360 help

[MikeCJ7]

looking for some info or suggestions about 360s

I recently bought a 86 J20 for the engine and tranny to put into my 84 CJ7. Will probably go with a Edelbrock Performer intake, 600+ cfm carb, Hei distributor and not sure about cam and maybe pistons. I have been reading and reading posts for days and learning, but also getting confused. For a cam I was leaning towards a Summit 8600, but found a graph showing that the stock cam performing better. I sent an email to Isky cams for suggestions. I am running 4.88 gears with locker and posi and is not a daily driver. There are tons of trails here in AZ from easy to you will probably break something, I been out with guys that carry extra axles and on board welders. I would like to be able to do moderate trails, but also run higher rpms at the dunes, sand drags and maybe 1/8 mile Friday night drags. When I pull the engine and tear it down, if everything looks ok is it possible to install higher compression pistons without a lot of machine work? Like 343 pistons? I really like the 383 stroker idea, but do not have the funds for that right now, maybe in the future.

Thanks for any ideas or suggestions

Mike

[tufcj]

It's all in the gearing. In my 77 CJ7 I was running a 360. Bottom end bone stock, stock bore and pistons, stock 8.25 compression. Edelbrock Performer intake and Edelbrock cam/lifters. I had a 600CFM vacuum secondary Holley at first, then went to Howell EFI with a 590CFM throttle body. I spent most of my money getting the heads ported/polished/gasket matched, 3 angle valve cuts, bronze guides, hardened exhaust seats. I used early heads (either 090 or 993 castings) so I could run individual roller rockers. AMC engines like to breathe, so anything you can do to increase air flow really helps. Exhaust was stock free flow manifolds into 3" single exhaust with a high flow cat (I had to pass emissions). I had a T-18 w/6.32 first, a Scout Dana 300 t-case with a 2.62 low, and 4.88 gears, 37" Goodyear MT/Rs. Gearing was a little over 80:1 in low/low. Had custom Dana 44s in both ends with Detroit Lockers in both ends. It would idle with all 4 tires spinning if it couldn't find traction. I ran the Rubicon twice, and did the Dakota Territory Challenge 3 times without drive train breakage or mechanical failure (although I did roll it over at the Challenge). The engine would pull from idle to around 4500 RPM, pretty much done by 500 RPM. With a cast crank and rods, I think factory red line was 5500.

Don't go overboard with compression. Around 9:1 is the max I'd do on pump gas for a rock crawler. I'm not fond of the HEI units, I prefer a Mallory Unilite or stock MotorCraft with the large cap conversion.

Bob
tufcj

[MikeCJ7]

Thanks for the info Tufcj, good stuff to draw from. I am looking for a cam that will run in the moderately higher RPM range for the dunes, as long as I have torque close to what the 258 has. With 4.88s and 33" tires I have never been lacking for torque. It would seem silly when I pull the motor and have it on a stand not to at least install a new cam timing chain gears and the oil mod.

Thanks again

Mike

[tufcj]

I wouldn't do the valley oil mod unless you plan on having the block completely apart and tanked afterward. No matter how careful you are, some metal shavings will be missed. Go with either the smaller oil hole cam bearings or the smaller hole pushrods that Bulltear sells. I've got the cam bearings in my latest 390. I haven't run it yet, but it gets 60+ PSI with the priming tool.

Bob
tufcj

[MikeCJ7]

I'll keep that in mind,thanks

[MikeCJ7]

Edel Performer or Air gap with tbi, Summit 8600 cam and stock compression, maybe a little work on the heads ? I'm leaning to the Air gap for the simple reason it gets hot in the desert and it might help with the engine temps and running higher rpms during the cooler months at the dunes. Headers or get the better flowing driverside manifold? Suggestions?

Thx

[tufcj]

The performer and air gap are about the same performance wise, it would be your call. The only thing I've heard is some people have trouble with the air gap pulling oil thru the PCV. The 8600 cam will work well with stock compression. I also like the Edelbrock performer cam. Be sure to get the full kit and match the valve springs to the cam. The easiest way to ruin a cam is with too heavy valve springs. AMCs like to breathe, so anything you can do to the heads is a bonus (polish, port, gasket match). I've been very partial to shorty headers lately, look at the Patriot H8600. I understand they are exact repros of the long gone Edelbrock shorties.

Bob
tufcj

[MikeCJ7]

I bought a cam kit off ebay that appears to be same grind as k8600 for just over $300 because of some kind of a discount that looks promising. I've been waffling a lot on build plans and considering 2 options. I have the cam kit, Edel air gap, long tube hedders, transgo 2 shift kit for the 727. I was going to start with the msd atomic efi, but after more research it looks like a quadrajet is a good option for now and do the efi later, I just happen to have a freshly rebuilt marine qjet from 1 of my boats that lost one of it's engines. Jeep comes 1st, boat later. Option 1, ( if compression is good, and I believe it is ) Cam kit, oil pump and slow down the oil to valve train, intake, carb, hedders, shift kit and whatever little problems arise, get it into the CJ have fun this fall, winter, spring and save for 383 stroker bottom end to do next year orrr... option #2 go with 343 pistons now and not do the stroker. My big question is, what is the power difference between the 2???

This is the cam kit I got, http://www.ebay.com/itm/190865000400

[MikeCJ7]

Or option #3 try to find a 390 or 401 crank to offset grind. I have been looking, but not seen anything yet.

Also looking for recommendations for a machine shop in AZ that is good with AMC

[tufcj]

Unless you shave the tops of the 343 pistons, you'll end up somewhere around 11-12:1 compression. Way too much for pump gas and probably not great low end torque. A 390 or 401 will require notching the 360 block on the lower piston skirts for rod clearance. You'd spend about the same money for 360 pistons with 9:1 compression.

When I had my Jeep, I always built for dependability. It really sucks to break down on a trail somewhere. Sometimes the best parts aren't the fanciest.

Bob
tufcj