amc 360 shim head gasket 0.020 thickness

morehops

Hi Bulltear folks,

Does anyone have a good source for this? I found one option here: http://www.innomach.com/images/2012-IMS-CATALOG.pdf

at $35/per head, but don't know anything about the shop. Does anyone here have a recommendation?

The machine shop was able to machine the head to get 8.5:1 compression and he said if we can get a thinner head gasket, we can maximize quench to get 9:1 compression. Will be running a k8600 on a full engine rebuild. Only keeping the stock pistons with an engine hone and new rings. Crank was turned 10-10. All new clevite bearings. Will be running performer manifold with an edelbrock 600.

Thanks!

Shawn

tufcj

Reading the link you posted, I believe those shims are to be used WITH a head gasket, NOT instead of one. A Fel-Pro gasket is only .045" thick when properly torqued, so you'd only gain about .025". McCord used to make steel head gaskets for AMC. I used them in a few of the race motors I built. They're a BEAR to get to seal, the best being on a freshly decked block with freshly surfaced heads.

AMC heads from about 74 forward gave about 8.25 compression with stock pistons. How much was shaved from the heads? Once you get past about .020" combined from the block and heads, you have to start worrying about manifold fit and pushrod length. You could go to 1970 heads (291-C casting), which had smaller combustion chambers. Cometic makes AMC head gaskets down to .027" but they're expensive (over $100 a set).

http://www.shopengineparts.com/parts.aspx?eid=977&cid=40&type=engine&vtype=Domestic+Auto&make=AMC&model=360+V8+70-91

Bob
tufcj

morehops

Bob, thanks so much for the quick response! You are right in saying that I won't gain much, but from what I understand even a little compression bump will help with a more aggressive cam. Both surfaces will be fresh, which should help seal. Since this is a weekender I'm looking more for reliability. Would you think the shim would be less reliable? My goal is to keep costs down and still get some good performance. I don't think I'm paying more than $300 at the machine shop and $200 in parts. I do not want to deal with fitment issues on the manifold. Shawn

tufcj

What cam are you planning on running? More isn't always better. You need to match your cam to compression, intake/carb, exhaust, gearing, transmission, and running RPM range. I had a very mild cam in my Jeep. It didn't have a lumpy idle or sound tough it ran out of steam above 5000 RPM, but it would pull stumps at idle. In my AMX I have a fairly aggressive cam, but still not huge (.512/.525 lift, 282/292 duration). It ran a best of 13.57 @ 102 with full exhaust and street tires a couple of weeks ago. It's still street friendly, I drive and cruise with it all the time. Bob tufcj

morehops

Bob, I'm running the Summit k8600 lift is .497 and duration 224 at 0.050. t176 4 speed, I believe the gears are 3.73. Edelbrock intake, 1406 carb (600cfm) I figure this is an around town cj7, not looking for high RPM, just a fun engine with good power and some good sound. No definitive exhaust plans yet... I like to hear some good sound from cam, exhaust without annoying other folks on the road.

morehops

Also, with the price of the cometic being so high, we are just going to deck the block and use the standard head gasket.

tufcj

That's a good cam for a 360. Do check the fit of the intake manifold and length of the push rods as you assemble the engine. Cams are a huge compromise, nothing out there will do everything (short of the new electronic stuff). For more bottom end torque, you lose top end HP. For more HP, you lose low end torque. My 77 Jeep was running the Edelbrock Performer cam and intake, it had was a bone stock bottom end, 72 heads (individual rockers) that had been polished/ported/gasket matched. Stock exhaust manifolds into a 3" single exhaust (to meet emissions laws). T-18 trans, Dana 300, and 4.27 gears. I was running 37" Goodyear MT/Rs. It would pull very well from idle on the trails, and still drive decently on the street. Bob tufcj

morehops

Thanks Bob that's great to hear. The machinist is doing a full valve job on the heads with upgraded springs, so I expect it to be a strong engine. Any suggestions on exhaust? NC doesn't have much to say about exhaust except that its is bolted on somehow.

tufcj

The AMC free flow manifolds flow about 90% of what a header does. (All v-8s used them from 71-up). Outlets on the free flows are 2.25", I'd go up to 2.5" if you're running dual exhaust, if single go 3". If you go with headers, Patriot exhaust makes shorties, or go with inside the frame rail full length headers. I'm not a big fan of fenderwell headers on Jeeps. The fenderwell headers leave the mufflers exposed and prone to damage. Bob tufcj