499 - .004
Bore size 4.500 and above - .006
Modified type engines, including drags, circle track, and road race - .004 to .005
Turbo engines, small bore - .006
Marine applications add +.002
Nitrous over 250hp V-8 add +.002
Nitrous over 100hp 4 cyl add +.002

There is an interesting note however that engines which have been honed without torque plates will require addtional clearance. I just added another question to my list for the engine builder, "Did they use a torque plate?" If they didn't, and didn't allow the addtional clearance, that might explain the problem. Plus, if they didn't use a plate, the bore would be more likely to be out of round wouldn't it?

My son and I checked and double checked the wires and even had a wiring diagram in front of us showing the correct order, so I'm certain the wires were right. Plus, the engine ran too smoothly to have had them crossed.

Thanks guys for all the help and concern. Believe me we are really bummed out after all the work and money. I'm just hoping and praying this engine can still be salvaged.

Goose

08-30-2006, 10:13 AM

I just went back and re-read all your posts and info..If that Galling is on the" top side" (I'm guessing toward the intake manifold) then the odds that this was caused by Detonation/crossed wires or anything to do with the power stroke is small. since that would normally appear on the bottom side of the skirt..(IF you think about it a minute the explosion forces the piston down.) so my guess would be it is a clearance problem or oiling..
Especially when you take into account it happened in 300 miles.

I finally remembered where I had seen that pattern of galling before. In the bad old days when Yamaha in thier infinite wisdom brought out the first watercooled 125 works bikes. we had a problem with "Cold sieze" when you started the bike if you touched the throttle at all. the piston expanded faster than the sleeve and bang! it siezed up! which resulted in pistons that looked very similar to what you have here.. so Im curious to find out what the bore/piston clearance was and is the the bore actually round.

KJMac

08-30-2006, 11:08 AM

82Waggy

08-30-2006, 11:24 AM

Yup, I think it was too tight myself - maybe some dirt.

Most non-AMC builders do not have a torque plate. I had to custom order one from BHJ for my two projects.

I also have considerable experience with the cold seizure issue on small engines and your piston does look just like that problem. Skirts start to stick first as the piston head stays cooler from the intake charge.

Most people also do not realize that you need to let a forged piston engine warm up good before you lay on the power - otherwise the block does not expand as quickly as the piston.

It also looks like you were running rich to have that much soot build up already.

1980_Cj7

08-30-2006, 11:38 AM

Yes, agreed that we were running rich. We were working on carb tuning and plug heat ranges, with Fuzz as a matter of fact, trying to get that straightened out, when we had to quit due to the knock showing up.

Hmmm, maybe I'm on to something here. I wonder if Fuzz sabotaged our engine so we wouldn't blow his doors off??? No, wait a minute, that couldn't be...he ain't go no doors! Some ricer already must have blown them off.

Goose

08-30-2006, 12:43 PM

Well I hope ya get it figure out.. and poke the holes looser(Sorry couldnt resist) cause as we all know theres chevys and fords and even a few mopars out there but none of them sound like an AMC doin what its best at..(Sorry here you have to imagine a Trosley drawn AMX and a CJ smokin off into the sunset goin "WAAAAAAAH"

(To anyone who doesnt know who George Trosley is that last deal wont make a bit of sense).

1980_Cj7

08-30-2006, 02:29 PM

Yes, ours did sound REALLY good, the short time it was running. Even Fuzz commented on how good it sounded, and I consider that a real compliment coming from him.

AMX69PHATTY

08-30-2006, 03:43 PM

Yep, a torque plate insures cylinder roundness.
When the head bolts are torqued they cause some distortion in the cylinder walls.
So cylinders honed round without a torque plate can be out of round when heads are installed.
Using a torque plate on the block while honing prevents this by introducing
the same stresses in the block as will be there when the heads are torqued down.
I've been told machine shops hate AMC Blocks because they wear out there boring tools
due to the fact that AMC blocks have high nickel content and are very hard.

1980_Cj7

08-30-2006, 03:47 PM

I have heard the same thing about the AMC blocks being hard and wearing real good. I hope it is true and our No. 7 cylinder isn't ruined.

I just came in from checking, and the oil holes in the rod caps are all to the inside.

Holeshot

08-30-2006, 06:53 PM

why don't you take the rings off another piston & stick it in it's bore & see how much clearance ya have so we can all take another breath?????

1980_Cj7

08-31-2006, 05:41 AM

1980_Cj7

08-31-2006, 06:57 PM

OK, the engine builder made a house call tonite. Just before he arrived, we pulled piston No. 1. It was starting to show signs of wear in the same place as No. 7. The builder was really stumped. Said he never saw anything like this before. He said the wear is always on the bottom side of the cylinder, and at the very ends of the piston skirts. He said the pistons are tapered, and showed us that the pistons measure .004 bigger diameter at the ends of the skirts, than they do in the middle. He demonstrated this on the piston that wasn't worn.

He measured the cylinders, and said they are in spec at .004 over the piston size. Luckily the cylinders, even the worst one, No. 7, didn't measure out of round, even where the piston was rubbing.

He said he didn't use a torque plate, but that with engines this heavy it wasn't necessary. He claimed you only really need them on thin-walled engines like 302's.

So, while he was here, we pulled the other two pistons, and guess what, they were worn just like No. 7, but hadn't progressed as far. So, we thought there might be a pattern to the wear, getting worse the farther back the engine you went. That didn't hold out though, the order of best to worst was 1, 5, 3, 7.

The builder looked at everything, head, valves, lifters, pistons, rods, bearings, etc., and said that everything looked fine and normal except for it running rich and being carboned up. I mentioned that some of you noticed the discoloration on the small end of the rod. He looked at it and said that was normal and was from their rod oven, and that if it was from overheating, the pin would show discoloration too.

So, he, and we, are basically stumped. He recommended we pull the other side apart and see what we find there. I asked if he thought Ross might be able to provide some insight, and he said we should send them pics of the pistons and see what they think. Said we might even want to send them some pistons to check out.

The pistons do have offset pins by the way, but with the way the valve pockets are cut, it would appear they can only go in one way. Or, could they be switched from side to side??? I have to think about that one a little.

I'll get some more pics of the wear on all 4 pistons and post it, but right now I'm too disgusted to look at it any more tonite. The only good news is that the block is salvageable...at least so far. We haven't looked at the other half yet. There no sense putting anything back together though until we figure out what caused it, and what to do to keep it from happening again right away.

The builder didn't have anything along to measure the deck height. I tried my best to measure it with my digital caliper, and was getting less than .045. What effect would that have, other than valve and piston interference, which there is no indication of. The builder mentioned something about quench, and less deck height giving more power and allowing more timing advance, if I understood him right.

82Waggy

08-31-2006, 08:36 PM

Good quench results in a more specific combustion event and therefore allows you to back off on timing advance, thereby reducing negative action on the up-stroke of the piston. .040 - .050 piston to head clearance is a good quench distance.

I'd say .004 P:W clearance for a forged piston is too tight for a bore that was not honed with a torque plate. Any distortion at all (out of round) from torquing the heads and you would be below minimum clearance for a forged piston. Step on it before the engine is completely warmed up and you will get what you have.

AMX69PHATTY

08-31-2006, 09:10 PM

I believe the .045 value is for Piston to Head clearance, not Piston Deck Clearance.
Standard AMC Head Gaskets, Like Fel-Pro Blue Perma-Torques, are .045 thick compressed.
So when the heads are torqued down, if the pistons come up flush with the Block Deck,
that is .000 Deck Clearance, then the gaskets provide the .045 Piston to Head Clearance.
So if your pistons are .045 down in the hole at TDC from the Block Deck you've got .090 Piston to Head.

There's a whole long post here somewhere that talks about quench.
What I got out of it was if the pistons get real close to the head, but .045 is the safe minimum,
then it creates a shock wave in the cylinder that promotes combustion and prevents detonation.
The .045 min. is to prevent a collision due to exspansion, stretch, or slop.

Do you have a copy of the Performance American Style Book ?
Did you ask the Engine Builder what his opinion was of .006 to .009 Piston to Bore clearance ?
Did fuzz401 mention what the Piston to Bore Clearance was in his 401 motor with Ross Pistons ?
Has he got the same Pistons as yours ?
Sorry so many questions, considering getting Forged Pistons myself.

Happy Labor Day Weekend :?:

1980_Cj7

09-01-2006, 03:40 AM

Fuzz has flat top pistons. Completely flat and flush on the top, no dish, with some big reliefs cut in for the valves. Ours have a .145 deep dish in the top. Fuzz's compression ration is 12 to 1 though and he has to run straight racing fuel and $11 per gallon. I'll ask him what his clearances are.

Fuzz's

http://img.photobucket.com/albums/v31/fuzzcj7/Picture015.jpg

Ours

https://home.comcast.net/~rwsr50/ComcastOnlineStorage/BadPiston_008.jpg

It does specifically say, IN UPPERCASE in the Ross instructions, that if a torque plate is not used, additional clearance above and beyond the .004 should be provided. It doesn't say how much additional though. All I know is, in addtion to all the time and work, we are now facing the expense of a new gasket set and a new set of expensive pistons, even if the machine shop cleans up the cylinders for nothing.

What I can't understand though is how the piston wear is right in the middle of the piston, top to bottom, when the bottoms are bigger than the tops. Why isn't the biggest part wearing first? How is the middle hitting and not the bottom? This will be easier to visualize when I post some pics later.

1980_Cj7

09-01-2006, 05:30 AM

82Waggy

09-01-2006, 06:14 AM

The bore would not be out of round with the heads removed, only when they are torqued down. This is the reason for using the plate, it distorts the cylinders while honing so that they will be round when the head is installed. .004 is the minimum wall clearance for a forged piston when everything is perfect.

That there is variation in the damage on each piston is no surprise as each cylinder will not necessarily distort the same amount from head torque or heat.

As a previous poster mentioned .045 is the typical target quench for an AMC and is obtained by establishing a zero piston to deck clearance and using an .045 thick head gasket. This usually requires a custom piston with the proper compression height (pin center to top). The required compression height is determined after rod resizing, block decking, and crank turning - or, if you use a piston that is close, maybe you can deck the block a few extra thousandths to obtain a zero piston to deck clearance.

If your piston to deck clearance is really .045 and you are using an .045 head gasket, the resulting .090 quench distance is too much and will result in uneven combustion. Make sure you are measuring from the deck surface to the high edge of the piston that encircles the dish. You are not getting the compression ratio you think with this combination of .090 distance and dish pistons - closer to 9:1.

fuzz401

09-01-2006, 06:57 AM

I think it was around .007 clearence
my pistons were made by ross for a AMC motor they are flat top
with 2 -6cc valve pockets
bore 4.165
stk 3.680
rod lg 5.858
bk hight 1.493
rings 5/64 - 5/64 - 3/13

they were ordered by the machine shop that did the motor the first time thinking of a 10:1 cr they did not look at the heads very good ended up with 12:1 cr instead
my deck height is 0
my head gaskets are the HP by ROL

but I will say watch your rod caps were the rod bolt nut sit's the new ARP nuts are bigger then the factory and the factory seat is not always flat thus the ARP nuts will only hit a very small surface on the rod cap

Goose

09-01-2006, 07:16 AM

Also the reason for the wear being in the middle of the piston and not at the largest point, is that is inline with the wrist pin.. which is where the forces are being transferred.(if you push on the top or bottom the place where it will or can flex or bend. so it makes sensethat it would thrust the middle of the skirt into the wall.. after all what was happening is the slug was sticking in the bore..(Might be you got off lucky.. It could have cracked a piston or really siezed in the bore and snapped a rod..).

You know I might catch some flack for this but here goes..I have always built engines on the loose side of tolerances (except bearing clearances).for one simple reason. they last. they are forgiving of abuse and while some out there are able to control the machining process to a few thou. When you are paying someone else to do the work, you dont always get what you specify. (OR in this case get someone to read the damn instructions cause I bet two more thou clearance and this wouldn't be an issue).

Good luck and Damn the bad luck!

Holeshot

09-01-2006, 07:46 AM

Ditto building engines on the loose side, especially the bores. I think .009" for my 4.195 engines is where I like it (for drag race & nitrous).

Nasty looking pistons!!!

Get yourself some Muriatic acid to eat the aluminum off the cylinder walls, THEN Sunnen hone them enough to get .009" clearance with the new forged pistons, or don't open up the bore & use KB hypereutectic pistons.

HotRod Mag Norm Brandes AMC builds...

http://www.hotrod.com/searchresults/?scope=t&sitename=hotrod&terms=norm+brandes&go.x=14&go.y=11

"Indy closed up the rear-chamber wall between the valves to yield superior quench. The KB piston (right, compared to the old Speed-Pro replacement forging, left) has a step that keeps the mixture out of the chamber's dead area, while the large flat dish area uses the whole chamber for a good burn. The result is a tumble-and-swirl-promoting 0.030-inch quench."
http://www.hotrod.com/techarticles/engine/113_0403_amc_12_ch_z.jpg

New KB AMC Pistons:
PN Engine CH Volume
KB354 401 1.51 inch -30.5cc dish
KB392 401 1.51 inch -17.3cc dish
KB394 390 1.56 inch -28.0cc dish

KB Performance Pistons/United Engine & Machine Co.
Carson City, NV
702/887-2971
800/560-4814
www.kb-silvolite.com

Here's another question for the builder, were these file-fit rings???
What clearance did he file them to???
Tight ring gap causes too much heat & the pistons grow too much, when the top ring grows enough to but, off comes the top of the piston!!!

1980_Cj7

09-01-2006, 08:43 AM

Also the reason for the wear being in the middle of the piston and not at the largest point, is that is inline with the wrist pin.. which is where the forces are being transferred.(if you push on the top or bottom the place where it will or can flex or bend. so it makes sensethat it would thrust the middle of the skirt into the wall.. after all what was happening is the slug was sticking in the bore..(Might be you got off lucky.. It could have cracked a piston or really siezed in the bore and snapped a rod..).

That makes sense.

And yes, no matter how bad your luck is, things can always be worse. I'm just happy it doesn't look like the block is lost. 401 blocks are a lot harder to come by than pistons.

Hmmmm, I just thought of something. Fuzz was driving our Jeep when the knocking started. Maybe we can sue him for a new engine. I hear he's loaded anyhow. :mrgreen:

Goose

09-01-2006, 09:21 AM

I heard he was loaded too.. but I don't think they were talking money...(anybody who drives a Short wheelbase jeep thats that fast.. has to have some fortification somehow :P) :shock:

1980_Cj7

09-01-2006, 10:14 AM

82Waggy

09-01-2006, 10:44 AM

Thus the reason that bores are usually finish honed and clearanced to match each piston to a corresponding bore.

I'd be holding your machinest accountable for too tight a bore clearance and maybe not even matching the bores to a corresponding piston.

Anyway, I think it is now clear what went wrong.

If you are going to spend the money on forged pistons again, clean up the bores, determine the diameter and compression height you need to establish a zero deck clearance - and the dish size necessary to establish about a 9.25:1 compression ratio, and then get a custom piston made by JE or Venolia to suit these dimensions.

And use a torque plate to finish hone.

PS: I used a custom JE forged piston for my 390 build that were matched made to fit the bores with the proper clearances and compression height. Used the KB 354 pistons for my 401 that we match honed and decked the block to fit - both zero decked + or - a thousandth or two - and then used an .045 head gasket.

AMX69PHATTY

09-01-2006, 12:53 PM

Here's a link to the Keith Black SilvoLite United Engine & Machine Co. Web site page that talks about quench.

it mentions something about .090 Piston to Head clearance being undesireable in thier opinion.

http://kb-silvolite.com/article.php?action=read&A_id=39

and here's a second KB SilvoLite web page that discusses Quench and Piston to Head Clearance

http://kb-silvolite.com/article.php?action=read&A_id=35

:idea:

and another about forces on the sides of pistons, neat graphics

http://www.kb-silvolite.com/feature.php?action=read&F_id=25
:-|

Blown7

09-01-2006, 04:45 PM

I heard he was loaded too.. but I don't think they were talking money...(anybody who drives a Short wheelbase jeep thats that fast.. has to have some fortification somehow :P) :shock:

Nah, no fortification, the hardest think he drinks is Turkey Hill ice tea. The reason he drives a short wheelbase jeep that fast is his rear view mirror. It says "Objects in mirror are dumber than they appear". 111!!!

I think things are finally starting to fall into place. I got to thinking, and pulled out the Ross inspection sheet. It gives laser measurements for each piston at the top, middle, and bottom of the skirt.

Cylinder #1, piston #D2, diameters from Ross inspection sheet: 4.1864 / 4.1902 / 4.1902 least damage

Cylinder #3, piston #A2, diameters from Ross inspection sheet: 4.1866 / 4.1904 / 4.1904 second worst damage

Cylinder #5, piston #B2, diameters from Ross inspection sheet: 4.1864 / 4.1902 / 4.1902 third worst damage

Cylinder #7, piston #F2, diameters from Ross inspection sheet: 4.1865 / 4.1903 / 4.1903 worst damage

The pattern being that the smaller pistons, which would have had more clearance, assuming the bores are all the same size, exhibited less damage.

One ten thousanth isn't going to make that much difference in the piston size, don't look for your answers there. You have to check the bore diameter verses the actual piston size. ( Don't even use the piston data sheet) A good machinist will use his own micrometer and verify the actual measurements. I run .008 thousanths on forged pistons and nitrous so far not a problem. You DEFINATELY have to let the engine warm up before you go anywhere with forged pistons. I run JE Pistons. I guess thats why I never saw that kind of damage, I do all my own work.
Also I did away with the offset piston pin hole in my custom pistons. another great useless idea compounded in the 1970's era engineering world.

Jeff

fuzz401

09-01-2006, 05:10 PM

I heard he was loaded too.. but I don't think they were talking money...(anybody who drives a Short wheelbase jeep thats that fast.. has to have some fortification somehow :P)

12.9 that's not that fast :? there cars with short wheel bases too ; they just don't see all the scenery like I do

Nah, no fortification, the hardest think he drinks is Turkey Hill ice tea. The reason he drives a short wheelbase jeep that fast is his rear view mirror. It says "Objects in mirror are dumber than they appear".

it is this that says it all
http://img.photobucket.com/albums/v11/fuzz401/Picture1.jpg

Goose

09-01-2006, 06:02 PM

Fuzz my friend.. I have gone 12.0 in a Gremlin and I'm willing to bet real money that, it's not nearly as exciting as that Jeep of yours at 12.9..
For one thing the windows were rolled up!

Also I like that decal.. I'll have to look for one of those!

fuzz401

09-02-2006, 12:59 AM

Fuzz my friend.. I have gone 12.0 in a Gremlin and I'm willing to bet real money that, it's not nearly as exciting as that Jeep of yours at 12.9..

that my next thing but 11 to 10 in a gremlin :?

12.9 in the jeep is not bad stright as an arrow no weave at all just like driving your car down the road :t:

1980_Cj7

09-02-2006, 04:41 AM

Fuzz my friend.. I have gone 12.0 in a Gremlin and I'm willing to bet real money that, it's not nearly as exciting as that Jeep of yours at 12.9..
For one thing the windows were rolled up!

And the worst part is, Fuzz does it with both hands tied...

to his steering wheel. He hasn't quite mastered "behind his back" yet.

1980_Cj7

09-02-2006, 04:47 AM

One ten thousanth isn't going to make that much difference in the piston size, don't look for your answers there. You have to check the bore diameter verses the actual piston size. ( Don't even use the piston data sheet) A good machinist will use his own micrometer and verify the actual measurements. I run .008 thousanths on forged pistons and nitrous so far not a problem. You DEFINATELY have to let the engine warm up before you go anywhere with forged pistons. I run JE Pistons. I guess thats why I never saw that kind of damage, I do all my own work.
Also I did away with the offset piston pin hole in my custom pistons. another great useless idea compounded in the 1970's era engineering world.

Jeff

I know actual measurements comparing each piston to the cylinder it is in would be best, but unfortunately I don't have the proper tools to do that. I'm thinking of finding someone (other than the guy who built the engine) who does, and have them measure and record what we have. [/quote]

1980_Cj7

09-05-2006, 09:16 AM

Anybody know anybody in the Harrisburg, PA area that would have a cylinder gauge and big micrometer to measure the pistons that would be willing to do some measuring for us?

AMX69PHATTY

09-05-2006, 01:01 PM

Maybe try a Tool Rental place for a 3-Point Bore Gauge ?
Ever heard of Enco ? www.use-enco.com 1-800-873-3626
They have a Dial Bore Gauge for $60 - #612-5920 <-- $40 on SALE !
and a 4" to 5" Outside Micrometer for $40 - #600-0025 <-- backordered
or a Set of Outside Mic's for 0" to 6" in a wooden case for $70 - #600-0006. <-- $61 on SALE !
They're not fancy schmancy but they'd work.
I shouldn't have looked, I might have to get a Bore Gauge myself for $40 ...
Bore Gauge
http://www.use-enco.com/CGI/INSRIT?PMAKA=612-5920
Mic Set
http://www.use-enco.com/CGI/INSRIT?PMAKA=600-0006

Holeshot

09-05-2006, 04:43 PM

If you want to get a quick idea of whatup, get a few feeler gauges (.002"~.009", long ones if possible) and your best piston & poke the piston & gauge into the best cylinder (should be no ridge yet), repeat with ever increasing gauge size until she-a-no-fit. As you already know, the piston is a little bigger towards the skirt.

At least you will know who needs the knots on his head sooner rather than later!!!!

1980_Cj7

09-06-2006, 08:11 AM

I was thinking about using the feeler gauges. I wondered if the width of them and the curvature of the cylinder and bore might cause a false reading though.

I just thought of another question though, at what point on the piston do you measure the clearance? The pistons are tapered .0038 top to bottom, so where you measure could make a big difference. Do you allow the specified clearance at the biggest point of the piston?

1980_Cj7

09-09-2006, 12:55 PM

Got the other head off and checked the deck height with the feeler gauge before pulling the pistons. The deck height is .020!

AMX69PHATTY

09-09-2006, 07:47 PM

Is what you're saying is the Deck Clearance is .020 ?
that top of the piston is .020 down in the hole when at Top Dead Center ?
That is called Deck Clearance.
Deck Hieght is the distance from the Crank Centerline to the block head surface.
On the 401 the stock Deck Hieght is 9.208".
This can be reduced by machining the block but is not normally done.
Just sharing information.
I've been told that on small block chev's that it's not uncommon to find
that the Block Deck is not truely square to the Crank Center Line
resulting in Deck Clearance differences in the bores from one end to the other
which yields slightly different compression ratios in each cylinder.
In that case they mill the block deck to equalize the deck clearance,
and this slightly reduces the stock deck hieght.
I have not heard that this "problem" exists with AMC V-8's since they're not that cheap chevy stuff :?:

To calculate deck clearance one takes
1/2 the crank stroke + Connecting Rod Center Distance + Piston Compression Hieght
and subtracts that from the block deck hieght.
Piston Compression distance is from the wrist pin centerline to the piston top.
In your case:
1.84 Stroke Throw + 5.858 Rod + 1.490 Piston Comp Distance = 9.188
9.208 - 9.188 = .020 Deck Clearance
Stock 401 Piston have a 1.508 Comp Distance, so say 1.510
If your pistons have the stock 1.510 Comp Distance then they would stick OUT of the Block .020 !
Are you saying they stick out of the block .020 ??????
Man, if that's the case, a head gasket is .045 thick, so the pistons are only .025 from the Head !
They say the minimum suggested piston to head clearance is .045 to .040 !

hmmmmm :-|

82Waggy

09-12-2006, 06:36 AM

I'm using KB354 pistons with a compression height of 1.51. These would have yielded a zero deck clearance had the block not required milling from stock.

My 401 block required milling .007 off the deck to square it up, which would have left the KB pistons sticking out about .007 but I lost a few thousands of rod length and crank stroke to reconditioning so my pistons only stick out of the bore about .002- .003 , yielding a quench height of approximately .042 - .043 with an .045 head gasket - which is right in there.

Stock 401 spec'd a piston to deck clearance of .002 (down in the hole), but this would have varied several thousandths from bore to bore on my out of square stock block.

The Speed Pro & TRW pistons are .005 shorter than the KB.

Not sure how you would get .020 piston to deck clearance with any of these pistons.

For reference, stock 401 deck height is 9.208, rod is 5.858, stroke is 3.68, piston ch is 1.508. After machining mine came out at 9.201, 5.855, 3.66, 1.51, give or take a thousandth here or there.

1980_Cj7

09-12-2006, 06:43 AM

I called it the wrong thing. What I am saying is the pistons are down in the holes .020 at TDC. I thought that dimension was supposed to be "0". I mic'd the head gasket and it is .045. We have Ross Racing forged pistons that are supposed to give 9.8 to 1 with 58cc heads. I don't have the piston spec/inspection sheet in front of me, but I'll check the compression height later.

Update: on the passenger side, only number 8 piston is scuffed, and not nearly as bad as the ones on the driver's side. And, it is scuffed on the opposite side from them, the lower side (exhaust manifold side) of the piston. It is about like number 5 in the pics above, but again, on the opposite side of the piston.

We had a second independent machine shop do some measurements, and they are also saying the clearances look OK. They also said the blackness on the tops of the pistons was normal.

Heard back from Ross, and they don't know what caused this. We are really stumped here. No way we are buying more pistons and putting this back together not knowing what caused it and correcting it. Ross mentioned maybe it could be cylinder wash from running too rich. They said that should show up on the lower side (exhaust manifold side) of the cylinders though. Our tail pipe is all black inside but our plugs look good. Fuzz saw them first hand and agreed. I can post a picture of the plugs later. We were running an Edelbrock Performer 750 carb set up at the baseline settings.

I keep going back to the timing issue and how the engine didn't want to turn over until we got the base timing to around 20 degrees and wondering if that plays into any of this. Guess we'll have to pull the timing cover and see if we can see anything awry with the timing set.

Any ideas?

Goose

09-12-2006, 10:25 AM

Well Since you added the part about the #8 scuffing on the bottom, I am even more inclined to believe you have some sort of clearance/cold sieze or maybe offset pins in reversedgoing on.. This is going to sound redundant but if you visualize the direction the engin assembly rotates you will see that with offset piston pins..(If they were reversed) you would be thrusting (stop snickering pat) against the top of the cyl wall on one bank and the bottom on the other bank.. (I would try to explain it butin trying to visualize it my brain locked up and refuses to reboot.) ..at any rate Im betting it is a mechanical issue and not timing/mixture related. You would need something way way out of wack.

1980_Cj7

09-12-2006, 11:22 AM

1980_Cj7

09-12-2006, 02:10 PM

Just checked the compression height on the Ross forged pistons. It is 1.493, so, the .020 down the hole that I measured with the feeler gauge checks out. Calculating it mathmatically, I get .017.

1980_Cj7

09-12-2006, 04:13 PM

These pistons DO have offset pins. It seems like they could only be installed one way, due to the eyebrow cuts for the valves, but I'll have to study them again and see if I can figure anything out. I don't know if there are right hand and left hand ones. I don't recall seeing anything in the instructions about having to install them a certain way, but I'm sure going to be looking close at all that tonite. I'd love to find out that they were installed wrong and that is what caused this. Not knowing why this happened is the worst part of it.

Should the pins be offset to the same side on both banks, or should they be different due to the different forces due to the rotation of the crank?

The pistons are engraved "A" thru "H". They didn't seem to be installed in any particular order though.

Well, after looking closely at the pistons and doing some crude measuring, it didn't appear that the pins are offset. The only reason I said they were earlier is that the guy who built the engine said they were. To be sure, I just called Ross and gave the technician our job card number and asked if these pistons had offset pins. He said they DID NOT.

Next I asked him if it mattered where they were installed other than the valve cuts being on the top (eyebrow orientation as opposed to smile orientation). He said NO.

Curses. I was hoping we were on to something there. Back to the starting line!

Anyhow, here's a pic of the plug that was in cylinder number 7, the one with the worst damage. All the other plugs look the same.

https://home.comcast.net/~rwsr50/ComcastOnlineStorage/PlugNo7.jpg

Goose

09-13-2006, 10:01 AM

Darn and here I thought I was becoming a theoretical genius..

That plug looks fine to me.

1980_Cj7

09-13-2006, 12:49 PM

Darn and here I thought I was becoming a theoretical genius..

And we were sure hoping you were!

If we were to look for a lubrication problem as the cause of this, where would we start?

We already verified that the oil holes on the rod caps were in the correct orientation. Oil pump and timing cover are new. Oil pressure was great. Lifter valley mod was done. Block was tanked.

Mudrat

09-13-2006, 06:46 PM

This is going to sound redundant ... You would need something way way out of wack. .. stop snickering pat
Guess adding anything to this wouldn't matter then :? :mrgreen: But I did like the offset pin pushing bit =D>

Goose

09-13-2006, 09:25 PM

YEA it sure sounded erudite and edjamacated didnt it??

Goose

09-13-2006, 09:35 PM

Ya know I was just looking at pyagids animated dojigger there and darn it was easier to visualize what I was talking about.
I don't know where you would look for oiling issues if the squirt holes were lined up and the bearing inserts werent backwards blocking them..unless for some reason you werent getting enough pressure through the crank..then you would think it would have spun a bearing..
Have you thought of finding a Priest and 5 quarts of holy water ?

Blown7

09-14-2006, 03:45 AM

Naw, look at these links
http://www.hastingsmanufacturing.com/Service%20Tips/piston_cylinder_scuffing.htm

http://www.aa1car.com/library/2003/eb40354.htm
http://parts.evinrude.com/OIL%20WEBSITE/carbon.html

I think your problem was a little of everything, not the squirter holes. My Carillo rods don't even have them.
First you had a terrible time of timing, bore size too tight. I don't know how long you spent on engine warmup.
Rehone that block to .006 thousanths clearance, call JE pistons get some good pistons in there. Check the ring clearances. Time the cam correctly.
Then you'll be good to go.

Jeff

1980_Cj7

09-14-2006, 04:52 AM

Thanks Blown7. I have already seen 2 of those links you posted. Guess I HAVE been doing my homework. That first one about the burr at the bottom is interesting. I'm going to check that.

As far as new pistons, what has any of you guys experience been with compression ratios? We want to be able to run pump gas. What would be the highest ratio we can go that will work? Don't care if we have to run 94 octane.

We have a deck height problem with the Ross pistons having a shorter compression height. Are any of the other pistons, JE, KB, etc. closer to stock in that dimension? (I'm going to check their specs myself, but I just wondered if any of you had any good or bad experiences with any of them.)

82Waggy

09-14-2006, 06:05 AM

The KB 354 has a compression height of 1.510, which would make up the .017 difference you have to obtain a zero deck clearance, and they are available in .030-.060 overbore - BUT, these are typically run tighter than a forged piston as they do not expand as much, so you may need to re-bore/hone your block to fit them properly. They have a 28cc dish and will yield somewhere around 9.7:1cr depending on your final bore dimensions. 9.7:1 may be a bit high but is dependant upon your cams intake closing point (dynamic compression ratio). Since you have the heads off, you might consider polishing the chambers to open them up a bit to around 62-65cc and reduce compression ratio to about 9.25:1. KB's site has several calculators you may find useful. These pistons can be ordered from summit at around 403.00. One additional cost downside is that they use smaller wrist pins so you will have to bush your rods. I'm using these in my 401.

If you do not rebore, probably your only alternative is to determine your final bore diameter after clean up and get a custom forged piston made to fit your circumstances - JE or Venolia can make exactly what you need to exacting tolerances so that you can fit the piston with proper wall clearance, pin diameter, dish size, and compression height. Custom pistons typically cost around 800.00 plus. I went this route with stock diameter pressed pins in my 390.

Whatever way you go, take this opportunity to hone your block with a torque plate.

82Waggy

09-14-2006, 06:20 AM

To clarify my previous post on custom pistons, you would have these made to the diameter you need to fit your finished bore with the proper wall clearance - so you would want to have your block finish honed first (all bores the same diameter) and get pistons made to match.

Holeshot

09-14-2006, 07:17 AM

You are using some sort of spark box, like MSD, correct? Makes reading the plugs harder. I'd say that the engine was extremely rich & the gas could have been washing the oil off of the walls. That, coupled with tight clearances & everything being new & not having polished itself to a broken-in condition, could be contributors. Never did hear whether the rings were file-fit & what the ring gaps were set at, but It seems that the "builder" missed the boat on the piston clearance, & setting the ring gap is a tedious & time consuming task that he may have skipped (?). Ask him what ring gap clearances he used & what he used to file the rings.

If we were to look for a lubrication problem as the cause of this, where would we start?

How about the engine builder's fee & whatever he used whilst you were grabbing 'yer ankles :oops:

That's totally a joke and I'm sorry, I just couldn't resist. :razz:

1980_Cj7

09-14-2006, 07:31 AM

No, we are not using a spark box. We are using the stock ignition with the exception of a Ford TFI coil.

Wouldn't the plugs be all carboned up if it was running rich enuff to wash down the cylinders?

We will check with the builder about the ring gap. I did look at the ends of the rings to see if they were shiney from rubbing together due to insufficient gap. They were not.

I have several books, "BJ Builds an AMC", "American Performance", etc. BJ didn't use a torque plate on the engine he built in the book. The builder we had check out our dimensions said he never uses one on any engines he builds. Don't get me wrong, I'm not saying it isn't better to use one, I'm just wondering how hard it's going to be to find a builder around here who has a torque plate for AMC's.

Also, is there any way to check the cam degreeing with the heads off and the pistons out?

Blown7

09-14-2006, 06:18 PM

Also, is there any way to check the cam degreeing with the heads off and the pistons out?

Not really, just throw number 1 piston back in. You need to find Top Dead center on the number one piston to determine where TDC is, to set the degree wheel. The heads can be off . You use the intake lifter from number 1 cylinder. You probably don't even need the rings on the piston to get close enough.

Jeff

1980_Cj7

09-15-2006, 05:39 AM

I know the cam will need to come out to rehone the cylinders, and be set up all over again, but I'd just like to know if it was set up right the first time before we tear it apart.

1980_Cj7

09-16-2006, 06:57 AM

Still wondering what happened to our engine. Was looking at the rod bearings and oil squirter holes in the rods. How does the oil get to the holes? There are no holes or grooves or anything in our Clevite bearings. Came across this post while researching http://www.bulltear.com/forums/viewtopic.php?t=3215

AMX69PHATTY

09-16-2006, 07:45 AM

82Waggy

09-16-2006, 08:27 AM

You need .005 - .006 minimum piston to wall clearance with forged pistons. You need to finish hone with a torque plate. With forged pistons you need to let the engine warm up fully before stepping on it.

My machinest laughed when I showed him the page in BJ's book that said he did not use a torque plate - GET ONE! - and promptly discounted the rest of BJ's book after that, as did I.

BHJ sells torque plates. http://www.bhjinc.com/1products/0-landing.htm

1980_Cj7

09-16-2006, 08:51 AM

On the ends opposite the locating tangs,
there should be half circle cutouts on the end of each rod bearing
where the two halves meet that makes a hole about 1/8" diameter
that allows oil to escape and feed the squirt holes.

That's what I thought! There are no holes, grooves, notches, or anything. The bearings are solid the whole way. I can't see any way any oil could have gotten to the squirter holes.

And we always let the engine warm up before going anywhere.

AMX69PHATTY

09-16-2006, 11:14 AM

82Waggy

09-16-2006, 11:58 AM

Lack of squirter holes may have been a contributing factor, but your p/w clearance of .004 is still too tight, especially for a bore that was not finish honed with a torque plate.

1980_Cj7

09-16-2006, 12:28 PM

AH HAH ! EUREKA ! Finally a "discovery" =D>

I don't know about Blown7 and the Carillo Rods with no oil squirt holes, but
would think the rod bearings lacking oil holes definitely contributed to the problem.
Why would AMC have put them in there if not needed ?
Sorry Blown7, I haven't built that many motors.
That's wild that your Carillo rods lack an oil squiter hole.
Maybe they're not all that neccissary, but I'd get rod bearings with holes.

:-|

I have been talking to a Keith Black technician, and he said the pattern of wear we experienced is caused by lubrication problems. Maybe we're finally on to something here. I am going to be talking to the folks at Maddog and Clevite about the bearings, and also to the people at Ross about why pistons for a 401 AMC engine did not have the proper compression height. I will also be asking the engine builder why he didn't catch both of these problems.

Holeshot

09-16-2006, 01:27 PM

I am going to be talking to the folks at Maddog

Well, right THERE is your problem!!!!!

They don't know SPIT about AMC engines, just selling parts!!!!

You probably got all uppers or lowers or seconds, something stupid like that.

Blown7

09-16-2006, 05:59 PM

Blown7

09-17-2006, 04:18 AM

Ok I have a few minutes this am to get into depth on why the squirter hole isn't necessary if the engine is done correctly. First here are some rods from another engine showing comparision to Carillo rods http://www.club4ag.com/faq%20and%20tech_pages/Connecting%20ROD.html
Next is a compulation of various ways a piston can scuff
http://www.acl.com.au/web/acl00056.nsf/a7d23b8ace0d7e31ca2560d3001fb663/a889f2115e9d9f944a2563c60024554e?OpenDocument

Primarily the squirter hole is to lube the wrist pin and very indirectly the cylinder wall. The function of the oil control ring is to scrape oil up to the compression rings for dynamic sealing.
The primary lubrication of the cylinder walls is by splash, the oil leaving the sides of rod bearings varies as the square or cube of the clearance, so a diff. of say .0005" could mean a big diff. in oil throw.

. Now we know the crankshaft is spinning throwing oil all around the bottom end of the engine and alot of oil is hitting the cylinder wall (if it wasn't that little squirter hole wouldn't be enough no matter how you sliced it. Especially considering it only squirts once every 360 degrees of connecting rod throw rotation.)
When the oil leaves the main bearing it courses up thru the drill hole to the connecting rod throw, lubricating the conn rod bearing,thenit leaves the bearing at the sides of the bearing between the rod side and the conn rod throw. Now this oil is flung constantly in a 360 degree radius all around the bottom end including the cylinder walls. The squirter hole is offset in the conn rod and when it aligns with the conn rod throw oil hole from the main it is pointed at the wrist pin not at the wall.
With this being said the what was the cause of your particular problem?
This is just my opinions.
First your piston to bore clearance was not enough.
Second What type of rings where installed? If you had high tension rings that would scrape excessive oil up to the compression rings thus not leaving behind enough oil to lube the piston.
Third where your connecting rods checked for straightness? and for enough clearance fron the big end to the crank throw (side clearance of the rod to the flange?) This allows enough oil bleedby.
Forth what and how was the inital cylinder lube applied before initial startup?
Fifth your initial timing was off considerably, very bad.
You had alot of things against you here on this buildup and to say that definatively one item was the downfall of this buildup is not true. I can't remember if you had full float pins or not but next time get them if the wrist pin froze in the piston it would also allow the piston to not float correctly in the bore and cause the problem also in conjunction with the squirter hole being blocked.
As one last thought my Carillo rods are thru drilled from the conn rod bearing to the full floating wrist pin. Best bang for the buck for keeping the wrist pin oiled.

Jeff

1980_Cj7

09-17-2006, 05:38 PM

Thanks for your thoughts and experience Jeff.

Rings are Hastings chromoly.

Pins are not floated, but all are free both side to side and rotationally. If you look at the first picture of the No. 7 piston I posted, it looks like the pin was getting plenty of oil.

Engine lube was whatever builder used for assembly. We added a container of assembly lube that I got at the Chevy dealer's to the Castrol 10W40 oil when we filled and primed the engine.

Don't know if the rods were checked for straightness or clearance. I will check.

Yes, I agree, the timing was screwy on this thing. I am going to check the cam timing before I tear it apart. Would checking the movement of the lifter work to check the cam, since the heads are off?

AMX69PHATTY

09-17-2006, 07:02 PM

Thanks Blown7 :oops:

1980_Cj7

09-19-2006, 04:56 AM

I asked Ross why the pistons we got didn't have the proper compression height for our engine. Here's the reply I got:

You are talking about a engine that is over 30 years old! Now if an engine builder gives me an exact block deck height I will zero deck the compression height if requested. I generally like .005-.010 down depending on side clearance because it will rock to zero. It is because of now knowing how much if any a block has been decked over the years that our standard deck clearance is .017. Now if I had zero decked the piston and your block was decked .015 and it stuck out of the hole would you have been happy? Most profession engine builders will get the pistons .010 down and square the block after.

Blown7

09-19-2006, 05:35 AM

I think now your understanding what building a "true high performance engine" means, the term "Blueprinting" is a misnomer it actually entails just checking every dimension against the manufacturers specifications and allowing the necessary tolerances to make the engine perform correctly. You cannot just buy a bunch of things and hope they fit, or expect the engine builder to know these things, it's up to you to do the homework. When you buy custom pistons you have to know the exact dimensions and deck height is one of them. Get the JE pistons custom order form and look at all the dimensions JE needs to build a piston FOR YOUR ENGINE.http://www.jepistons.com/pdf/custompistons-orderform.pdf

I think it's time to check the cam timimg before disassembly and yes just use the lifter on number 1 like this
http://i25.photobucket.com/albums/c96/Blown7/newpicjune10038.jpg

Also notice the o ringed block for higher compression, and I marked every piston for the ring gap location. STP and engine oil makes a great build lube. Forget the Hastings rings and go with Speed pro rings.
Jeff

Scott H

09-19-2006, 06:19 AM

RE: Get yourself some Muriatic acid to eat the aluminum off the cylinder walls, THEN Sunnen hone them enough to get .009" clearance with the new forged pistons, or don't open up the bore & use KB hypereutectic pistons.

If you use Sodium hydroxide (LYE, active ingredient of DRANO) it will disolve the aluminum without eating the cylinder bore. HCL (muriatic) will disolve the iron bore almost as agressively as it disolves aluminum. Note that both are dangerous to your skin and lung tissue so do it with proper ventilation and protective eyewear and rubber gloves.

Depending upon forging alloy used, 4032 alloy can be run snugger than 2618 alloy but IMO 0.004" is too tight. I would go with 0.007".

1980_Cj7

09-19-2006, 08:35 AM

Yep, we're learnin'. This is our first time at having an engine built. We didn't do it ourselves because we are smart enuff to know what we don't know. We took it to an engine builder because we thought they knew what we didn't.

The engine is nowhere near the level of performance stuff you're into Jeff. The only thing not stock is the pistons and cam. We just wanted to get a little more than stock performance out of it since we needed to rebuild it anyway.

So, would you guys who are more experienced at this stuff mind giving us some recommendations for this second time around?

The engine will be in a CJ7 used for serious rock crawling and also driven on the street. We'd like to get as much power out of it as possible of course, but want it to run on pump gas. Having to use 94 octane is no problem.

So, what would you recommend as far as pistons? Cast, hypereutectic, forged? (I understand the part about knowing the bore and deck dimensions before ordering.)

What kind of clearance for whatever pistons you recommend? (I know it varies depending on the type of piston.)

How about compression ratio to work with the pump gas?

How about intake and carb? (We know fuel injection is the best, but the budget definitely won't allow that at this time, especially after having to do this twice in 300 miles.) We had an Edelbrock Performer intake and Performer 750 carb on it, but have access to an Air Gap too.

Anything else we're forgetting?

Oh yeah, to save you digging back thru the posts, the cam is a Clevite 284 hydraulic (218/218@.050, .488/.488 lift, 105/115 separation).

Thanks for the help.

Holeshot

09-19-2006, 10:40 AM

(muriatic) will disolve the iron bore almost as agressively as it disolves aluminum

In 25++ years of being a certified Honda & Suzuki mechanic & using muriatic acid to remove aluminum from cylinder walls, as directed by the Honda, Suzuki, & Yamaha factory service directives, I have NEVER had a bit of a problem, nor heard of any BS about muriatic not being the solution for that particular problem. We have ALWAYS had a jug of muriatic in EVERY shop I EVER worked in, and that is quite a few, from Alaska to Texas, Michigan & Indiana.

On another note, I went back through some of my AMC power literature, outlining SuperStock & TransAm AMC engine builds, and most of the engines put together with forged pistons used between .007"~.009" wall clearance, including the little teeny overbored 290 (302).

Pistons- you should be able to get by w/o another bore job, get yourself some forged flattops & hone the cyls for .007"~.008" clearance, as recommended by the mfgr. The CR that you order should be determined by the CCs of your combustion chambers, I'd want to be ending up with at least 10~1 - 10.5~1, & be SURE to have the .045" PTHC.
Not suree what type of mods your heads have had, but "open-chambering" is a very worthy mod that should net your chamber size to the low 70s, as I recall. Which would be around 11~1 with 13.5~1 pistons, so you REALLY NEED to know what size your chambers are & what your deck clearance is before you can order pistons. Generally, you will need to order pistons rated for 12.5~1 (or so) with 50 or 51cc chambers to end up with 10~1 with the 70-something cc chambers, so you MUST do the math FIRST, then incease the valve cleearance cuts in the pistons or the volume of the combustion chamber to lower the CR to where you want it. If you get another set of pistons that have domes looking like the stockers or the siezed ones, you will most likely have a ping problem at ANY compression ratio, because there is no way to get .045" PTHC with those pistons, and you would probably be very lucky to get much over 8~1 with them anyway.

Do yourself a favor & get the rods bronze bushed & use full-floating & forced-oil oiling, wrist pins.

Rings - I will always pay the extra $100 for gapless rings, they leak 0% after break-in, compared to normal rings that will leak at least 2% when new & always be in a state of deterioration, leaking 8~10% in fairly short order. That is around a 10% loss of power, & also may let a little oil into the chamber where it can cause detonation & engine destruction.

82Waggy

09-19-2006, 01:36 PM

Just got back from my machine shop where I had occasion to discuss your problem.

1) Regarding Ross pistons, my guy said they use a couple of different alloys and that in some cases they punch the bores out as much as .010 - .012 P/W clearance. Also said that even with the higher quality Ross pistons they never run them as tight as .004 and usually well over .006.

2) While I was there I double checked my own two sets of rods for the squirt holes and they were all still present after resizing. When asked why I was worried about it I explained your situation and was told that the engine should still live just fine without it if P/W clearances are correct.

In summary, he felt that .004 was way too tight, flat wrong for a non-torque plate honed bore, and that you may have also had some dirt to compound the problem.

They build 1200hp nitrous engines regularly, as well as some real old oddball stuff - like a 52 cadillac, etc..

So there's another opinion for what it's worth.

1980_Cj7

09-19-2006, 03:48 PM

We just dropped the engine off at another machine shop. They measured while we were there and said we have .003 to .004 clearance! Even worse than we thought. They used a 3 point bore gauge and that seemed to be giving much more accurate measurements than the 2 points that the other guys both used.

They said that if it was a clearance problem, it should be scuffing on both sides of the pistons though.

They were also concerned about the way the rod bearings looked after only 300 miles. They said they wondered if the rods were reconditioned. I wasn't sure. We left it there for them to check out. Should know more tomorrow.

Blown7

09-19-2006, 04:10 PM

IMHO keep the engine with cast pistons with a 8.5 to 1 compression
at the bore that you have now, run the gapless rings, mod the connecting rods with a oil hole at the top for the wrist pin and file the conn rod bearings for the squirter hole. Polish the crank again. Install a less radical cam. Basically just try to get a little higher performance engine with out the hassle of Forged pistons, you don't need them, a fresh ,good running 401 will give you all you need. Stick with the basics for now. Do you want to give Fuzz a run? Just make a good running dependable engine. You have spent alot of cash already for nothing, and you'll still spend more .

Jeff

1980_Cj7

09-20-2006, 05:10 AM

Compete with Fuzz? No way, he got way more...

money than we do, ha, ha. We can't afford that kind of HP.

Actually, we weren't impressed with the power this engine had in the short time it was running, but maybe that's because of all the problems it had too. Wish I knew someone with a more or less stock 401 we could take a ride with to see how it runs. Fuzz actually gave us each a turn driving his, back when we were trying to decide whether we wanted to get a 401, but he definitely doesn't fall into the "more or less stock" class.

Hmmm, maybe this whole fiasco is his fault for getting us all excited about a 401??? There's those lawsuit ideas popping into my head again.

Blown7

09-20-2006, 05:35 AM

Trust me, having owned brand new full size Wagoneers back in 1976 with new 401's I drove back and forth to work in Hartford everyday on I-84 with the speedometer buried way past 100 MPH everynite. A good running stock 401 in a FSJ could easily keep up with most musclecars
with a few execptions) either in acceleration or top speed given the then state of the art technology. I never quarter miled one for time slips but just as the old road rules applied I can remember getting the Waggy near 80-90 in the quarter in a 4500 lb plus truck ,in a CJ it'll make you wet your pants. Just do a good mild build with quality workmanship you won't be disappointed.

Jeff

Goose

09-20-2006, 08:04 AM

I would be willing to bet.. that with a stock bottom end, you could make very close to 400 horse from a 401 from the deck up.. cam/heads/intake Carb.ignition . exhaust and tuning. (Ok if youre gonna spin it 7500 rpm it'd be scrap pretty quick.. but reasonable rpm 6500 or so , no sweat) but for the most part.. 300 real world hp is a lot 400 is gobs.. (not bragging dyno hp real HP 250 hp to the ground at the rear wheels is a bunch ) all of the muscle cars were 300 to 425 hp..426 hemi? 425 hp..

Yeah I know another vote for sensibility.. not pretty , cool or glamorous.. but it will still be running when the trailer queens are broke/wore out.

(just by way of explanation after grenading a 5000 dollar 401 in a Gremlin learning the difference between optimum quench and rod stretch at temprature/rpm.. on the first full pass..I learned.) :oops:

Holeshot

09-20-2006, 09:08 AM

Regarding the squirt holes in the rods, THE 1971 AMC technical service manual states, on page 2-10:
The connecting rods are stamped with the cylinder numbers in which they are assembled. The numbers are opposite the squirt holes and face the outside of the cylinder in which they are located. The connecting rod squirt holes in one bank lubricate the cylinders in the opposite bank

I do believe that the designers of the AM V8 had a bit more knowledge than anybody here, and they got it right, with the exception of the oiling issue solved by the bypass line.

Goose: did that $5k 401 you trashed happen to have aluminum rods or have forced induction? Those two apps must necessarily have more PTHC, failing to provide the added clearance will allow the pistons to strike the heads. Normally aspirated with steel or iron rods were to use .045" (.040" abs min) as optimum, as you know, I'm sure. If someone did not check EVERY cylinder, flaws in the blueprinting could enable damage to occur.

1980_Cj7

09-20-2006, 11:30 AM

The heads are stock with new valves, springs, etc. and a new valve job, so we want to stick with them. (Actually we WANT Indy aluminum heads so maybe I should rephrase that to so we have to $tick with them, money-wise.)

We have had the cam we picked called "radical", and also "not much more than stock", so I don't know what to think. Again, Clevite 284, 218/218 @ .050, .488/.488 lift, 105/115 separation. The way I compared it, it should have a little more duration and a little higher lift than stock. It idled fine, just enuff lope to sound nice.

We have both Edelbrock Performer and Air Gap intakes available.

We are working on an HEI/TFI ignition mod. Just a few bugs to resolve.

Exhaust is stock cast iron manifolds, the streamlined better-flowing header-looking ones, not the "logs".

So, that leave the biggest decision the pistons, as the compression ratio will be a direct result of which ones are picked. Again, must run on pump gas with no octane boosters or anything.

This engine will see more time at idle and just off idle crawling big rocks than anything, but we'd still like to be able to spin the tires and set ourselves back in the seat on the street for short blasts once in a while. It will probably never see much over 5000 to 5500 RPMs.

AMX69PHATTY

09-20-2006, 12:11 PM

82Waggy

09-20-2006, 12:46 PM

I do believe that the designers of the AM V8 had a bit more knowledge than anybody here, and they got it right, with the exception of the oiling issue solved by the bypass line.

Bypass line is worthless, does nothing, can flow no additional oil unless gallery is blocked since pressure is otherwise the same at both ends - it is a closed loop back upon itself.

Only way to increase oiling to the mains is to increase system pressure or decrese pumping to the top of the engine with reduced ID pushrods.

jeepsr4ever

09-20-2006, 01:27 PM

Actually the oiling line does something but its not at the end of the cycle its the begining. By forcing more oil to the back of the block it improves the flowback due to the mains being fed well and that where its primary benefit lies.

I would say the bore on this motor was wrong and it should be checked again.

1980_Cj7

09-20-2006, 02:56 PM

Not that I'm an expert, but the way I understand it is
that forged pistons are for high rpm reliability, like more than 6500.
I think Perormance American Style says cast pistons are ok for up to that much.
So for the rpm's yu're looking for cast pistons should be ok.
But, cast pistons come with what ever dish volume they are,
whereas forged pistons can be ordered however you want them.

So lets see, you have a 401 .030 over with stock 58cc Heads right ?

9.208 Deck Ht., 3.68 Stoke, 5.858 Rod, alll nominal
So if we make a target Deck Clearance of .005 in the hole,
you need a piston with a 1.505 Comp Hieght,
and to get 9.5:1 compression, you'd need a 28cc dish.

So if my numbers are right you need a 28cc 1.505 Comp Ht Piston to get 9.5:1 Compression.
I believe stock 401 Pistons are 1.508 Compression Hieght.
Trouble is most aftermarket replacement pistons are shorter as you've found out.

Please let me know if any of the specs are different for the parts you have.

I think the cam you have would be ok with 9.5:1.
did you keep the lifters in order as to what hole they came out of ?

Let me know what compression ration you're after and your specs
and I'll do what I can to help and run calculations to help select pistons.

We're after whatever compression ratio is going to give us the most power and run on pump gas, even if we have to go to 94 octane.

.030 over with stock 58cc heads, correct. All the dimensions on the engine are stock. The Ross pistons we had trouble with have .145 deep 23cc dishes and have 1.493 compression height which puts them down the hole .017. Ross claims a 9.8:1 compression ratio with them.

We were getting pinging on 94 octane if we advanced the timing to where the engine would produce any kind of power. When timed with a vacuum gauge, it wanted 20 degrees initial timing (advanced to get max vacuum of 17" backed off 2" to 15", then checked with the light). At 15 degrees initial we were getting 35 total. The engine would crank very hard until you got the timing to 20 degrees, then it would crank over normally. With initial timing down at 10 degrees, the engine was deader than a doornail. The tired old 258 would have run circles around it. As I have been saying though, something seemed srewy with the timing on this engine. I did verify that the timing marks were correct.

We only picked forged pistons because they were the only ones we could find in the 9.8 CR that we hoped would give us a little extra power, but still work on pump gas.

Blown7

09-20-2006, 05:55 PM

Regarding the squirt holes in the rods, THE 1971 AMC technical service manual states, on page 2-10: [quote]The connecting rods are stamped with the cylinder numbers in which they are assembled. The numbers are opposite the squirt holes and face the outside of the cylinder in which they are located. The connecting rod squirt holes in one bank lubricate the cylinders in the opposite bank

I knew that, I've got the same manual I purchased new in 1976!
Doesn't mean the engineers knew it all, you got to remember that engines were produced on a assembly line where time to fit all the parts correctly, and to basic tolerances was not a issue, time is the enemy on the assembly line. Squirter holes are a bandaid fix, we even have them on aircraft engines and Rambler had them back in the 1950's.

As for the pistons when you get to a corrected compression ratio of around 12.4 to 1 pump gas becomes a no go.
Corrected Compression Ratio = FCR - [ (altitude??1000) x 0.2 ] at 59 degrees F 29.92 inches of Mercury and don't forget your cam and it's timing will also play a part in your final compression ratio.

Jeff

Blown7

09-20-2006, 06:16 PM

AMX69PHATTY

09-20-2006, 06:39 PM

Here is the compression ratio that an excel spreadsheet I made
comes up with using the provided numbers.
It comes out with the compression Ross claimed.

http://mywebpage.netscape.com/SketchKT/AMC+401+Ross+Pistons+CR.jpg

And here's what it comes up with for the Keith Black 354 Pistons
Shortened the Connecting Rod by .003 due to re-conditioning in these calculations
http://mywebpage.netscape.com/SketchKT/AMC+401+KB354+Pistons+CR.jpg

I'm not sure what was going on with the timing.
About 35 degrees total should be about right and
9.8:1 with 94 octane gas should work good without pinging.
I would stick with a dial back timimg light rather than the vacuum gage method.
The cam can reduce the engine vacuum at idle due to overlap.
Make sure the Distributor is properly phased, curved, and installed.

Sounds like to me you had everything picked out and set up right.
There seems to be agreement the Pistons were to tight in the bores.
Deck Clearance of 0.000 is optimum, but .017 in the hole should be ok.
There seems to be disagreement about the oil squirter holes.
Does anyone have old stock Rod Bearings in the size you need with holes ?
Can you put the crank, #1 Piston/Rod, Dampener, and Timing cover
back on the block and check the timing marks using a dial indicator
to indicate Top Dead Center on the piston and see if the marks line up ?

Has Ross agreed to replace the pistons ?
Or have you decided on replacement Pistons ?
If you're not going to be driving in the winter the AirGap would be good,
but due to larger runners it shifts the torque curve up some in the rpm range.
Make sure and use a fuel pressure regulator set to 5-1/2 psi.
Low engine vacuum makes a carb run rich, this can be fixed with springs or power valves.
Said you had an Edelbrock right ? May I ask the part number ?
Manual choke style is set up richer than the electric choke model.

So does everyone else agree that everything seemed to be set right ?
Other than the pistons being to tight and the timing wierdness ?
Reading through the posts it seems that way.

Man, 1980_CJ7, I hope you get it back together and it works out right.

Blown7

09-20-2006, 07:24 PM

Speaking of the heads where they ever CC'd? To find out the actual chamber volume? And from the pics of the block it looks like it was decked (too shiny)

https://home.comcast.net/~rwsr50/ComcastOnlineStorage/BadPiston_009.jpg
So that chart you have, may have errors made on assumptions.

Jeff

FuzzFace2

09-20-2006, 07:47 PM

On the timing try another light as some ign. systems don‚Äôt play nice with some lights I‚Äôm told. You are running an HEI right every light should work with it???

I had a 304 that when checked with my light (snapon dial back) came up with 40* BTDC no vacuum. I checked the timing marks to make sure they where true and they where. The dist. was an old Mallory duel point with a mag. Pick up conversion, no box & steel core wires.
Thinking RF noise from the wires to the pick up and maybe the light I updated the ign system to MSD ( dist., 6al box, blaster coil, 8.5 wires) setup. Well even with the MSD setup light still did the same thing funny thing is light worked on my stock 75 v8 Gremlin!
Never did find out why it came up with 40* BTDC as motor got a knock so I built a 360 can‚Äôt remember if I put the light to it yet but motor starts faster & sound like it runs better.

Note to self: put timing light to 360 motor!
Dave ----

1980_Cj7

09-21-2006, 05:43 AM

Let me try to answer everybody's questions.

Didn't use a dial indicator, just did it by feel, but I did bring No. 1 piston up to TDC with the head off, then checked the timing mark, and it was right on. I'm pretty comfortable that I had TDC even without a dial indicator because I went back and forth a couple times, then when I checked deck clearance with a feeler gauge, I got .020. Calculating mathmatically gives .017, so I'd say I was very close.

We have a Craftsman adjustable timing light. Ignition is stock with the exception of a Ford TFI coil. Good point on trying a different timing light. Never thought of that. That's what's great about these forums, two heads are better than one. Come to think of it, we did try a different timing light, well, kind of. Fuzz checked the timing at his place, but...he had the exact same model timing light we do.

The Edelbrock Performer 750 CFM carb was an electric choke, I forget the model number, but the whole choke assembly was removed and the holes where the shaft went thru were plugged with epoxy. We set it up for the base setting on the manual chart.

Not sure it the block was decked or not without checking the machine shop bill. It would seem it wasn't because the deck clearance measured exactly what it calculates to mathmatically with the compression height of the Ross pistons.

The heads were not cc'd.

I still want to degree the cam when we get it back from this latest machine shop that is looking at it.

Jeff, how do we figure the cam and it's timing's affect on the CR?

Goose

09-21-2006, 06:09 AM

Yep.. aluminum rods.. Looking back I think jeez what a Dumb@ss.. but then just like in this thread, It's not the first 999 little details you check and double check.. it's the one that doesn't even occur to you ..

(But with out those occurances we wouldn't have any cool stories would we?)

John Strenk

09-21-2006, 10:35 AM

Here's the pics as promised. The first pic is No. 1 on the left and No. 3 on the right. The second pic is No. 5 on the left and No. 7 on the right. All showing the top (intake side) of the pistons.

https://home.comcast.net/~rwsr50/ComcastOnlineStorage/BadPiston_012.jpg

https://home.comcast.net/~rwsr50/ComcastOnlineStorage/BadPiston_013.jpg[/img]

Just a silly question, Did you have this block line (or "Align") bored or honed? What if the crank was off a little bit front to back. ? If this block has never been touched since it was first manufactured things could of "shifted" a bit.

Also George I alway use a torque plate with those clearances but I'm not a big block builder. It's been years since I even owned a V8. :)

jeepsr4ever

09-21-2006, 12:23 PM

Looks to me like the bores arent correct our you overheated the engine quite a bit.

1980_Cj7

09-21-2006, 01:07 PM

Oops, missed a couple questions above. Ross hasn't offered to do anything for us. Nor would I expect them to if it wasn't their fault. We haven't really pinned down what caused this yet.

Haven't decided on replacement pistons yet. The way I understand it, forged are more touchy than cast or hyper, like having to be warmed up for one thing. Thinking about the Keith Black 354's hypers that give the 9.5 CR, if I can be assured they will run on pump gas. I like the support KB has been giving us, even though we didn't buy their pistons, and all the great tech they have on their site. Their pistons have the proper 1.51 compression height to give the 0 deck clearance too. Need to see how the bores clean up first and decide what to do from there.

MC, the engine wasn't over heated. Highest it ever saw was 225 maybe. We put a new oil filled mechanical Autometer temperature gauge in before we ever fired it up so we could keep a close eye on the temp. Put an Autometer oil pressure gauge in too. Those stock CJ gauges leave a lot to be desired.

John, don't know how the engine was bored, other than the fact that a honing plate was not used. I asked about that after we had this problem. It was still stock when we got it, and not being engine builders, but at least knowing what we didn't know, we took it to a builder and just told him to do what needed done. We did have it balanced.

I did notice when checking for burrs at the bottom of the bores, like someone posted about, that there is a step in the bottom edge of the cylinder walls. Hard to describe. Wish I could draw a picture. The interior bore is straight and smooth, but as you turn the corner at the bottom of the bore, like to feel the thickness of the cylinder wall, there is a distinct step there. Does this make sense? Has anybody else experienced this and is it normal?

John Strenk

09-21-2006, 03:20 PM

I was talking about how the crank sits in the engine.

Read about align bore crankshaft:
http://www.eddiesvalvegrinding.com/boring-honing.htm

1980_Cj7

09-21-2006, 06:09 PM

I was talking about how the crank sits in the engine.

Read about align bore crankshaft:
http://www.eddiesvalvegrinding.com/boring-honing.htm

Yes, I understand. I just wanted to add something else I discovered to this thread in case it is pertinent.

AMX69PHATTY

09-22-2006, 03:39 PM

Nominal Compression calculations for the KB 354 Pistons.
Shortened the Connecting Rod by .003 to represent re-conditioning.

http://mywebpage.netscape.com/SketchKT/AMC+401+KB354+Pistons+CR.jpg

Here's the calculations using the stock Connecting Rod Length
http://mywebpage.netscape.com/SketchKT/AMC+401+KB354+Pistons+StkRod+CR.jpg

1980_Cj7

09-22-2006, 05:13 PM

Thanks. Now, is anybody running that kind of compression ratio on an engine similar to ours and will it run on pump gas without pinging?

Still waiting to hear back from the machine shop.

Blown7

09-23-2006, 02:37 AM

Jeff, how do we figure the cam and it's timing's affect on the CR?

First let me say I'm no cam expert, cam theory is even debated by the experts. Find yourself a expert and let them figure it out, but heres a elementary link to explain whats going on.
http://e30m3performance.com/myths/more_myths1/comp_ratio/comp_ratio2.htm

Then move into a more detailed explaination
http://www.empirenet.com/pkelley2/DynamicCR.html

And here is a calculator
http://www.kb-silvolite.com/calc.php?action=comp

Then you have to consider the cam timing to engine (with the timing wheel and the dial indicators) and where and what keyways you use on the cam timing gear to advance or retard the cam. The problem your going to get on a forum like this or anyother for that matter is your going to get a engine built by a commitee. You have to figure WHAT YOU WANT then what you want for performance, and then your going to have to compromise to get it. Whether you want low end grunt or high end power.

Unless you build a blower engine, then you can have it all :lo1l: BTW I can change dynamic compression ratio just by changing blower pulleys.

Jeff

1980_Cj7

09-23-2006, 07:50 AM

Thanks again Jeff. I ran the calculations with our numbers and here's what I got. I tried to cut and paste from the calculator, but it only pasted part of the numbers. Seems like it left out the numbers I filled in, and only pasted the calculated numbers. Anyhow, at least is shows the bottom line, the compression ratios. The static is very close to Ross's published 9.8. The dynamic with our cam came out to 9.2. Seems like that should have run on pump gas. I still suspect something is awry with the timing. Can't wait to get it back from the machine shop and check the cam timing. Fuzz has a degree wheel so we're gonna visit him and together see what we can find.

Again, our intent wasn't to build anything radical, but to just cheat a little more power out of the engine since we had to buy new pistons anyhow.

ENTER YOUR DATA CALCULATED DATA
Cylinder Head Volume (cc) Cylinder Head Vol
(cubic in.) 03.538
Piston Head Volume (cc) Piston Head Vol
(cubic in.) 01.403
Gasket Thickness (in.) Swept Volume
(cubic in.) 50.863
Gasket Bore (in.) T.D.C. Volume
(cubic in.) 05.820
Cylinder Bore Diameter (in.) Gasket Volume
(cubic in.) 00.644
Deck Clearance (in.)
Note: Neg. nubmer above deck, Pos. number below deck Deck Volume
(cubic in.) 00.235
Stroke (in.) STATIC COMPRESSION RATIO 09.739

OPTIONAL DATA
Rod Length (in.) Adjusted Stroke (in.) 03.456
Intake Closing Point (degrees)
ABDC @ 0.050 lift plus 15 degrees DYNAMIC EFFECTIVE COMPRESSION RATIO 09.207

Luv your blown engine! (Hey guys, I think we just found somebody with more power (read "money") than Fuzz. :mrgreen: )

AMX69PHATTY

09-23-2006, 08:48 AM

Here's the calculations using nominal values for an engine I had in my
'69 AMX for many years and I had no problems with pinging on pump gas.
It's out of the car now cause I spun a rod bearing taking it to ~7000 rpms
and it was not built for that and I didn't have the oil line in the lifter valley.

http://mywebpage.netscape.com/SketchKT/AMC+365+Cast+Pistons+CR.jpg

The hydraulic Cam was a stock unit reground by Chet Herbert.
Only have limited data on it, .512/.529 lift, 280/295 adveritsed, 110 centers.
Used Crane Hi-Intensity semi-anti-pumpup Lifters.
Cast Sealed Power Pistons, dished tops with 29cc, .020 shorter than stock.
Manufacturers of stock type replacement pistons make them .020 shorter
to allow for Cylinder Head and Block deck milling and to still maintain stock CR.
I have a '69 343 block with the shorter deck hieght, 9.175
Stock 343 4V had flat top pistons that were .060 down in the hole.
The Sealed Power units were .080 down in the hole with a huge dish.
This was "made up" by using a 304/360 crank in the 343 block.
There is a .160 stroke difference between a 343, 3.28, and a 304/360 crank, 3.44.
So the 304/360 crank pushed the pistons up .080 further to 0.000 deck and
with the dish in the SP Pistons compression came out at 9.5 thereabouts.
Recurved Distrubutor, 26 deg mechanical, 10 deg initial, 36 total at 3500.

I did not have any problems pinging running pump gas in this motor.
This motor made about 400 HP at the flywheel, 325 HP at the tires.
It chassis dyno'd 285 HP at tires before swapping on milled ported heads.
325 Tire HP calculated using the cars wieght and 1/4 mile MPH from the track.

I am currently working on getting this motor back together with more CR.
This time I offset ground the 304 crank .010 for a 3.46 stroke
and the pistons stick out of the block .007-.010, and CR is around 10:1.
I am also advancing the same cam 4 crank degrees where before it was strait up.
This closes the Intake valve sooner and creates more effective CR.

Per the SilvoLite page compression calculator.
I'm surprised my Dynamic compression was less than 8.0:1
That goes along with me not having detonation problems, like 82Waggy mentions below.
http://mywebpage.netscape.com/SketchKT/AMC+AMX+365+Nom+KB+Compressions.jpg

82Waggy

09-23-2006, 09:32 AM

Dynamic compression ratios in excess of 8:1 are typically considered too high to run on pump gas, and you generally want less if you are going to be towing or lugging the engine to prevent detonation.

If you are planning on using the KB 354 28cc dish pistons, just do the math and try to get as close to zero deck as you can within a couple out or three - five thousandths down (after decking the block square, taking off as little as possible) . With an .045 thick head gasket (4.275bore) you will have a good quench distance (.043 - .050 is good for a steel rod 401).

You then should probably consider polishing out the head chambers to around 62- 65cc to get the static compression ration down as close to 9 - 9.25:1 as you can - polishing the chambers (smooth surfaces) also helps reduce potential detonation.

With proper bore clearance you should be golden.

Oh, and go ahead a put that valley line in. So long as it does not leak it won't actually hurt anything. #-o

AMX69PHATTY

09-24-2006, 01:52 AM

I added an image of the SilvoLite page calculations for my 365 engine to my previous post.
My dynamic compression was less than 8.0:1
so that goes along with what 82Waggy had to say about detonation.

Here is the specs I fould for what I believe is your Clevite Cam
and the results of the SilvoLite Compression Calculator for your 401.
It indicates a dynamic compression of 8.63:1.
I wonder if this much dynamic compression may have been causing detonation.
Wonder if detonation may have something to do with the piston scuffing ??
Let me know if any of the values are incorrect.
This is interesting since I'm currently building an engine myself.

http://mywebpage.netscape.com/SketchKT/AMC+401+Ross+Pistons+Clevite+Cam+Info.jpg

http://mywebpage.netscape.com/SketchKT/AMC+401+Ross+SilvoLite+Comp+Ratios.jpg

Blown7

09-24-2006, 04:48 AM

Awww AMX69PHATTY your doin all his homework for him, I was hoping 1980CJ7 would figure this out all on his own. Yes the numbers sound about right, a recipe for a internal engine nuclear bomb. Unless you run high octane fuel or alcohol.

Typically the cams with over 112 degrees are some pretty finiky cams.
This is the reason why a engine is absolutely built around a cam as the FIRST item. Pistons being one of the last as the pistons can be massaged to work.
Thats why I like these new tuner kids you hang with them a while and find they are running damn near 20 to 1 static compression pistons in those little Hondas and yet running pump gas.

Jeff

82Waggy

09-24-2006, 05:50 AM

I went with a Crower grind myself, with an intake closing point closer to 60 ABDC.

You have to watch cam selection as many are designed to improve dynamic compression ration on low static CR stock engines.

The following static CR recommendations were clipped from an article on the KB Site. Note that these are for "regular" grade gas. You might get away with another .25 or so in CR if running Premium gas.

-----

The following compression guide should be considered realistic for sea level operation. Cam timing and special applications can move the recommendations around some, but in most cases the following recommendations work.

PUMP GAS (regular)
8.5:1-Non-quench 2 valve head road use standard sedan, without knock sensor.

8.5:1- Quench head engine for tow service, motor home and truck with torque cam.

9.0:1- Street engine with proper .040" quench, 200¬? @ .050" lift cam, iron head, sea level operation.

9.5:1- Same as 9:1 except aluminum head used. Light vehicle and no towing.

10:1- Used and built as the 9.5:1 engine with more than 220¬? @ .050" lift cam.

10:1- 4" and smaller bore, high RPM cam, cold plugs, good fuel distribution, full power limited to 30 seconds W.O.T.

1980_Cj7

09-24-2006, 05:52 AM

Oops, I forgot to add the 15 degrees to the intake closing point when I did the calculations.

Wasn't stock compression ratio for the 401 8.5:1? Is that static CR that they list? If so, I wonder what the dynamic CR is on a stock 401.

Blown7

09-24-2006, 07:43 AM

For comparison, here are the stock AMC V8 cam specs taken from my 1977 technical service manual:

'74-78 304
'74-'74-79 360 ' 74-78 401
Lobe lift .266" .286"
Valve lift (1.6x) .426" .458"
Intake valve opens 14.75* BTDC 25.57* BTDC
Intake valve closes 68.75* ABDC 90.75* ABDC
Exhaust valve opens 56.75* BBDC 80.80* BBDC
Exhaust valve closes 26.75* ATDC 42.75* ATDC
Valve overlap 41.50* 68.32*
Intake duration (adv) 263.50* 296.32*
Exhaust duration (adv) 263.50* 303.55*

Lobe separation angle
(computed by me, error-prone) 111* 115.8*

Stolen from another site, I don't have my TSM at home
http://www.jedi.com/obiwan/jeep/wagoneer/401/cam.html
Yes stock SCR is 8.5 to 1
Jeff

82Waggy

09-24-2006, 08:09 AM

Yes, the CR recommendations listed by KB are static ratios.

1980_Cj7

09-24-2006, 09:00 AM

Blown7

09-24-2006, 09:06 AM

Jeff, I'm trying to compare the stock cam to our cam, and also use the calculator to see what the dynamic CR is on the stock engine. Why are there two sets of numbers after each event, like intake opening 14.75* and 25.57*?
First number is 304/360 engines and the second is the 401, the cut and paste didn't work well with my computer if you click on the hyperlink the box comes up correctly.
Jeff

AMX69PHATTY

09-24-2006, 10:47 AM

WOW ! - 6.3 Dynamic Compression !?!?!?!? for a stock 401 :shock:
did I get sumthin' wrong ???? - fixed intake closing angle - ( thanks 82Waggy )

For a stock 8.5:1 AMC 401 camshaft I assumed a 30.75* Intake valve closing ramp,
subtracted from 90.75* in the AMC Manual ends up as 60* ABDC @ .050 lift.
The Badger Piston dish spec I have of .300 is pretty dang gone deep !
I guessed at the stock Piston Volume of 40cc's to get the 8.5 Static CR.
Unbelievable stock Dynamic CR is only 6.3:1 !!!!
If this was common, no wonder smog motors where so dead.
I assumed you started with a post '72 8.5:1 CR 401 Motor ?
I have a stock '73 401 sittin' in my garage waitn' for the next time.
Crank turms twice per one Cam revolution, Cam angles are in crank degrees.
Cam spec angles designate the valve events and corresponding crank position.
ATDC = After Top Dead Center
BTDC = Before Top Dead Center
ABDC = After Btm Dead Center
BBDC = Before Btm Dead Center

http://mywebpage.netscape.com/SketchKT/AMC+401+Stock+SilvoLite+Comp+Ratios+Fixed.jpg

Blown7

09-24-2006, 11:06 AM

Now I think we are getting somewhere. Are those numbers accurate?
If I had to pick a cam for a engine, slightly warmed it would be this Engle cam
5056-H K-56HYD .538"
.538" 272¬?
272¬? .336"
.336" 224¬?
224¬? 110¬? $160.00
New .904" Lifter profile for midrange torque, slightly rough idle 9.0 to 1 compression power from 1500-5500 RPM
with 9.1 pistons, timed straight up.
http://207.178.130.99/catalog/search_results.php

Jeff

82Waggy

09-24-2006, 11:08 AM

Yes, you got something wrong. You added 15 degrees to the actual intake valve closing point, not the closing point at .050 which is usually wrong anyway.

1980_Cj7

09-25-2006, 05:15 AM

Man, this stuff has my head spinning faster than the camshafts we're talking about. I was hoping maybe somebody out there has a warmed up 401 that runs on pump gas and could tell us what they used. All this theory is fine, but until you fire it up and step on the gas, it is still all just theory. There's nothing like actual results and experience.

Don't take this the wrong way. I'm not saying you guys don't know what you are talking about. It's obvious you do, but most of the engines you are building are for a different purpose, and way more sophisticated, than what we are trying to accomplish. I'm also smart...smart enuff to know there's no way I'm going to become an engine designer or camshaft expert overnight.

82Waggy

09-25-2006, 06:15 AM

It's not just theory. Most of it is good sound practice. You want to reduce the potential for detonation; run a quench distance beteen .040 - .050, polish the chambers, and keep dynamic compression reasonable.

The tools have been shown to you so that you can work this out for your circumstance.

You want to prevent piston scuffing; ensure a round bore and proper wall clearance.

All of the above applies to any engine. The rest is up to you.

Goose

09-25-2006, 08:27 AM

See CJ-7.. this is where all that foolin around with calculators in school leads.. (sorry guys.. :wink: )

If you want an old school opinion..you have already decked the block a bit and had the heads milled right?..well then you have bumped the compression some, and probably (in spite of all the theory to the contrary..) are going to get into detonation issues if you go much past 10.5 to 1.. so heres my humble opinion. take this block to another machinist tell them what went on, have them clean those bores up and get a set of pistons for it.. just maintain a conservative .009 or a little more clearance and go.. (at this point you have to realize that no matter how many guys shake thier heads at thier charts and theorys.. ) the facts are you have had mechanical contact between two moving pieces of machinery..(pistons/walls) so A. the clearances were too tight and B. if those pistons you had in there are going to require a 15 minute warm up cycle to stop this do you want to bother with it..?? just a humble "old school" it has worked for me opinion

Soo Listen to the Goose 'Make dem holes round and loose'...sheesh sorry had a Jesse Jackson moment there.

Goose

09-25-2006, 08:31 AM

oh and by the way..I in no way mean to denigrate the opinions of those learned ones here who actually understand all the stuff they have put out here trying to help..When I get ready to build a full on BIG power engine..I'll be talking to them..until then just reading all that I felt 'sorta like a Chimp looking at the space shuttle.. :oops:

1980_Cj7

09-25-2006, 09:23 AM

Goose, I agree on the solution to our piston scuffing. What I'm trying to decide now is what new pistons to buy, and whether to stick with this cam or get a different one, in order to be able to run pump gas.

Sounds like you're saying get stock CR pistons, the way you mentioned that with what's already been done, the CR will already be a little higher.

You're saying keep it under 10.5:1. Others are saying we need to be under 8:1. Then there's the static and dynamic deal. I'm starting to look like that chimp, ha, ha.

That's why I'm saying I just wish I knew someone who had one something like what we're trying to end up with together and running, tried and true, so we could just play copy cat. We can't afford to screw up again. Heck, we can't even afford the first screw up.

And I too am not putting down the guys on here who understand this stuff and have been working so hard to help us. In fact, I'm jealous, but for now it's still over my head. I'm learning a lot though. Thanks again for the help everybody.

82Waggy

09-25-2006, 09:32 AM

Perhaps the assumptions given were wrong? Aside from fixing your piston scuffing problem I thought you wanted to run as much compression as possible that would live on pump gas, and that you were building a motor for your Jeep which suggests bottom end torque is the goal - the commonly accepted static cr limit for pump gas with iron heads is about 9.25:1 and you need to ensure that the intake valve does not close to early so as to shoot dynamic compression above 8:1.

Quench and chamber surface are everything when it comes to controlling potential detonation.

Nothing special about what has been suggested. You can use the calculator to do the math or do what others have done that arrived at the same end, such as the use of KB 354 pistons with proper bore clearance and open the heads up to about 62-65CC's with an .045 thick head gasket - should put you right in the ballpark for compression and quench.

Here's what my 401 spec'd after machining:

Bore = 4.205 (.040 over)
Deck = 9.201 (.007 removed from deck)
Reconditioned Rod Length = 5.855
Reconditioned Crank Stroke = 3.675
KB Piston Compression height = 1.510
Piston Dish CC = 28
Head Gasket Bore = 4.275
Head Gasket Thicknesws = .045
Piston to Deck Clearance = -.002 (Above Deck_
Resulting Quench distance = .043
Chamber CC = 65
Intake Closing deg = 60
Static CR = 9.13
Dynamic CR = 7.57

Your final machining may vary slightly so use the calculator to see what you got, but it should be close as I had to mill off .007 deck height to clean and square the block - yours was probably milled less in which case you won't have to open up the head chambers as much as I did to keep compression in check and a few thousandths piston height either way won't make a whole lot of difference.

Not much else to say.

AMX69PHATTY

09-25-2006, 10:22 AM

It sounds like high Dynamic Compression may have been part of the problem.
This is a result of the intake valve closing angle of the Clevite Cam.
The Clevite Camshaft has an Intake Closing angle of only 34 degrees @ .050.
To lower the Dynamic Compression you need a different Camshaft.
The SilvoLite page calculator suggest getting a different camshaft with an
Intake Valve closing angle of a minimum of 45 degrees ABDC @ .050 Lift.
Remeber, on the SilvoLite calculator 15* has been added to the cam value at .050 lift.
The more this angle is greater than 45* on the CAM, not in the Silvolite Calculator,
60* or more in the Calculator, the lower the Dynamic Compression will be.
Using nominal values, looks like Ross and KB pistons give about the same static compression.
If the Rods are a little shorter, by .003, this will lower Compression.
If the Deck and/or Heads have been milled, this will raise compression.

My 365 motor, 0.000 deck, dished cast pistons, had 9.53:1 Static CR and 7.93:1 Dynamic CR,
was always ran on pump premium gas, and had no Detonation problems.
The cam in this motor had an Intake closing angle of 45 degrees ABDC.

:t:

ROSS Forged Pistons
http://mywebpage.netscape.com/SketchKT/AMC+401+Ross+Pistons+8DCR.jpg

KB354 Pistons
http://mywebpage.netscape.com/SketchKT/AMC+401+KB354+Pistons+8DCR.jpg

82Waggy

09-25-2006, 02:21 PM

Perhaps an explanation of the difference between static and dynamic compression ratios is in order.

Static compression ratio assumes that the piston compresses the intake charge from zero degrees BDC to zero degrees TDC - the full length of the stroke - this does not actually happen because the intake valve is not closed until some point after the piston has passed through zero degrees BDC. Because of this there is some backfeeding through the intake valve that is relieving compression until the valve has closed fully. It is the point of crank rotation at which the intake valve is fully closed, measured in degrees After Bottom Dead Center, that compression can actually begin and this is what is reffered to as Dynamic Compression.

As you can see it is the Dynamic Compression Ratio that actually controls cylinder pressure. Therefore, it is important to choose a cam that is compatible with the static compression ratio of the pistons so as to not build too much cylinder pressure.

Many will recall the muscle cars of the late sixty's/early seventy's that claimed compression ratios of as much as 12:1. Even my 69 Javelin 390 has a static ratio of 10.25:1, but these engines used large duration cams with late intake valve closing points to limit dynamic compression ratio in order to run on the premium leaded pump gas available in the day - they would have a tough time on todays lower octane unleaded fuels.

Low compression engines are a different story. Many aftermarket cams are designed to help build cylinder pressure by closing the intake valve earlier than stock in order to build additional power. Combine one of these cams with higher compression pistons and you will likely exceed usable limits, as has been shown earlier in this thread.

1980_Cj7

09-25-2006, 04:46 PM

Yes, you got something wrong. You added 15 degrees to the actual intake valve closing point, not the closing point at .050 which is usually wrong anyway.

So when I'm using the Silvolite calculator, I should be using cam specs based on .050 events, right? So since the cam specs that AMX69Phatty posted for our Clevite cam say the intake valve closes at 34* ABC at .050" lift, I should use 34 + 15 or 49*, right?

Sounds like the stock cam specs aren't at .050 because of how AMX69Phatty deducted to get an assumed .050 event.

82Waggy

09-25-2006, 04:55 PM

CJ7, You are correct. It should be the closing event degrees at .050 plus 15 - or 49 as you have indicated.

Your cam card should specify when the intake valve closes. Another way to determine when the valve closes is to take 1/2 Advertised Duration Plus the intake Lobe Centerline angle minus 180 degrees to come up with the closing angle After Bottom Dead Center. In this case you would not add the 15 degrees when using the calculator.

Note that adding 15 to the .050 closing event on any cam is a guess. The actual closing event may be more or less degrees away from the .050 event.

AMX69PHATTY

09-25-2006, 09:54 PM

1980_Cj7, yes, for your Clevite Cam I used 34* + 15* = 49*
in the SilvoLite Calculator and it gave a Dynamic Compression of 8.63:1
with the Ross pistons you have, and a Static compression of 9.7:1

When I changed the value in the SilvoLite Calculator to 60 degrees,
which assumes a cam with a .050 Intake closing spec of 45 degrees ABDC
and then add the 15 degrees to that SilvoLite says to, and use 60 degrees
in their calculator, I then got a Dynamic Compression of 8.0:1 thereabouts.
And this was with the same Ross pistons and Static CR of 9.7:1

The KB 354 pistons come out more or less the same as the Ross units
because the KB's are a little taller but have a larger dish volume.

I'm amazed with all of this cause my 365 Motor had no detonation problems.
Per the SilvoLite calculator it had 9.53:1 Static and 7.93:1 Dynamic Compression,
and when I just checked, the cam had an Intake closing angle of 45 degrees ABDC @ .050 lift !
I did not do that on purpose when the 365 was built, but it looks like I was just dumb lucky :?
WOW ! I'm amazed ..... :shock:

So it sounds like if you find another cam with an Intake closing angle
of 45 degrees or more ABDC @ .050 Lift you could be good to go with the parts you had.
Of course open up the bores on the pistons for more clearance.
It looks like the Clevite Cam was designed to create more Dynamic Compression
in a motor that was stock or built with LOW Static Compression.
Over the counter aftermarket replacement 401 cast pistons are for 8.5:1,
but your motor already had HIGH Static Compression with the Ross Pistons,
and therein is where the problem llies, ....... it seems ( escape clause :wink: )

Blown7

09-26-2006, 03:23 AM

1980_Cj7,
but your motor already had HIGH Static Compression with the Ross Pistons,
and therein is where the problem llies, ....... it seems ( escape clause :wink: )

You don't need a escape clause because that was the major problem , and I will go so far to speculate that the cam was timed wrong ,and if it was installed in the retarded position it probably had even higher dynamic compression then the calculator shows.

Jeff

82Waggy

09-26-2006, 06:27 AM

You meant advancing the cam would close the intake valve earlier.

Here is an interesting article on cam selection - probably more than you want to know. http://www.compcams.com/Community/Articles/

Scroll down to the article titled "Be The Camshaft Expert".

I'm going with a custom grind from Crower for my 401, similar to their part number 45241, http://www.crower.com . This cam has an actual intake closing point of approximately 65 degress ABDC and would work well with a static compression ratio in the 9.5:1 range.

1980_Cj7

09-26-2006, 06:47 PM

We have a brand new Comp Cams camshaft sitting here (not the one that is currently in the engine). Here's the specs on it. Just when I thought I was getting a handle on some of this stuff, now I'm seeing new things like "valve timing at .006" and "cam installed at 106 intake clearance" and "duration at .006 tappet lift". What does that mean, and would this cam be any better? I'm thinking not. Seems like a little too much lift and duration, and the intake closes only 6* latter than the one we have in now (if that .006 is the right value to be looking at).

I was going to run the calculator, but I'm uncertain of some of the terms and what values I should use.

Camshaft Specification Table
Part Number 10-210-4
Engine 1966-1979 American Motors Co.
290ci-401ci
8cyl.
Grind Number A 292H-10
Description

--------------------------------------------------------------------------------

Intake Exhaust
Valve Adjustment 0 0
Gross Valve Lift 0.518 0.518
Duration At 0.006 Tappet Lift 292 292

--------------------------------------------------------------------------------

Valve Timing At 0.006
Open Close
Intake 40 72
Exhaust 80 32

--------------------------------------------------------------------------------

These Specs Are For The Cam Installed At 106 Intake CL
Intake Exhaust
Duration At 0.05 244 244
Lobe Lift 0.3235 0.3235
Lobe Separation 110

--------------------------------------------------------------------------------

Recommended Valve Springs 986-16

82Waggy

09-26-2006, 07:19 PM

Way too much duration for what you are trying to do- you would have no bottom end power.

Read the article I listed above. It will clear up a lot of the questions you have on cam specs.

CL = Centerline, not clearance
The intake valve closing point is 72 deg ABDC
.006 refers to tappet lift and is used for the duration spec here because hydraulic lifters spring about that much before the valve begins to move.

AMX69PHATTY

09-26-2006, 08:19 PM

Not sure if this cam would work for you or not. :-|
Cam suppliers list working rpm ranges, but any one given cam
listed for an AMC also says it's for anything from a 290 to a 401, 111!!!
so since yours is a 401 I would think the power band would be lower.
Do you have a Cloyes True Roller Timing Chain with the 4* Advance & Retard Keyways ?
If so, you could install this cam 4* Retarded, giving a 44* Intake closing @ .050 Lift.
Although Retarding the Cam does shift the power band RPM range upward.
It does have less duration, 228* IN / 235* EX @ .050, than the Crower.
It may be a little "radical", but putting it in a 401 would "tone it down" a little.
I think you can order a cam ground to whatever specs you want from any supplier.
They pretty much don't grind an AMC Cam until they get an order for one anyway.
Maybe try calling Crane, Crower, Iskerdian, Lunati, or whoever you prefer and ask'em.
:t:
Cam Suppliers give their specs in at least 2 different ways.
One is called "adverised" duration, which is usually at .004-.006 lift.
The other duration spec which is kinda "standardized" is at .050 lift.
The area on the cam lobes between these two durations is called the "ramp".
This is the area where the valve is opening and closing on the valve seat in the cylinder head.
During this time between .004 and .050 valve lift air flow is negligble.
The .050 lift is used as a standard so a person can compare one cam to another.
Cause if one suppliers specs are at .002 and anothers at .008 one can't compare'em.

http://mywebpage.netscape.com/SketchKT/AMC+Cam+Lunati+31702.jpg

fuzz401

09-27-2006, 05:20 AM

that cam is close to what I have
Grind Number A 292H-10

1980_Cj7

09-27-2006, 05:50 AM

Read the article I listed above. It will clear up a lot of the questions you have on cam specs.

Yes, I glanced at the article, but just didn't get chance to read it yet. Looks like a really good article with lots of great supporting illustrations. I'm looking forward to studying it. Thanks for the link.

82Waggy

09-27-2006, 06:33 AM

The Comp 292H is for 2500 - 6500 RPM with 10:1CR in a 360 & up engine. Definately a bit out of range for a good torquey Jeep motor.

For a Jeep I would be looking for something spec'd in the Off Idle to 4500RPM range, which probably means something in the 260-270 adv duration category in a 401, with lift approaching .500" - but that is far from everything you need to spec for a cam.

Just for an example, the Crane H-260-2 might come real close to fitting the bill.

CRN H-260-2
Rocker Ratio 1.6, 1.7
LCA 108
LSA 112
Intake Adv Duration 260
Exhaust Adv Duration 272
Intake Lift 456, 485
Exhaust Lift 484, 514
Intake Open, ATDC -22
Intake Close, ABDC 58
Exhaust Open, BBDC 49
Exhaust Close, BTDC -43
Overlap 65
Above at .006 lift

AMX69PHATTY

09-27-2006, 07:49 AM

Connecting Rod Bearings with Oil Squirter Hole
If you Cranks Connecting Rod Journals are ground .010 Undersize
I believe you may be able to get Connecting Rod Bearings with Oil Squirter Holes
from http://www.kennedyamerican.com/index.asp in Ohio (614) 879-7283
They may even be original American Motors New Old Stock Parts.
:(: CRAP - I called Kennedy American, he went and looked, NO SQUIRTER HOLES

Crane HMV-260-2-NC Camshaft
I believe the Intake Closing Angle @ .050 Lift for this cam is only 29 degrees.
Guess it looks like it's going to be difficult to find a Cam that's good for Low RPM Torgue
and that has an Intake Closing angle of 45 degrees or more.

Maybe the thing to do is get the good ol' Cast stock type 8.5:1 Replacement Pistons.
If you need to replace the Pistons, they are the least exspensive and more practical
and would also solve the Dynamic Compression Ratio "problem",
and you could go ahead and use the Clevite Cam you already have.
That way, it would then definitely be ok to run on pump gas.
:-|

82Waggy

09-27-2006, 08:02 AM

The intake closing point at .050 +15 is inaccurate.

Use the actual closing point of 58degrees ABDC and don't add or subtract 15 when using the KB calculator.

fuzz401

09-27-2006, 08:31 AM

he could go 8.5 and use 291 heads to bump it up a little

fuzz401

09-27-2006, 08:53 AM

my motor with 15 added

ENTER YOUR DATA CALCULATED DATA
Cylinder Head Volume (cc) Cylinder Head Vol
(cubic in.) 03.660
Piston Head Volume (cc) Piston Head Vol
(cubic in.) 00.732
Gasket Thickness (in.) Swept Volume
(cubic in.) 50.863
Gasket Bore (in.) T.D.C. Volume
(cubic in.) 04.659
Cylinder Bore Diameter (in.) Gasket Volume
(cubic in.) 00.267
Deck Clearance (in.)
Note: Neg. nubmer above deck, Pos. number below deck Deck Volume
(cubic in.) 00.000
Stroke (in.) STATIC COMPRESSION RATIO 11.917

OPTIONAL DATA
Rod Length (in.) Adjusted Stroke (in.) 02.934
Intake Closing Point (degrees)
ABDC @ 0.050 lift plus 15 degrees DYNAMIC EFFECTIVE COMPRESSION RATIO 09.704

with out 15 added
ENTER YOUR DATA CALCULATED DATA
Cylinder Head Volume (cc) Cylinder Head Vol
(cubic in.) 03.660
Piston Head Volume (cc) Piston Head Vol
(cubic in.) 00.732
Gasket Thickness (in.) Swept Volume
(cubic in.) 50.863
Gasket Bore (in.) T.D.C. Volume
(cubic in.) 04.659
Cylinder Bore Diameter (in.) Gasket Volume
(cubic in.) 00.267
Deck Clearance (in.)
Note: Neg. nubmer above deck, Pos. number below deck Deck Volume
(cubic in.) 00.000
Stroke (in.) STATIC COMPRESSION RATIO 11.917

OPTIONAL DATA
Rod Length (in.) Adjusted Stroke (in.) 03.252
Intake Closing Point (degrees)
ABDC @ 0.050 lift plus 15 degrees DYNAMIC EFFECTIVE COMPRESSION RATIO 10.647

82Waggy

09-27-2006, 09:19 AM

fuzz401

09-27-2006, 09:31 AM

http://img.photobucket.com/albums/v31/fuzzcj7/camcard401.jpg

82Waggy

09-27-2006, 09:52 AM

Yup, like I said, the actual closing point is more like 72-75 deg ABDC depending upon how you degree'd your cam.

I can't tell how you arrived at your static numbers in the calculator either. What Pistons did you use - dish size, compression height, bore?

Just guessing looks like you will be under 8:1 DCR.

1980_Cj7

09-27-2006, 11:32 AM

You guys are missing it.

DO NOT USE THE .050 CLOSING POINT AT ALL.

Use the actual closing point at .006 for a hydraulic cam.

Fuzz, your closing point has got to be around 70degrees ABDC with that kind of duration. For the Comp 292H-10 the intake closing point is 72deg ABDC.

I think I'm finally catching on. If you use the closing point at .050, you add 15 degrees. If you use the actual closing point, which is the one listed as at .006, you don't. The reason it is at .006 is for the "slop" in the hydraulic lifters. Do I have it right?

But, what do you use if you don't have hydraulic lifters, like Fuzz?

Can't wait to get chance to read that article.

That's weird. Looks like when Fuzz tried to cut and paste the Silvolite calculator, it came out all screwy just like it did for me. Yet when I cut and pasted it in an email to Silvolite, it came out perfectly.

82Waggy

09-27-2006, 11:46 AM

You got it.

For Fuzz it is really about the same. Mechanical lifters have lash (a gap between the pushrod and the rockers). Mechanical cams spec valve events based upon some assumed lash (like maybe .020 valve lift instead of .006 for a hydraulic). Duration and lift figures may not be quite as accurate depending upon how much lash you actually have in the valve train as installed verses the standard used to spec the cam, but it is still close enough for guestimating purposes.

I think the cut and paste problem is due to an incompatibility between the HTML calculator and plain text in this forum.

82Waggy

09-27-2006, 12:00 PM

BTW:

jeeps4ever just pointed out another build to me. If you want to see another example of a combo that works on pump gas, check out donwags 401 write up in the general chat section of this forum.

He used a less than 260 duration cam with a static CR of around 9:1 and dyno'd over 400ftlbs torque at 2000RPM!!!!!

You can do the same thing with your heads and the KB pistons. Just zero deck or close to it, polish your head chambers out to to arrive at around 9 - 9.25:1 SCR and run a cam like donwags or the Crane I pointed out above. I'm doing nearly exactly the same thing.

Blown7

09-27-2006, 04:53 PM

Now I think we are getting somewhere. Are those numbers accurate?
If I had to pick a cam for a engine, slightly warmed it would be this Engle cam
5056-H K-56HYD .538" 272¬? .336" 224¬? 110¬? $160.00
New .904" Lifter profile for midrange torque, slightly rough idle 9.0 to 1 compression power from 1500-5500 RPM
with 9.1 pistons, timed straight up.
http://207.178.130.99/catalog/search_results.php

Jeff

Maybe it's me I think I posted this about 5 pages ago :-|
And now were getting back to it?

Jeff

Blown7

09-27-2006, 04:56 PM

fuzz401

09-27-2006, 05:08 PM

ross flat top's 0 deck
http://img.photobucket.com/albums/v31/fuzzcj7/IMG_0496.jpg

82Waggy

09-29-2006, 10:59 AM

Pretty cool Fuzz!

Regarding cams, I think most go too long on duration. For a Jeep or a truck I would think you would want to keep the torque peak in the lower RPM range by using something on the order of 260 degrees intake duration. Take a look at the dyno numbers that donwag got with his 9:1cr 401 build using a Comp XE256 - over 400ftlbs at 2000RPM with peak torque of 427ftlbs at 3600. That's right where you want it. The Engle 5054 would work well too, with an intake closing point of 58deg ABDC, 260dur, 501 Lift!!!!.

Durations of 270 and up would be more appropriate for a light street car or an engine with over 9.5:1CR.

Holeshot

09-29-2006, 12:32 PM

Too bad the heads were designed to flow well at 6000~6500 RPMs!!!!! (even better than the Chevy "Turbo" heads)

For those who don't get that, smaller ports/valves flow better at low revs, losing out at higher revs, bigger ports/valves flow better at high revs, losing out at low revs.

Would have been better for you low RPM guys if AMC would never have started putting the big valve/big port "dogleg" heads on!!!

I guess you could stick with 304 heads & let us guys who like 500+ ft.lbs. of tq & 500+ HP & 6000+ RPMs have the 360/401 heads, eh???

I imagine it would be possible to put the '69 & prior heads on your low-po engines for even more low RPM torque.

:razz:

82Waggy

09-29-2006, 12:57 PM

Nothing wrong with good flow at low RPMs either.

This thread is about a daily driven jeep motor, not a dragster.

The point is that too much duration is not good for torque at low R's, and in fact lowers what may be acheived in the lower RPM ranges for a given CR.

And since you brought it up, valve diameter to displacment ratio for the AMC ain't all that good (SBC is better), so you would not want to go smaller than the standard 2.025,1.65 valves for the 360-401.

Goose

09-29-2006, 05:27 PM

Heh Heh.. :wink:

Umm holeshot. you miss the point..moving the peak torque/hp down in the power band is as valid as building a high rpm "Breather"..no need to look down on us "Lo-PO" guys and really I have looked into this.. and it isn't a sin,sacralidgeous or even unfashionable, to build an engine for the intended purpose of the vehicle. I cant begin to imagine why you have such a problem with this..It's ok to not extract the last ounce of hp or rpm out of an engine, really truly.

Holeshot

09-29-2006, 06:44 PM

Nothing wrong with good flow at low RPMs either.
Very true - but heads designed to flow well at high revs will never have as high velocity at low revs as small port heads, losing low speed torque to the small heads.

The 1970 + head was designed with large, good flowing ports & large valves, intending to win races at high RPMs.

The 291c type ports are competitive with the early hemi when fully ported, polished, & big valved.

Large, high flowing ports necessarily are not as good down low as small ports. It is pretty hard to make large ports smaller. You should get some low speed velocity back by using the small valve 304 heads, although I have never seen the flow number for the little heads.

Goose, you are missing the point, moving the peak down the power band DETRACTS from the design of the heads. The heads are designed to flow well, which means that they will not have as high velocity at lower revs as smaller ports would have, meaning smaller port heads (290/304) will have MORE torque down low than the larger 291c style heads.

And since you brought it up, valve diameter to displacment ratio for the AMC ain't all that good (SBC is better), so you would not want to go smaller than the standard 2.025,1.65 valves for the 360-401.
Any engine that is run so slow that it never exceeds the flow capacity of a certain sized valve does not need a larger valve and will lose low end performance with larger valves. I always go for 2.08/1.74 & will go bigger when I can afford it!!!

My point is, that if I build a 401 to ENHANCE the performance of the heads, I can get over 500 ft.lbs. of tq. (400 ft.lbs. just above idle) & over 550 HP BOTH (6500~7000 redline), where the low RPM build will max out at around 300 HP, well over 200 HP LOST to the 2500~6500 powerband build.

Don't blame me for the laws of physics!!! Small ports will make more tq down low, big ports at higher revs!!!

AMX69PHATTY

09-29-2006, 08:37 PM

82Waggy

09-30-2006, 05:47 AM

Runner volume is the same in the smaller valve dogleg heads.

Holeshot is correct that high velocity is generally better for low RPM torque, but runner size must also be balanced against displacement - Dogleg head runners are not too big for a 401.

Bottom line is that more cam duration simply moves the torque curve up the RPM range - for a given CR you will generally lose bottom end torque as duration increases.

Building for in excess of 5500 RPM's also requires a considerable level of additional effort and such high RPM is generally not useable for off road or daily driving.

Holeshot

09-30-2006, 07:54 AM

May I ask, in dogleg exhaust port style heads, are not the runner volumes
the same in the 304, 360, 390, & 401 Heads, just the valves are smaller
in the 304 heads, at least in 1970 anyway ?
I had thought that the heads were identical except for the valve sizes, so I started going through my AMC tech data, and found in the "AMC Power Book" by Martyn Schorr, several different places where the various contributors stated that the 304 heads had smaller ports and smaller valves. It would be worth CCing them to be sure, the crawler guys could use smaller ports and valves to some advantage.

Or are you saying the runner volume is less in the '69 & earlier rectangular exhaust port heads ?
The early heads are entirely different design and castings, I certainly would not expect that the ports are as large as the late heads, since the late heads are so much better. I, of course, have NO use for the old heads and long ago exiled them all to the dump. They too, may be an advantage to the crawler guys and I'm sure it would not be that hard to adapt them onto the late blocks, 290s having the small valves, would also be advantageous to the crawlers.

Goose

10-01-2006, 08:00 PM

Fer cryin out loud..tell ya what, you scare up some of these "Little" heads and I'll swap ya mine.. until then I'm gonna spend my money to build an engine that performs the task I set for it.. not to some theoretical esoteric best case B/S. I use the AMC cause I like it and because it is what came in the jeep.. If I wanted a theoretical perfect engine for the task I would build a 500 CUBE CADDY and put it into a flatty.. then I could flip the damn thing over in the drive way by revving the throttle in nuetral and bust EVERY joint in the drive train at the same time.. It would save time since I don't seem to be able to build enough Horsepower to hurt any of the 3 of my jeeps..in the last 25 years.. (of course it could also be a smattering of common sense and restraint.) So If I build a "big head AMC" and get the same or greater performance than say a 400 chevy..How is that wrong?? we "crawlers" overcome the "Disadvantage" of the AMC's head design and flow characteristics by using (Shudder) small runner intakes or spread bore small cfm carbs..not 1150 cfm toilet bowls.. these engines need crisp throttle response and power in the real world rpm bands not the wide open throttle area. because it is Theoretically possible to make more rpm by spending a butt load more money.. why would I do it when I dont need RPM?? Just to say I did?

82Waggy

10-02-2006, 09:58 AM

That's what I call "Cleaning & Frying", Goose! :?

Holeshot, even the large valve dogleg heads are not oversized for the displacement of a 401. Relative to the 1.94 valve SBC 350, even the larger 2.08 valve available for the dogleg head is actually smaller per the displacement of a 401 - making the 2.025 valve dogleg head an excellent torque producer - even at low R's.

I still can't get over the wide and flat torque curve of donwags 401 with a .477,488lift, 256, 268dur cam - over 400 ftlbs, from 2000 - 4400rpm, with a peak of 428 at 3600. That's freaking good on pump gas no matter anybody else says.

Could probably even get a little more torque and extend the RPM range if you wanted to with a little more valve lift. If there is one nice thing about an AMC, it's their large diameter lifters that allow you to keep duration short and lift high.

AMC's are great Jeep motors no matter what others may think.

Holeshot

10-02-2006, 02:34 PM

Building for in excess of 5500 RPM's also requires a considerable level of additional effort and such high RPM is generally not useable for off road or daily driving.

My stock 48,000 mile '71 360 AMX (with 401 cam, Crane springs, Accell ign, headers, Torker, & 750 Holley) turned 6500 RPM every day (until the float bowls went dry, every 11 seconds or so, or at around 110 MPH). Never broke until over 100k when the bearings & timing chain went big. It had no internal mods of any kind!!

Take a breath Goose!!! :razz: I didn't mean to imply you (guys) were doing anything wrong!!!

Sorry if it seemed so, OK? :oops:

jeepsr4ever

10-02-2006, 03:13 PM

SIXTEEN PAGES OF LOVE :?: :?: :?:

Sorry guys couldnt resist :mrgreen:

82Waggy

10-02-2006, 03:41 PM

Hey Holeshot, where can I get a copy of that "AMC Power Book?

Aside from my 401 Waggy motor I'm also building a 390 street screamer for my Javelin. That book would be an interesting read.

Holeshot

10-02-2006, 04:14 PM

I got my copy off of Ebay, I do believe it was from Eddie Stakes down in Texas...click on the "Literature" link in the menu column of his site.

many consider it to be 'Part II' of the Performance American Style AMC Speed 'bible'. $13.00 + $2.50 Shipping

http://planethoustonamx.com/planethoustonamx.GIF
http://planethoustonamx.com/
http://planethoustonamx.com/parts/AMC_power_book.JPG

Goose

10-03-2006, 08:34 AM

OK I have taken your advice and administered several frosty cold adult libations..and added the ministrations of a wonderfull young lady... and poof, perspective returns.. :!: I am now a calmer more reasonable Goose with permagrin! :?: :?: 8)

:wink: It's all good..(now you know why I dont talk about politics..anymore)

Mudrat

10-03-2006, 05:25 PM

OK I have taken your advice and administered several frosty cold adult libations..and added the ministrations of a wonderfull young lady...
http://smiley.onegreatguy.net/bsflag.gif
:?:

Goose

10-04-2006, 07:23 AM

Ahhh But you forget Rat... I now reside in Little las Vegas.. 21 year old cocktail waitresses and Beeeeyoootiful Black Jack dealers...All waiting in line for thier chance at my rather roundish, slightly weathered, tired old guy butt..(Ok Maybe it's not the Butt.. could be the Boss thing..) Either way...Lift? Duration? Runner length? unshrouded.. yea they take on a whole new meaning in this a more enlightened moment.. 8) 8) .

Oh and since I am a world class surveillance guy FILM AT 11 !!!

1980_Cj7

10-09-2006, 10:20 AM

Well, never heard anything from the new machine shop, so I called them, again, for the third time. He said he looked at it and can't say why what happened happened. He said the only thing we can do is go .040 over. I told him AMC specs say not to go more than .025 over, and that we didn't want to go that much over. I asked didn't he think the cylinders would clean up with just a honing, especially since they were on the tight side. He said he could try and see what happens. He said if not, we could always sleeve it. Don't really want to go that route though.

I asked if he had checked the cam to see if something was wrong that was causing that weird timing problem. He said he hadn't but would.

82Waggy

10-09-2006, 10:45 AM

I went .040 over on my 401 - still plenty of wall tickness left. Most would conceed that .130 wall thickness is enough and I ended up with well more than that.

I still can't beleive that these machine shops are suggesting that .004 forged piston clearance is enough. Hmm.

Mudrat

10-09-2006, 01:48 PM

Is it snowing where you are? 'Cause it sounds to me like this guy is gett'n the wool blanket out and hasn't looked at your block at all?? Now the conversation may have been different, but it doesn't sound like he has answers, just solutions?

1980_Cj7

10-09-2006, 02:58 PM

We're going to stop at the shop and talk to him tomorrow after work. First thing I want done is the cam degreed to see if it is in right.

If it isn't, we'll be talking to the shop that put the engine together. If it is, the next step is finding out how much he wants to hone the cylinders, and if there will be any guarantee on the engine if we let him put it together. Can't afford to have this happen again.

As far as the clearance, we've had the engine looked at by 3 machine shops now, and they are all saying the clearance wasn't the problem. They all said, as did Keith Black's technician, that if it was a clearance thing, the pistons would have been scuffed on both sides, not just one side. I'm glad the clearance was on the tight side though, as maybe that will give us enuff leeway to clean up the cylinders and not have to rebore.

Only other thing I can think of is to find someone who knows AMC's and let them look at it. Maybe the place in NJ that Fuzz uses. Anybody know anybody else around Harrisburg, PA that is good with AMC's.

Blown7

10-09-2006, 04:05 PM

How far is Herman Lewis from you?

Jeff

Mudrat

10-09-2006, 04:42 PM

How far is Herman Lewis from you?

Jeff
THAT would be the man to build it for ya too!!!

fuzz401

10-09-2006, 05:22 PM

Hemmi atkins would be good to

Mudrat

10-09-2006, 05:57 PM

Fuzz :shock: You changed your Avatar!!! :shock: :shock:

I'm trying to put one togther like that, but a cartoon style, not a photograph :? :wink:

http://members.cox.net/mudrat-jeeper/Pat_RAT-2.gif

Holeshot

10-11-2006, 06:27 PM

AMC Power Book ($13) on ebaY....
http://cgi.ebay.com/AMC-Power-Book-AMX-Javelin-Jeep-Group-19-401-390-360_W0QQitemZ330038104654QQihZ014QQcategoryZ4150QQ rdZ1QQcmdZViewItem

Long since out of print the AMC POWER BOOK! A copy of my original, this thing will pay for itself the first time you use it. A fantastic book for those do it yourself AMC & Jeep fans. Topics include: 68 AMX; 69 Hurst SC/Rambler; 70 Hurst Rebel Machine; 290-401 basic performance tips; CARS magazine Project Super Javelin; 302 Trans Am specifications; How to build a hot stock 343; how to build a super street 370; how to build a 390 Enduro motor; Pro Stock engine combinations; How to blueprint 390 heads; Grant's fuel funny Rebel; AM factory speed equipment guide (Group 19). Tons of illustrations, specs, crammed in the 50 pages. Last published in 1977; a nice addition for your collection, again, this is just a copy of my original, and they are very difficult to find in any condition almost 30 years later.

http://i13.ebayimg.com/03/i/00/c4/6d/ae_1.JPG

AMX69PHATTY

10-12-2006, 09:36 AM

Just for reference, I called and talked to Dana Corp Tech Support today
who makes Clevite 77 Rod Bearings for AMC's and everyone else.
They said YES, they no longer put in the notches for the oil squirter holes.
The OEM's quit doing it, and they followed suit starting in 2003
because the OEM's found there was sufficent Piston Pin oiling from Crank windage,
and elimination of the squirter notch reduced manufacturing costs.
They also said the squirter used oil volume and hurt oil pressure,
and they eliminated it from Rod Bearings for all makes of engines.
This is what someone in this thread has already told us, thanks,
but since I was curious, I called the Bearing Manufacturer and asked.
The part number on the 360 +.020 Connecting Rod Bearing Box I have is
CB-960 P-20(8) with a Federal Mogul interchange part # of 8-3310CPA20
and the date code, 03J22CD1, appears to be 2003 ! so I'm not sure if mine have notches or not.
Motor is on the stand and not sure if I'm gonna pull a cap and look or not,
cause I'm just curious as to if the bearing I have are notched or not.

I've had difficulty having engine shops "check" things too.
They seem to just want to go to the next oversize to be sure,
and the profit margin is in doing the machine work and selling new pistons,
and they're not relying on someone elses work, is my guess.

Holeshot

10-12-2006, 10:17 AM

starting in 2003
because the OEM's found there was sufficent Piston Pin oiling from Crank windage, and elimination of the squirter notch reduced manufacturing costs.

Do ya think that this could be due to the fact that AMC went out of biz decades ago and the demand for AM V8 bearings may be about equal to that of Edsel bearings???

How in the Hell do they know anything about pin oiling & windage in an AMC V8??? Do ya think they have even ONE dyno AM V8??? NOT!!!

I will go ahead and rely on AM's design, and not some Chinese reivisionist idea of what should be OK.

I'll be notching my own bearings!!!! And I won't be having any siezures!!!

AMX69PHATTY

10-12-2006, 11:38 AM

I must say I agree with you HoleShot.
Obviously there are varying opinions on this detail.
Be nice to have a "how to" section in this forum for those who want'em.
Or maybe even have modified pieces available at the BullTear E-Store,
of course with a "use at ones own risk" disclaimer.
But, for me at least, agree with you HoleShot.

1980_Cj7

10-12-2006, 05:28 PM

I sent Dana-Clevite an email weeks ago asking about the oil hole...and they never bothered to reply. Thanks for checking and sharing with the rest of us. I tend to agree. AMC did that for a reason, and it wasn't to save money as it cost more to make the squirter holes. Dana-Clevite on the other hand is saving money by NOT putting the holes/notches on the bearings. I'll be notching ours too.

fifesjeep

10-16-2006, 11:45 AM

Here are some pics of my goodies that are in my 360... The first pic is of the Ross 10:1 FF Racing Piston... (I wish they would stay that clean). :lo1l:
http://i7.photobucket.com/albums/y293/Fifesamcjeep82/000_0406.jpg
http://i7.photobucket.com/albums/y293/Fifesamcjeep82/000_0408.jpg
http://i7.photobucket.com/albums/y293/Fifesamcjeep82/000_0410.jpg

Holeshot

10-16-2006, 12:17 PM

Looks like she'll be a "pinger".

82Waggy

10-16-2006, 02:44 PM

Oh I dunno Holeshot, He's running a Magnum 280 cam. Ought to be pretty lumpy!

Holeshot

10-16-2006, 03:54 PM

May be, but he will never get .045" PTHC with that dish, should have used flat tops & opened up the chamber to lower the CR, not mill out a dish. I had a 390 with a big old dish like that, came out to 9.1~1, pinged like crazy. It had something like .185" PTHC, like what he is gonna have!!!

Blown7

10-16-2006, 04:17 PM

And why did this thread get Hijacked???

Jeff

82Waggy

10-16-2006, 04:43 PM

Sorry about the hijack, but now I have to respond to holeshot!

The piston dish has nothing to do with quench, it is the flat section against the head that governs this. A D-cup dish is actually good for flame travel.

holeshot is correct on the bad PTHC though. 360's and 390's are some of the worst of the AMC's in this regard, and excessive PTHC is a prime source of pinging problems.

jeepsr4ever

10-16-2006, 05:02 PM

What did you pay for the pistons?

fifesjeep

10-16-2006, 05:45 PM

I paid $650 for the pistons... (Net dome cc's is -16, Dish depth is .140)
$250 for Scat Forged Rods
$150 for the 1.7:1 Harland Sharp Roller Rockers with the relief milled on the bottom... (jumping up to the 1.7's did it justice)....
The Dynomax Headers 1 5/8" to a 3"x6" collector bolted to the 3" purple Hornies (For a JEEP it is a nice flowing system). I paid a little over $400 for the purple hornies and Dynomax headers
$450 for the Comp 280H Magnum K-Kit
So for about $2000 I figured that was a good buy/investment...
She definitely has a lumpy idle... My heads were milled .020" and I'm using a .040 or .043" headgasket??? I can't remember the thickness.. I'll have to find my papers. (I used some pursian blue and set my intake on and I think I ended up milling .005 or .007" off of it, (Per side)... It's been a while. My neighbors "Love it when I start it up!" The cops don't...
(Sorry, didn't mean to hijack thread... temptation is my weak point). But, I didn't want to run too high of compression... I have the High compression heads sitting on the work bench... (which I only paid $100 for the set). I thought about using them for my Jeep but decided to go with the larger CC heads... (mainly for Trail/mud hole usage)... I don't like paying over $6+ for a gallon of gas... and for trail usage, I'll be using premium pump gas with 3 to 4 gallons of 104 octane... (Knocking on wood as I speak/type)... My buddy has a set of flat top pistons for his 343... I was going to trade him the high compression heads for the pistons but decided not to at the last minute... (If I hold-out long enough he'll sell them to me) and then I'll build a 11:1 to 12:1 compression Jeep to run down the strip...

1980_Cj7

10-17-2006, 05:43 AM

Looks like she'll be a "pinger".

I was wondering how it wouldn't be a pinger too...until I read about its $6/gallon addiction, ha, ha.

82Waggy

10-17-2006, 07:00 AM

Back to the subject of this thread, check out

http://www.kb-silvolite.com/feature.php?action=read&F_id=52

TYPICAL DAMAGE APPEARANCE
Scoring is typically on one side of the piston (photo at right), and good skirt on other side (photo at left). An originally good skirt bearing panel has narrow, clearly limited longitudinal friction marks superimposed. The ring zone is usually undamaged.

ASSESSMENT
Unburned fuel which has condensed on the cylinder walls has locally weakened the oil film such that in narrowly limited strips a dry run occurred between cylinder and piston, which always results in long narrow friction marks.

POSSIBLE CAUSES
1) Combustion disturbances due to faults in fuel injection system or carburetor or due to faulty ignition (misfiring). 2) Loss of compression through the valves or cylinder head gasket. 3) Choke too long in operation.

fifesjeep

10-17-2006, 12:36 PM

After I broke her in I ran it off of premium with no octane and she didn't ping... :? Maybe it's luck.

1980_Cj7

10-17-2006, 02:52 PM

FuzzFace2

10-18-2006, 08:54 PM

POSSIBLE CAUSES
1) Combustion disturbances due to faults in fuel injection system or carburetor or due to faulty ignition (misfiring). 2) Loss of compression through the valves or cylinder head gasket. 3) Choke too long in operation.

3. We didn't have a choke.

So, I'm still puzzled.From what was posted about the fuel system and you saying about ‚Äúno choke‚Äù makes me say it was running to rich and washing the oil off the cyl walls.
That‚Äôs my take on it.
Dave ----

1980_Cj7

10-19-2006, 05:00 AM

The plugs looked real good though. Not carboned up at all. There are some pics above in this thread.

I always thought a choke made the engine run richer by cutting down on the amount of air in the air-fuel mix, so it doesn't seem like not having a choke would make it run rich. Also, the choke is only in play for a short time til the engine warms up.

1980_Cj7

12-01-2006, 09:54 AM

The saga continues: we told the new machine shop to go ahead and clean up the cylinders and see what we end up with. Well, they just called me. They started tearing down the engine when they noticed the camshaft key was in the rounded oil groove in the timing gear, not the keyway where it should have been! I'm sure glad they are going slow and keeping their eye out for "problems".

Now I'm trying to figure out what the effect of that would have been. First off, the divit on the back of the timing gear would not have lined up with the hole in the cam journal and would not have been letting oil thru. I didn't see the engine yet, but told them to stop right there til we came and looked at it. I think we're going to load it up and take it back to the guy who assembled it in the first place.

I did dig out the original cam and gears though and was looking at them. It looks like the oil groove and the keyway are about 180 degrees off. I'm wondering how the teeth line up with the groove and keyway. I'm thinking this may very well have been our timing problem. If you recall, we were having to run 20 degrees advance to get any kind of power, but then were getting pinging.

Any thoughts on what else this screw up may have caused? We're very interested in getting all the ammo we can to take with us this afternoon to the original machine shop.

Holeshot

12-01-2006, 10:31 AM

1980_Cj7

12-01-2006, 10:44 AM

You don't want the guy who screwed it up to get his hands on it again, do ya???

I'd say let the machine shop continue the teardown & give you a written estimate of what it will cost you to get it back to where it was supposed to be in the first place. Then give the butcher a copy. If he refuses to pay for it, sue him. It's the only way to get things put right again.

Good luck!!!!

NO WAY he's touching our engine again! We just wanted to take it and show him proof of the screw up before it's taken apart any further...and tell him we want our money back!

1980_Cj7

12-01-2006, 10:47 AM

What else gets oiled via that groove thru the timing and distributor gears besides the timing chain and the distributor gears, anything?

And to think, before I took the parts to the machine shop, I checked everything, and even opened up the divet on the back of the timing gear because it wasn't lining up with the hole in the camshaft. (Fuzz warned us to check that.) A lot of good that did.

1980_Cj7

12-01-2006, 04:40 PM

Just got back from picking up the engine from the new machine shop and taking it back to the "butcher shop". We showed the shop foreman the problem, and he agreed that they definitely screwed up. He was getting ready to unload the engine when we said no, we're having it done elsewhere this time.

We gave him the choice of refunding our money, or picking up the tab from the new machine shop to get the engine back to where it should be. He preferred the later, and didn't give us any argument, but said he had to talk to the owner. He took some pictures, and we brought the engine back with us. Fortunately, the owner is the one who assembled our engine, so I don't see how he can argue, but...stay tuned, cross your fingers, and even send a little prayer to the Big Engine Builder in the sky on our behalf.

Holeshot

12-01-2006, 04:56 PM

Don't forget that he also bored the engine too tight for forged pistons & blew them & the bore job away as well!!!!

1980_Cj7

12-01-2006, 05:52 PM

Don't forget that he also bored the engine too tight for forged pistons & blew them & the bore job away as well!!!!

Agreed, and not to mention our loss of the Jeep all summer, plus all our time and labor putting the engine in and out and back in again.

Blown7

12-02-2006, 05:15 AM

Wow that explains alot! I was wondering how this saga was going. For all the replys on all these pages I know for myself I assumed that the engine was properly assembled.

Jeff

AMX69PHATTY

12-02-2006, 09:24 AM

Wow that is amazing the cam sprocket was mounted on the oil groove rather than the keyway. I can't imagine what that would do to cam timing or how one would get the sprocket timing marks to line up. I mean it seems the cam would be 180 degrees out of phase...... hmmm.....wow.

But as far as what else is oiled, maybe the fuel pump eccentric, but other than that nothing else I believe. The heavy flat washer under the single cam bolt in the snout is what seals off this oil circuit. Make sure it is flat and smooth where it seats against the forward face of the Distributor gear.

Don't over torque this bolt, I think it's only 35 ft. lbs. and make sure this bolt isn't too long and doesn't run out of internal threads in the front of the cam before pulling down tight. Have had to grind this bolt a little shorter before to prevent this. If it's too long it can run out of good threads in the cam hole and give false torque readings when being tightened.

1980_Cj7

12-02-2006, 04:32 PM

The other thing is I wonder how tight the timing gear was. It seems like it would have had a lot of slop in it as the key didn't fit the rounded groove very well. I didn't think to check it for play, but I'm going to.

I dug out the original stock cam and timing gear to show the machine shop how it all worked, without pulling the incorrectly mounted one off until I showed the butcher shop. In the original timing gear, the oil groove is a lot smaller and there is no way you could have put the key in it by mistake.

jeepsr4ever

12-02-2006, 05:17 PM

Sure seems like they were in a hurry when they were rebuilding your 401 :oops:

Holeshot

12-03-2006, 06:18 AM

Sounds like they smoke their lunches over a twelve pack at that shop. Maybe you should name them so as to protect others who may fall into their grasp!!!

1980_Cj7

12-03-2006, 06:37 AM

Sure seems like they were in a hurry when they were rebuilding your 401 :oops:

I don't know how much actual time they spent on the engine, but the sad part is it took them forever to get it done. Caused us to miss the big PA Jeeps Show which is one of the highlights of our Summers for one thing.

Depends on how they treat us from here as to how much "publicity" we'll give them.

Mudrat

12-03-2006, 10:49 AM

Show'm this thread and then play "Let's make a deal" :wink:

1980_Cj7

12-03-2006, 01:12 PM

Just for kicks, I ran the CR calculator again using .040 over KB354 pistons with the Clevite cam we have. I adjusted the intake closing to the actual of 72 degrees ABC. Doesn't look too bad if I've done everything correctly. What do you think?

Again, our desire is to get as much power as we can out of pump gas.

ENTER YOUR DATA CALCULATED DATA
Cylinder Head Volume (cc) 58
Cylinder Head Vol (cubic in.) 03.538
Piston Head Volume (cc) 28
Piston Head Vol (cubic in.) 01.708
Gasket Thickness (in.) .045
Swept Volume (cubic in.) 51.106
Gasket Bore (in.) 4.275
T.D.C. Volume (cubic in.) 05.892
Cylinder Bore Diameter (in.) 4.205
Gasket Volume (cubic in.) 00.646
Deck Clearance (in.) 0
Note: Neg. number above deck, Pos. number below deck
Deck Volume(cubic in.) 00.000
Stroke (in.) 3.68
STATIC COMPRESSION RATIO 09.674

OPTIONAL DATA
Rod Length (in.) 5.858 Adjusted Stroke (in.) 02.676
Intake Closing Point (degrees) 72
(actual calculated from advertised duration of 294 degrees)
DYNAMIC EFFECTIVE COMPRESSION RATIO 07.308

Now, the big question is how far off was the cam when it was installed incorrectly, and how much of our problems was it causing. Maybe we should put a degree wheel on it with it installed the way it was and see what was happening, then degree it again installed correctly and see what that gives.

Blown7

12-03-2006, 05:06 PM

Now, the big question is how far off was the cam when it was installed incorrectly, and how much of our problems was it causing. Maybe we should put a degree wheel on it with it installed the way it was and see what was happening, then degree it again installed correctly and see what that gives.

At this point I would worry about just getting the engine built correctly this time or you won't make next years PA Jeep shows. Time enough ahead to degree the cam properly.

Jeff

1980_Cj7

12-03-2006, 06:25 PM

Jeff, I hear you. What I was getting at is we're trying to decide whether to use the same cam next time around or get a different one. We're trying to figure out if the problems were from the cam grind we had, or from it being installed incorrectly.

fuzz401

12-03-2006, 06:53 PM

from it being installed incorrectly

Goose

12-03-2006, 08:45 PM

I agree, the problem from having the cam out of whck like that.. (frankly I am amazed it ran..)

1980_Cj7

12-04-2006, 10:30 AM

Was just reading about the cam anti-walk kit in the sticky post on distributor gears. Would it be a good idea to install one on our re-rebuild? We have a hydraulic cam that has about 300 miles on it. Will it hurt to install the anti-walk kit on a used cam? I was thinking it might change the wear pattern between the lifters and cam.

I also want to check and make sure the front cam bearing has the groove, and the cam has the oil relief holes in the back end. Wasn't aware of these things the first time around and consequently didn't check them.

Mudrat

12-04-2006, 04:29 PM

1980_Cj7

12-06-2006, 10:21 AM

I spoke with the owner of the butcher shop - UCF MACHINE SHOP IN CARLISLE, PA and he is refusing to pay for another shop to correct and redo the motor correctly. He said that he would redo the motor and fix it at no cost himself.

I do not under any circumstances want these jokers working on my motor anymore. Does anyone know what kind of legal rights I may have? He indeed agrees that they messed it up and that it should be corrected, however he does not agree on the fact that I would like to select the new doctor.

He said "didn't I ever make a mistake?" I replied, yes, everybody makes mistakes and has bad days, but, it was more that one thing you screwed up: 1) cam installed wrong, 2) timing gear installed wrong and no oil getting to the timing chain, distributor gears, fuel pump eccentric, etc., 3) pistons installed .017" down the holes, 4) brand new rod bearings look like they have 100,000 miles on them already, and who knows what else we'll find when we continue tearing the engine apart. Plus, I'm sure if he redid the engine, we'd end up at least .040 over. The new engine shop said they'd take just the bare minimum to clean up the cylinders, then we could order custom pistons to fit.

The other thing is when we took the engine back to these clowns when it first started acting up, they looked at it and said they had no idea what was wrong. Even when we then tore the pistons out and showed them to them, they said they never saw anything like that and didn't know what would cause it.

Advertising isn't cheap, but I think these birds are gonna get some real cheap advertising...only not the kind I think they want!

jeepsr4ever

12-06-2006, 12:12 PM

I believe you should bring it back to them. Almost all machine shops will have various levels of experienced staff. You may have had a new guy working on your motor. I would bring it back to them and tell them how rare this engine actually is and that you have alot of time into the downtime on the motor and you need to have this done one time and right. I would also be strait forward without being to rude about it. They screwed up and they know it. Good thing is that they will fix their screw up :t:

As much as you want to tear their f@#$ing heads off. :(:

1980_Cj7

12-06-2006, 12:26 PM

Was just reading about the cam anti-walk kit in the sticky post on distributor gears. Would it be a good idea to install one on our re-rebuild?
300 broke-back miles? 8) Or is this a different cam 111!!! :idea: :-| :!: :t: 8) :?

Same cam, if we decide that grind will work for us. I was wondering if installing the anti-walk kit at this point might change the wear pattern that is already started.

1980_Cj7

12-06-2006, 12:31 PM

You may have had a new guy working on your motor.

Sad part is it was the OWNER himself, the one and same guy I've been talking to about the remedy, who assembled our engine! What does that say for the place???

And yes, we did tell him already that these engines are rare and it took us 3 years to find this one. Also told him that AMC recommended going no more than .025 over on the bores. We're already at .030 over and now have to go more.

The other thing we reminded him of is how terribly long it took him to get our engine done. He acknowledged that too.

jeepsr4ever

12-06-2006, 01:48 PM

I wouldnt quote AMC on the bore recomendation as many have run .060 over without issues. You should have him sonic check the bores so you can gurantee you wont need any block filler.

1980_Cj7

12-06-2006, 04:49 PM

I wouldnt quote AMC on the bore recomendation as many have run .060 over without issues. You should have him sonic check the bores so you can gurantee you wont need any block filler.

MC, can you please explain that so we can talk fairly intelligently about it when we approach him again?

Do most machine shops generally have the capability to do the sonic testing? What does it show, thin, weak spots?

How does the block filler work? Does it reinforce the weak areas? Wouldn't that mess up the cooling?

Excuse my ignorance on this and help educate me.

ironman_gq

12-06-2006, 11:18 PM

you usually only fill the block to the bottom of the core plugs. it helps keep the cylinders from distorting from heat and use and also helps to dampen vibration in the block. Overall it stabalizes the block and makes it stronger.

Mudrat

12-07-2006, 05:21 PM

DAMN!!! Not sure on the legal side. Did you just ask for your money back, (machining, labor and material) that you paid him?

1980_Cj7

12-10-2006, 04:31 PM

[quote="AMX69PHATTY"]
Here is the specs I fould for what I believe is your Clevite Cam
and the results of the SilvoLite Compression Calculator for your 401.
http://mywebpage.netscape.com/SketchKT/AMC+401+Ross+Pistons+Clevite+Cam+Info.jpg

OK you experts, in the specs above, what does the "Lobe C/L" mean? Our cam is No. 2 in the charts.

I'm trying to draw up a cam diagram, since we didn't get one with the cam. I have everything figured out and matching up, but that "Lobe C/L 110".

If it's the angle between the intake and exhaust lobe centerlines, I'm getting 140 degrees the way I'm calculating it.

Here's what I've come up with:
Intake opening 42* BTC
Intake closing 72* ABC
Intake centerline 105* ATC
Exhaust opening 82* BBC
Exhaust closing 32* ATC
Exhaust centerline 115* BTC
294* duration on both intake and exhaust
74* overlap
140* separation between lobe centerlines

Am I doing anything wrong?