360 Cam Recomendation

[John N]

I've been reading thread after thread, trying to find something that comes close to my setup...no luck. Here's what I've got: it's a rebuild from a re-manufacturing operation, so it's on the low side for compression. I've been running it for 2 years and it's just plain weak for a 360. I have a Howell FI-tbi set-up on a Edlebrock Performer with a DUI ignition. The block is a more recent casting with '5.9L' on the sides. This is in a Jeep Scrambler with a TF999 automatic (stock converter); gears are 4.09 in Dana 44s with ARBs and 33" tires. My transfer case has a 4:1 gear reduction, if that makes any difference, for off-road. Off-idle is important.
So, if you've read this far....I want to try a cam change before I drop the bucks on a building another motor. This one has less than 10K miles and has decent oil pressure. I'm considering the Summit 8600, just not sure. Should I just change the cam and lifters or put more in it (pushrods, rockers, springs, retainers, etc...)?
Thanks in advance............

[jeepsr4ever]

8600 would be a good choice for this motor

[MIDNIGHT]

I have an Summit 8600 with lifters brand new in box for $70 shipped. Let me know

[sian09]

I have an Summit 8600 with lifters brand new in box for $70 shipped. Let me know

Midnight, I'm going to rebuild a 360. I'm interested! Do you still have it?
By the way, after reading more threads than I can remember one of them suggested to look for 360 info/buildups on this site, so I'm the new guy. So far so good!

[amcjeepman]

I am running a very similar set up in my CJ 7 trail Jeep. I think it is due to the late model heads. I have been told although not 100% sure that the later heads do not perform as well as earlier models. I have some heads from a '78 401 that I intend to try soon. Currently both of the late model( from the 80's) 360's that I have make nowhere near the power the '70s model 360s that I have owned and built for others. The 70's model 360's were not the high compression versions either.

[tufcj]

360 and 401 dog-leg heads have the same combustion chamber, port design, and valve size from mid 71 till end of production. 71-73 had GM style rockers, 74 up had the bridged rockers. The only different head is the 70 - early 71 (casting ending in 291-C) which had a smaller combustion chamber (but they need a little port work to flow as well as the 71 up).

You probably won't gain anything from a head swap. One important thing is to degree (and upgrade) the cam and use a performance chain and gears. Some of the later smog engines were built with the cam timing 4 degrees retarded for better emissions, it really hurt performance.

Bob
tufcj

[amcjeepman]

I have a newer style timing chain & gears w/ a Doug Herbert cam. I have done about 5 360s with this combination and the 80's versions both have less seat of the pants power in very similar applications. I always thought the heads were the same and still not sure they arn't , except for rockers and exhaust manifold//header bolts.
Several of us in this area that run/race AMC's have had similar results.
I have a hard time understanding/believing it myself but I've already done the cam/intake, timing chain/ gears, and fuel /ignition upgrades and still had the difference.

[eight]

As far as I can tell, TBI engines need cams with a low amount of valve overlap. The 8600 has 53 degrees which is about mid range for an amc cam. The crane 863904 has 42 degrees and is a 260/272 with .456/.484 lift. The comp 262H has 46 degrees and is a 262/270 with .493/.500 lift. According to DD2003 the comp 262H should be a great cam for a stock amc 360 with 502 heads and a 470 cfm throttle body. I've only got comp, crane, and summit cams in my database though. There are others that match the HP of the 262H, but those all have more overlap and less low end torque. And all the ones that have similar low end torque have less HP.

http://img.photobucket.com/albums/v160/ryankopecki/misc/comp262Hjpg.jpg

[John N]

Thanks Ryan, good information.

[bls33]

you might want to consider swapping in a more heavy duty tranny, or get kickdown linkage if you dont have it, the tf 999 isnt really the best tranny to have behind a 360, maybe consider swapping in a th400 or tf 727 depending on what t-case you have these could bolt right up

[John N]

you might want to consider swapping in a more heavy duty tranny, or get kickdown linkage if you dont have it, the tf 999 isnt really the best tranny to have behind a 360, maybe consider swapping in a th400 or tf 727 depending on what t-case you have these could bolt right up

I definitly have the throttle pressure linkage (aka kickdown), TF999 will burn up in a hurry without it. If they're built right, they can live behind some pretty healthty motors.

[amcjeepman]

I'm running a TF999 behing my healthy 401 CJ-7 for about 5 years now with no problems except twisted driveshafts on occasion.

[bls33]

dont mean to hijack, but hearing how your guys's 999's have held up makes me think about just keeping my tf99 in my CJ (swapping in a 360) it would save me alot of trouble...can you use a kickdown linkage kit meant for a tf727 on a 999?

[jeepsr4ever]

Yes you can...the 904's and 999's are (OK) tranny's but needs some massaging to handle big power. They can be built however...and built mean!

[John N]

dont mean to hijack, but hearing how your guys's 999's have held up makes me think about just keeping my tf99 in my CJ (swapping in a 360) it would save me alot of trouble...can you use a kickdown linkage kit meant for a tf727 on a 999?

Most of the time, TF727s cause a lot of front driveshaft clearance issues. Even if you clear it with 4" or more of lift, you will still be very tight. A built TF999 is much better, fit wise.

[KJMac]

Is the 999 shorter than the 727? How do they compare withe T-176?

Thanks

[AMX69PHATTY]

Back to the issue about the lack of power in the 360.
Have you re-curved the mechanical advance in the distibutor ? I have a steet . strip AMX and getting the distributor advance correct made a BIG difference. I removed the vacuum advance. My distributor is a Delco type. Bought a Mr. Gasket Kit. Installed the little Bushing that limits total mechanical advance to about 25 degrees and replaced wieghts and springs with Heavy weights and Light springs. Original parts pretty much NEVER allowed full Mechanical Advance. Old school drage racers completely lock out ALL Advance, and set Initial at 35 degrees. That is why they need a 20 degree start retard MSD Unit to get it to crank over and start. I didn't go this far cause it's a street car. The objective is about 10 degrees INITIAL Timing set by turning the distributor, 0 degrees mechanical advanced at IDLE, and 25 degrees of mechanical advance by 3500 rpm which with the 10 degrees initial is 35 degrees TOTAL advance at 3500 rpm. This really woke up the engine. Stock distibutors are not set up anything like this, especially smog motor ones. Used to be shops had ditributor machines they could put'em in and tune the advance curve. Fi you can find one that does that's the way to go. It's tough to get wieghts and springs set up to do it right.
This might be a cheap thing to try first.

10 degrees Initial Timing at Idle
0 degrees Mechanical at Idle
25 degrees Mechanical advance by 3500 rpm
35 degrees Total Timing at 3500 rpm
If you want Vacuum Advance, it has no impact on these requirements.

Also, make sure the Distibutor is properly PHASED.
That is at full mechanical advance, the Rotor Button TIP lines up directly with a Distributor Cap Post.
Theres a lot of pieces moving in different directions in the Distributor so how to set PHASING is hard to explain.
Weights move the BUtton, Vacuum moves the Switch Plate.
Let me know if you're interested in trying this and I'll take the time to go through it.

Sound like somethng worth trying to see if it'll wake up the motor ?
Don't know what it takes if it is a late model Autolite Distributor, never messed with'em.

Give it a shot.

[fuzz401]

3500 rpm when total comes in is a little late I think mine is at 2900

[KJMac]

My HEI is all in at 2900 also. I agree, 3500 is too late.

[John N]

I dropped in a DUI/HEI, pretty much, the way it came out of the box. It gave me about the same results as the MSD system. I did play with the curves on the MSD. I think my issues are low compression from a crappy rebuild and a stock or worse than stock cam.

[Holeshot]

Here's an experiment for ya:


Set your initial at 18 degrees.
Set your MSD (or whatever) to 20 degrees by 2500~3000.

It really gave my '70 390 a big seat-o-da-pants kick out of the hole and absolutely no cranking problems.

Low compression??? Have you tried adjusting the valves???

There are several different lengths of pushrods that came as stock AMC V8, maybe the valves are being held open??

Also, it's not unusual for high milers to have the pushrods popping through the rocker arms, meaning less lift & dur & power.

[Holeshot]

I was just looking at your Dyno2000 screen cap and one thing stood out like a sore thumb - 470 CFM!!!!

A stout 360 with standard hot rodding bolt-ons can use every bit of a Holley 850 Double Pumper (with a stick or loose converter).

That puny intake is good for maybe 3000 RPM.

Those heads need to breathe and are good for over 6000 RPM when fresh with a multi-angle valve job!!!

[eight]

The GM throttle body I use and Howell uses are only 470 cfm. Aftermarket ones can be had up to about 650 cfm. That and bigger injectors are in the plan for when I get around to engine mods. I'd like to get a 401 to start with, build it, then swap it in place of the 360.

[John N]

The GM throttle body I use and Howell uses are only 470 cfm. Aftermarket ones can be had up to about 650 cfm. That and bigger injectors are in the plan for when I get around to engine mods. I'd like to get a 401 to start with, build it, then swap it in place of the 360.
I'd like to start with a 401 too, but first I'd have to find a decent one to use.