Desk top Dyno

[KJMac]

Could somebody DD my engine with this Isky Cam Please?

Stock 360 with performer manifold 750 carb, headers.

open close

Int 32 68 .490 LSA 108

Exh. 68 32 .490

Thank You

KJ

[KJMac]

O C

The timing at .050 is Int. 4 40
Exh. 40 4

Thank YOU!!!!

[Holeshot]

Hi.

I have a stock '70 (prepped w/3-angle valve job & minor cleanup 291C heads) already modeled in D2K (using '70 390 cam specs), it was 10~1 compression, I will drop it to 8.5 for your engine (the '70 I have is 283HP@5500 & 287ft/lbs Tq@4500).

I will assume that you will be using "small tube headers with mufflers".

Here's your cam:
Isky 280-HL
High Perf. Use.
Lopey idle.
2500 Stall.
3.70-4.11 axle ratio.
Up to 750 CFM Carb.
9.5:1 compr.
RPM-Range (2500-6500)
Valve Lift (.490 .490) Valve Lash hot(.000 .000)
ADV. Duration (280 280)
.05 Duration (224 224) LC 108

There's really no "boost" for a Performer intake, it's just a small-runner dual plane, like a stock 4bbl intake.

A single-plane (Torker) will add around 25HP & 12 lbs Tq., while shifting the powerband up slightly.


http://home.comcast.net/~dhoelcher/amc/tech/eng/kjmac1_sm.jpg

With a single-plane intake...

http://home.comcast.net/~dhoelcher/amc/tech/eng/kjmac2_sm.jpg

With 10~1 compression...

http://home.comcast.net/~dhoelcher/amc/tech/eng/kjmac3_sm.jpg

There is about another 100HP you can get with a few more mods and a more radical cam, raising the redline to between 6800 & 7500.

The head modeling used here was chosen because it closely aproximates the power levels of the stock early seventies AM V8s.

Sorry if I missed anything.

Here's the head flow data...

/////////////////////////////////////
// BEGIN "70_stk.flw"
// 1970 AMC 291C flow file
3.10
Stock 291c 2.025/1.68 Factored to 462HP
0
8
1 2.0250000
1 28.000000
1 0.200000
1 0.300000
1 0.400000
1 0.500000
1 0.600000
1 0.700000
1 0.800000
1 0.900000
1 118.000000
1 167.000000
1 203.000000
1 225.000000
1 225.000000
1 225.000000
1 225.000000
1 225.000000
1 1.680000
1 28.000000
1 0.200000
1 0.300000
1 0.400000
1 0.500000
1 0.600000
1 0.700000
1 0.800000
1 0.900000
1 100.000000
1 129.000000
1 146.000000
1 155.000000
1 155.000000
1 155.000000
1 155.000000
1 155.000000
// END FILE
/////////////////////////////////////

[KJMac]

Thank You, That was great information!!
I'm thinking that cam is a little big for my Jeep? I use it for hunting too.

Thank You!

[1980_Cj7]

Holeshot, you seem to be really good with Desk Top Dyno. Would you mind running our new 401 build for us? We tried, but there are a lot of factors we were just guessing at, like the head flow. Here's what we have:

401, .030 over
Ross forged pistons which are supposed to give 9.8 to 1 with the 58 cc heads
Stock 6090 heads, decked enough to clean up
Clevite 284/284 hydraulic cam, 218/218@.050, .488/.488 lift, 105/115 lobe separation, operating range 2000-4000
Hydraulic lifters
Stock individual stud rockers
Edelbrock Performer intake
Edelbrock Performer 750 CFM carb, choke removed
Stock electronic distributor with TFI adaptor, cap and rotor
TFI coil
Stock cast iron exhaust manifolds (the free flowing design with center dump driver's side and rear dump passenger side
2 1/2" pipes crossed over into a dual inlet glass pack muffler
Single 3" pipe out the back from muffler

If you need anything else that I might have missed, let me know. Thanks.

[Holeshot]

Hello.

Before I run the software, be so kind as to describe exactly what you want out of the engine, specifically, the never to exceed redline you would like to rev to, and intended use of the vehicle.

Willing to put in a "looser" torque converter? (727s can use smaller displacement engines converters, like a 360 converter in a 401, measure their diameter & use the small one. Also, MOPAR 727 converters will work with AM727s, smaller means looser).

Like I tell everyone, the "dogleg" heads flow EXTREMELY WELL (much better than most of the competitions "good" parts) & if you use small intakes, carbs, & cams, you are choking the engine down out of it's intended power range. I am a FIRM believer in enhancing the great AM head design and complimenting it by using low restriction intake, cam, & exhaust systems. Using any "Performer" parts is little better than stock and makes me a little sick :roll:

My main pc is down & it has all the data, I am heading out to BestBuy for pieces & hope to have the network up 2nite, stay tuned....Dave

[1980_Cj7]

The engine is in an 80 CJ7 that is driven on the street, and used offroad, mainly on big rocks. It has a 727 behind it, and a Dana 300 with 4 to 1 and 32 spline outputs. Don't recall the stall speed, but when the torque converter was replaced way back when we were running a 258, there were 3 available, stock, lower, and higher stall speeds. We went with the higher one.

Axles are 4.10 Dana 60's with Detroits. 38.5x14.5x16.5 SS TSL's.

As far as redline, don't really care, and won't exceed. Want lots of low end torque mainly for the rocks. Was hoping the 9.8-10 to 1 compression ratio would work with pump gas, but finding it wants LOTS of base timing and more than 94 octane.

Fuzz keeps trying to talk us into an air gap intake instead of the Performer, but we were thinking the Performer would work better at low end. Were also planning on going with either a Holley Truck Avenger 770 CFM carb or TBI later down the road.

Our research had told us the 401's liked bigger cams, so we tried to go big enuff there.

[1980_Cj7]

Oh yeah, and we have an electric fan (radiator).

[Holeshot]

Sorry, my new Asus motherboard is locking up with the WinXP "blue screen of death" & I haven't been able to run anything on it yet.

You have a rock crawler/street vehicle & you want low end torque. Low end torque is highest with small ports & valves because that keeps the velocity up. The "dogleg" heads are large port, large valve, great flowing heads that flow well at the higher rpm levels. So putting a small runner intake like a Performer, a small carb, etc., is taking performance away, instead of optimizing the rest of the engine to match the capabilities of the heads. A MUCH better choice would be the Edelbrock R4B or a "Machine" intake, both of which come up on Ebay for $300~$400, and are worth the small extra amount as they are only increasing in value (discontinued decades ago), instead of decreasing, as the performer & air gaps are (still in production). More performance is available with the Torker, which shifts the powerband up a little.

Like you said, the 401 likes cam, it wants to breathe, the Performer intake & carbs are stock level performance parts, not able to supply the heads with the flow needed. An R4b & a 3310 750 vacuum secondary should be considered the minimum needed for a stout 401, not sure what your cam specs are, but even the '71 401 cam needs that much intake to be in tune with the heads. An 800 to 950 Holley is needed when more performance potential is built into the engine with porting, biger valves, more cam, headers, etc.

The AM V8s are actually quite tolerant of compression, 10-11~1 is possible without race gas but the misunderstood concept is that the piston to head clearance must be .045" in order to AVOID detonation. Let that clearance get too big (common) and the engine will detonate and the CR will drop. A common head mod is to "open chamber" the heads, which will increase the chamber volume, and then mill them to get the .045" clearance. While having the heads worked, a porting job and 2.08/1.74 valves installed as described in the 70s "Performance: American Style" handbook can add 100~150 horsepower at 6500 rpm or so, while making the engine more efficient and actually reducing the detonation possibilities.

<MORE later>

[1980_Cj7]

Man, our new engine has so much power it blew up your computer! Hope you had a scatter shield around your hard drive, ha, ha.

The only thing I have on the cam is: Clevite 284/284 hydraulic cam, 218/218@.050, .488/.488 lift, 105/115 lobe separation, operating range 2000-4000


We'll definitely stay tuned and are anxiously awaiting more suggestions.

[Holeshot]

That cam is barely above stock.

Fresh heads are good to 6500, so I try to push people towards a cam that starts pulling at 2500 or so, with 6500 as the redline. You may lose a little bit of torque below 2000, but when you have over 500 ft/lbs from 3500 to 6000 and 585 horsepower at 6500, whatever was lost at 2000 rpm means little (to me). This 401 build is with fully ported BCI heads & big valves (2.14/1.9), a solid .629" lift cam, Torker & 850 carb, big-tube open headers. It really costs very little more than a mild build, between + $1,000 and $2,000 if you have Indy do the heads.

A virus ate my old motherboard and Asus has a problem with their integrated audio on this "A8N-VM-CSM" piece-O-crap!!!!

[1980_Cj7]

But remember, we want low end torque at idle and just above for what we are doing. We need a fairly smooth dependable idle too. 6500, or even 3500 don't work here, we need slow and steady.

https://home.comcast.net/~rwsr50/ComcastOnlineStorage/Rousch070505_007.jpg

[Holeshot]

just what the 199, 196, & 232 six-cylinders were made for!!! Not a fan of the 258 six.

[1980_Cj7]

But remember, there's no replacement for displacement. And like I said, we do run it on the street too, and can't wait to surprise some ricers, like ol' Fuzz does.

[AMX69PHATTY]

Howdy HoleShot, don't mean to hijack but .......
what you were saying about heads, flow, detonation, and .045 clearance.....

Two things,

1) The 360 Ross Pistons that Maddog FastEngineParts are offering,
they claim 10.2:1 Compression and I get 9.65:1 when I do the calculations.
Have you checked to see what you get ?
The Ross Piston Specs are 1.596 Compression Hieght, 21cc dish volume,
58cc Heads, 4.11 Bore, 3.44 Stoke, 9.208 Deck Hieght.
If I use 9.173 Deck Hieght, deck milled .015, I get 10.0:1.
Have you ran calcs on those pistons and got the 10.2:1 like they claim ?
Was just wonderin' if my calculations were wrong.
See the jpeg image of my Compression Calculation Spreadsheet in my other thread
Pistons .010 above Deck - Opinions

2) You've probably seen my other posts. I'm rebulding the motor for my '69 AMX.
It's a 343 Block. I've cheated and used a 304/360 crank offset ground .010 for 3.46 Stroke.
Stock 5.875 Rods, and cast Pistons 1.581 Comp Ht with a 27cc dish.
Pistons stick out of the block .011, .035 clearance with the Heads.
Heads are milled .060, mildly ported, 48cc, 2.02 / 1.68 valves Stn Stl 11/32 Stem.
What I've been fightin' is to get 10.2:1 with these dished cast pistons.
Cam is .512/.529 280/295 at .005, 106 Intake Centerline.
Holley 850 DP, Torker, 1-5/8 Headers, 2-1/2 exhaust, Auto, 3000 Stall, 3.73 Gear.
Think this will be good for 500 HP ?
I've read the thread here about quench and shock waves, and detonation.
Seems I'm on the right track from what that says.
Now if I can only figure out how to get .100 Piston to Valve Clearance.
Right now I've only got about .075,
thinking of having the piston valve reliefs machined a little deeper.
Any Comments, opinions, suggestions ?

thanks HoleShot, hope ya get yer PC up and reunnin' soon.

[Holeshot]

Ross pistons from MD - they are generic smallblock chevy clones with improperly positioned valve reliefs. I bought a set from them & ended up giving them to my machinist in trade for labor. If you buy them directly from Ross, you can get them with the correct valve reliefs to match the AM combustion chambers, which will yield the advertised compression. I bought the 13~1 ones which end up around 11~1 with "open chambered" & ported combustion chambers.

343 - You will HAVE to use thicker head gaskets, the .045" figure is the minimum needed to keep the pistons from smacking the heads, .040" being the ABSOLUTE minimum. Why do you have the pistons sticking out so far??

If I was to use cast, KB are the only ones I would consider, & limit the rpm to 6500 bursts.

The only way I would ever want to use dished pistons would be for a turbo, flattops are the way to go for anything else. If you use flattops with the reliefs in the correct position you can then remove more material at the reliefs if you need to lower the compression.

Why are you using cast rods, crank, & pistons? Getting HP out of the smaller engines usually means pushing on to higher rpms. The 390 & 401 cranks & rods can be used in the smaller blocks. Custom pistons with the larger pin bores will be needed. You can also use aftermarket H-beam SBC rods either modded for the big pins & thinner thickness at the journal or pistons with the SBC pin size.

500 HP?? probably between 400~450

What ya need are Ross pistons like the Fuzz pistons below, I think they are only in the five-hundred something range, Fuzz???

[fuzz401]

my Ross flat top piston
http://img.photobucket.com/albums/v31/fuzzcj7/Picture015.jpg

[AMX69PHATTY]

Cost is the reason for the combination I'm trying to assemble.
Motor was together, had only 9.0:1, 325HP@tire w/TF727, 12.60@109mph, 6000 shift.
After many years, I lost self control, held it to 7000, spun #5 Rod Bearing.
So I'm trying to rebuild with similiar parts with 10.2:1 cost effectively.
Spun Bearing ended up cracking a lip off a piston, discontinued Sealed Power Cast #9047P.
Got a set of identical Zoellner pistons from MadDog for $88 + shipping !
Reground the 304/360 Crank offset .010 to increase compression to 10.2.
Without the .010 offset, had 0.000 deck clearance & 9.0:1, ran for 10+ years.
Was trying to re-assemble the way it was, just with higher compression without spending buku bucks.
Forged Pistons = $700 - $800 - Zoellner Casts = $100.
Only spinning motor to 6000-6500, if I maintain self control (rev limiter).
So maybe I'll just have to get another 304/360 Crank Kit stock 3.44 stroke.
This will give a 0.000 deck clearance and 9.0:1 compression like it was.
Or have .010 milled off the perimeter lip of the pistons and increase valve reliefs by .03 to .05.
Motor ran great but I beat it and broke it, and trying to fix it without spending big bucks.
Using casts parts to keep down costs.
Pistons stick out .010 trying to get 10.2 with that 27cc dish.
Torker intake already machined to match heads with .045 Head Gaskets,
but does someone make thicker AMC Head Gaskets ?
Thanks for you input. Discussion helps a great deal.
http://mywebpage.netscape.com/SketchKT/AMC+AMX+365+Bad+Piston.jpg

[Holeshot]

Cost is the reason for the combination I'm trying to assemble.

You should be learning by now that the cost of breaking & rebuilding is quickly outpacing the cost of doing it right once!!!

I am pretty much against trick combinations that take specially machined parts (Smokey Yunnick fan here). Off the shelf is cheaper & easier to duplicate if the need arises.

I still say get a 390/401 crank & rods plus FORGED flattop pistons (rods & pistons are the areas that AMC-ers may break the "off the shelf" rule when stroking & substituting other mfgrs parts).

The early 390 rods are 5.79" long and the 401 rods are 5.858" long, both are good to 8000 rpm after beam smoothing, resizing, and shot-peening.

You had such a narrow piston to head clearance, I am surprised it didn't fail sooner. Probably either smooshed some carbon or other debris or hit the head after the rod clearance opened up enough to let the piston reach the head at high revs, I guess. An AM engine should be able to run 6000 all day long, if the oiling system (& pistons/rods/crank) is up to it.

A well done 390/401 should last 30 years between major OH if ya feed it clean air & oil plus maintain it with a set of bearings, rings & valve job & VALVE SPRINGS (every year or two, maybe more if over-revved) when needed. That would be as a hobby car, not a daily driver or race car.

I hope I haven't misled anyone, this is what I believe to be true. I think the AM design is the best of the 60s & 70s, I don't pay too much attention to the computerized smoggers that are all but impossible for the normal person to work on.

[youdidwhat]

Nice looking rig :idea:

[AMX69PHATTY]

Yeah it worked a long time only running it to 6000 rpm. :?
What broke it was winding it out to 7000 in 1st & 2nd during the 3rd 1/4 mile pass in a row back to back.
There were very few people at the track that night, no line to wait in to make a pass.
It spun #5 rod bearing one half over the other that night, but didn't break the piston.
It wasn't knocking except here and there at idle when hot, so I knew sumthin was wrong.
Later, after about 2 more months of street driving, one night getting on the interstate,
the Rod had finally offset ground the crank enough to let the piston hit the head and bang bang bang bang bang.
I drove it about 7 miles that way even, and made it home to the garage.
Damage was the broken piston pictured and three bent valves from piston pieces.
Should have gotten over the denial and dis-assembled it before breaking the piston.
Poor judgement on my part.
111!!!
So your right, it handled 6000 rpm for a long time, even without the extra oil line,
just not 7000 rpm in 1st & 2nd, heat soaked, 3rd pass in a row #-o