New Heads?

[frozen]

Hey guys

I am planning on doing the old rebuild pretty soon. To minimize the down time I found a 360 block out of an old 80's FSJ. I have a 72 360.

I was under the impression that the compression was higher with the old 360's.

If that is the case can I rebuild the newer (80's) engine and swap it in or do I have to rebuild the old engine?

Thanks for the help

-Pete

[Torque]

You can use the block from the '80.When you get new pistons you can specify the compression you want.There are some good articles in the tech library.Also the machineshop thats going to do the boring ect. should have all sorts of catologs to go through.I guess you have to decide wether to stay totally stock,mild upgrade or beyond.If you let us know if this is a daily driver or a weekend toy there are far more qualified people to make some excellent suggestions and pitfalls to avoid

[frozen]

Thanks Torque

The Beast is not a daily driver, though I don't do any wild off roading with it. I do tow boats/trailers etc with it. It is more of a work horse/camping rig/bad weather beast. Any information or recommendations would be very welcome.

Thanks again

[Serious Johnson]

Froze:

Here's the sum total of what I think I know about AMC heads. The later "dog-leg" exhaust ports flow much better than earlier square ports. The switchover was sometime around the end of the 60s or beginning of the 70s, at about which time chamber volumes and valve sizes increased. So is there a small chamber, big valve, dogleg head? I have no idea. I'll be following this thread as I'm about ready to refresh my '83 360, and would love to know whether there's a better performance head choice before dumping time & money into the ones I have.

:-

[Al Johnson]

Originally posted by Serious Johnson:
Froze:

Here's the sum total of what I think I know about AMC heads. The later "dog-leg" exhaust ports flow much better than earlier square ports. The switchover was sometime around the end of the 60s or beginning of the 70s, at about which time chamber volumes and valve sizes increased. So is there a small chamber, big valve, dogleg head? I have no idea. I'll be following this thread as I'm about ready to refresh my '83 360, and would love to know whether there's a better performance head choice before dumping time & money into the ones I have.

:-The general consensus is that the dogleg head is hard to beat. I'm not sure about the specifics, but seems to me I've heard of a couple different combustion chamber sizes in the dogleg head variety. Maybe more info on froadin.com or http://pub8.ezboard.com/bamcforum.
Al

[bvibert]

Here is a list of the different AMC heads that I found on the net somewhere:

http://www.fullsizejeeps.com/jeeps/files/bvibert/amc-v8-heads.jpeg

Sorry its sideways...

[Josh D]

All 360 use dogleg heads. Only early '71 (first year of 360) used a dogleg head with 52 cc chambers and adjustable rockers. Late '71 through '91 use dogleg, 58 cc chambers and bridged rockers, so there would be no benefit to using your '72's over the '80's heads. The earlier 290-343-390 AMC's are the motors that use the pre-dogleg exhaust port heads with smaller cumbustion chambers. As far as uping compression ratio with pistons, think expensive. You can use 343 replacement pistons to up the compression on a 58 cc headed 360 for about a 10:1-10.5:1. Too high for most applications. Its possible to get about a 9:1 ratio by machining the block for zero deck height and shaving about .030 off the head and using off the shelf 8.5:1 360 replacement pistons. This may or may not effect the intake to head mating relationship, so additional machine work may be required there as well. The only other route is custom pistons, which get expensive. I think plenty of power can be had from the 360, because the heads flow so well, that the stock 8.5:1 compression ratio is fine. Just choose a cam thats good for building good cylinder pressure. Plus, you can run a little more advanced timing with the 8.5:1 under load on pump gas than a higher compression ratio, which is important with the heavy weight of an FSJ. Jump on some AMC, AMX, and Javelin boards and see what those guys are building as well, just keep in mind they are building for e.t.'s in lighter cars. Let us know how it goes.

[Torque]

www.cfsja.org/tech/building.htlm (http://www.cfsja.org/tech/building.htlm)

[Torque]

sorry try
www.cfsj.org (http://www.cfsj.org) then check out tech articles

[Torque]

www.cfsja.org (http://www.cfsja.org)
its been a long day

[frozen]

Lots of good info guys. The article at cfsja.org recomended that a SB chevy and a TH400 case be swapped in instead of rebuilding the 360.

Any thoughts?

Priorities are
1. Cost
2. Reliability
3. Performance

Thanks for the help

[mdill]

Based on your prioritys

Priorities are
1. Cost
2. Reliability
3. Performance

1) The 350 swap will cost more, less for the engine , a lot more in misc cost
mounts, electrical, exhaust, radiator, swap trany to a chevy pattern case ..
2) If done right either should provide long service, give the edge to the AMC
not because of the engine just all the above that has to be done will not
have been done in a stock mannor and I would expect more opps I should
have done .... another way with any swap.
3) Performance conflicts with 1) , If you want EFI, better heads, wider selection
of low cost performance parts, hands down the chev engine can be built
at lower cost than a AMC, the question does the level of performance you
are after make the AMC cost high enough to over come the cost of the swap ?

Good luck with her.

Mike D.