Need information on AMC 360-401 Iron heads

Old Rugged Crosser

April 12 2010 < I wish everyone would do that! Hi Guys, My project is a full caged 72 CJ-5 with a 360. I fabbed a new 2x4 frame and a quarter elliptic rear suspension of my own design incorporating a rotating cross-member to keep the drive angle alignment during articulation, using a narrowed Ford-Lincoln 9" rear end with disk brakes to go along with the Ford truck disk brakes on the front, keeping the 5 1/2" bolt pattern front and rear. It can go through 2' of drop and maintain drive line angle without binding the ujoints! Braking is by a hydro-boost unit. I junked the 3 speed manual tranny and installed a AMC TH400 and mated the old Dana 20 twin-stick transfer case with Advance Adapters tranny-xfer case adapter , both having been refreshed. Drive lines yet to be made. The motor supposedly had been rebuilt 30K ago. I took a compression check on it before I pulled it and it was 150# across the board. I don't know if this is good or bad for this motor, but I decided to go with it. I just installed an new cam and a Bulltear roller timing set. The cam is a Comp Cams High Energy hydraulic AB XE274H10: valve lift: .520/.523 duration: @ .050 .230/236 on a lobe separation of 110.0 I was looking for a low rpm torque cam. I also bought Bulltear's reduced oil push rods, as I hear that oiling might be a problem on this motor. I don't want all the oil sitting on top of the heads. I am using a Edel RPM Air Gap intake with a 650 Edel carb. I replaced the front cover and oil pump with a new Bulltear unit. Am using a Mallory HEI for spark. The gear ratios are 4.56 using 33's with a Detroit locker in the rear and a lok rite up front in the Dana 30 which is SOA on Tuff Country Waggy springs with Teflon. I did a shackle reversal and while I was at it, also changed to a high steer setup using Reed flat top knuckles with Ford spindles and rotors from Parts Mike, another good guy in California. I changed the locking hubs to Warn premium 19 spline D44 hubs. The front axles are beefy Chevorlet 4x4 using 297X ujoints. Spring control is by Billstein. Using parts on hand I installed a Bronco 36 gallon fuel tank which feeds a Fram gas filter and on to a blue Holly electric fuel pump. The line is a SS braided hose which makes a stop at a fuel pressure regulator before hits the carb. The Headman Headers feed the Flowmaster 44's on out the back via 2 1/2" pipes. By the way the paint is going to be AMC blue/white/red. That will go over my new Smitty-built 6"tube flat fenders and 3" rear flairs, which I welded to the full corner guard blank body armor on the rear, all from Gen-Right. I used the blanks so I could center the wheel openings since I slid my rear wheels back a couple inches due to the extra length of the TH400. I still need to purchase my seats to put on my gray Hurculiner covered floor. While I had the tub off the frame I went ahead and sandblasted the underside and undercoated and painted it with some silver-gray paint to sit on Eastwood's satin extreme chassis black frame. Now, seeing that this is my first experience with AMC, having said all that, my question is: If I were to stay with iron heads what head should I look for with the best valves and proper quench chambers. I am a good head porter so that is no problem. I just want to start with the proper head and not waste my time on inferior heads. Could you please give me the proper nomenclature and tell me what they would have come in so I will know where to look. This will be next winters project. I hope to spend this summer wheeeelen and enjoy my retirement out in nature. If I say so myself "not to bad an accomplishment for being 65 with both knees having been replaced twice and 2 new hips to go along with the ss cage that was built around my spine to keep it straight and not really out of pain. Thank God for the meds to keep this old hulk going! In the middle of this project I had to stop and have some bone replaced in my left hand which became infected with accute staff infection and just about lost my life over that, but God was merciful and had his hand on me and gave me another chance at life. The Doc's said it was real close. Also, one more question, what kind of timing do these motors like? Also I need to replace my harmonic balancer. Any suggestions without going to the high $$ high revving drag stuff? My pockets are just about empty. I do enjoy your forum that you have hear. I really enjoy all the info that is spread around and for free. =D> But, sometimes we all know what that is worth. Keep up the good forum. :sa: Old Rugged Crosser :(: :(:

ironman_gq

The early heads have smaller chambers and offer higher compression but have rectangular exhaust ports and dont flow as well. The later and more common heads have dog-leg exhaust ports and larger chambers but flow pretty well as they are. AMC's like to breath so if you are going to spend time and money in the heads spend it on a good valve job. For a low end torque motor nothing more than a gasket match should be needed on the ports just so you dont have any edges catching the airflow. I think a lot of guys end up using Chevy valves but I dont know the specifics on all that. Someone will surely chime in before to long that will know a lot more than me.

Old Rugged Crosser

After posting my rant I discovered that some kind soul had posted a chart on head nomenclature. I decided to go and look to see what heads I presently have on my 360 and to my pleasant surprise I discovered that I have the 291-C heads with the 50 cc chambers. So the head problem is solved for me. These are the heads that I will clean up next winter. Wouldn't You say? I wonder where that puts my compression ratio assuming that the pistons are stock? Old Rugged Crosser

tufcj

Stock compression with the 72-up heads is 8.25:1. The 291-C heads will give you somewhere between 8.75 and 9:1. There are specific porting instructions for the 291-c heads. It may be posted here, or you can find it in the book "Performance, American Style" on eBay. I run a set on my 360 powered CJ, and on my 390 powered 69 AMX. Both sets have been done with 3 angle valve jobs, ported, polished, gasket matched. They all have 2.025" exhausts, early 291-C heads have 1.62" intakes, later ones are 1.68". That makes the valves slightly bigger than the Chevy "fuelie" heads.

msalaba

tufcj wrote
They all have 2.025" intake, early 291-C heads have 1.62" exhaust, later ones are 1.68".

Help ya out here... Long day? :razz:

tufcj

:(: :(: :(: :(: :(: Kept getting interrupted during my reply, totally lost my train of thought (short train) :roll: :roll: :roll: . Thanks for straightening that out. Bob tufcj

Old Rugged Crosser

Well guys as luck would have it the subject of heads and valves came up. As I said above that I went out to see what heads I have on my 360 and this brought my attention to my heads. Upon closer inspection I discovered that 3 valves in one head and 4 in the other head were just about to pull through the retainer locks. It was to the point that the rockers were going to push on the spring retainers as the valve stems were just about to disappear. That would have been the end of my good heads and a bunch of pistons! I would have been doing this: :smile: :smile: :smile: big time! Needless to say I ordered a new set of springs and retainers from Comp Cams. I am getting the Beehive spring set with the variable spring tension. Now I need to buy a complete set of valves. Have any suggestions there? Also this would be a good time to get that 3 way valve job you recommended. I also need a new harmonic balancer. Any ideas there? After reading some of the posts you talked me into ordering one of those nifty alternator brackets that Bulltear makes. I just wish he made one for the steering pump. By the way, is that who the "MC" is that I hear you refer to quite often? Old Rugged Crosser :sa:

tufcj

MC = jeepsr4ever = owner of Bulltear.

On the 291 heads on my CJ, I just used stock replacement valves. On my AMX, I have stainless valves with 4 groove retainers since it sees higher spring pressure and RPMs.

I bought a lot of stuff from Mad Dog www.hdmaddog.com when I was building the AMX.

msalaba

In my experience, bring your heads to a competent engine shop. I had my heads gone through and found out the springs Summit recommended for their K8600 cam were too light. I have the late 360 bridged rocker heads. The seats were good, but the valves were shot. He sourced some new valves that had the 4 groove retainers, which were the same as stock. Also got the correct springs and he shimmed them for the proper seat pressure. Had a 3 angle valve job and shaved the head. (Running propane so I had a wider contact width on the exhaust valves and shaved the heads as much as possible ~0.045" iirc) Cost me ~$700

Old Rugged Crosser

tufcj wrote
MC = jeepsr4ever = owner of Bulltear.

I bought a lot of stuff from Mad Dog www.hdmaddog.com when I was building the AMX.

MC How do you feel about the quality of their parts, such as, Valves, pistons, rings, and such. Especially their diamond turned pistons? The prices seem to be real good.

fifesjeep

I would purchase the smaller stem Chevy SS valves and have the shop machine the valve guides to fit them, this will lighten up your valvetrain and help reduce the chances of floating valves at higher rpms. Toss some roller rockers on their and you'll be in there. :t:

Mudrat

Lotta stuff going on here, I love it :t:

TufCJ and FifesJeep are both gearhead mechanics and good at what they do. If you’re going to push the speed limit, the SS valves and rollers will work well for that application. If you’re just going to the red line occasionally, put the money into a 3* valve job and port and polish the heads - you'll get more 'bang for your buck' than rollers (Harmon, Crane, Comp ... ) and with the 8600 or 8601, your red line is still over 5grand on the tach. What axle ratio are you going with? Where are you building engine performance at? [Has a lot to do with the rest of the trucks performance.]

I've got the Summit cam, but went with msalaba's option on the professional build on them from a local race shop. They measured valves, spring matched the weights and provided the correct length push rods to meet the rod-angle geometry in my 360 heads using the OEM style rockers. The little bit of friction (HP) saved with rollers wasn't in my requirement$ $heet :?:

I'm also running some Mad Dog Racing parts and haven't had any worries with the double roller timing setup. Got Bulltear's nickle case cover and oil pump setup along with the matched cam gears and spiffy ALT relocation bracket.

And I too would like to see the PS relocation idea hit the street, but I bought the BT serpentine setup, just haven't had a chance to install it yet (Rich, when you coming over?? :-| ). And I still have a set of nitride coated headers that have been under my desk at work for a year or so!! Guess when I get the slush box rebuilt and ready to install, I'll change my headers too 111!!!

Anyway, I just got back from 3 months in Japan and have a full list of 'gotta do first' items (that's the 'honey do' list we all dread) - including about 10 cords of wood that needs split and off my yard!!! :shock:

A total quality product requires a comprehensive idea on what the end-product should look and act like. Building a 10K RPM capable motor is spendy and wasteful unless you're going for 8's or 9's in the 1/4. If you’re looking at a capable wheeler and DD, the engine needs to work with the axles and tire diameters to operate in a suitable and efficient (road) or power (off-road) RPM range. Unless it's a purpose built machine, there will be compromises, and only you know what you can afford - both in $$$ and capability.

There are a slew of RPM vs Speed calculators on the web.

Or if math hurts your head like it does mine, check the chart <HERE> :?

In my CJ, @ 2650 (+/-) RPM, w/4.56 lockers and 35's, I'm pushing 63-65 MPH by GPS. So the chart is close at 2625 RPM and 60 MPH. :mrgreen:

'Rat

msalaba

Old Rugged Crosser wrote
Now, seeing that this is my first experience with AMC, having said all that, my question is: If I were to stay with iron heads what head should I look for with the best valves and proper quench chambers. I am a good head porter so that is no problem.

Also, one more question, what kind of timing do these motors like? Also I need to replace my harmonic balancer. Any suggestions without going to the high $$ high revving drag stuff? My pockets are just about empty.

Old Rugged Crosser 🙁: 🙁:

Seems like you got the head question sorted out. Just get 'em rebuilt.

Harmonics balancer -> http://www.damperdoctor.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=DD&Category_Code=AMC
I don't know if anyone has any experience with them or not. Found them in a forum.

Leave the timing factory unless you plan on a trip to the dyno. You have a pretty mild build so factory would be close.

You really should not have to go crazy with your Jeep. The 360 in my CJ5 is stock 78 block & rotating assembly w/ rebuilt 85 heads (late bridged rocker) Summit K8600 cam (214/224 @0.050") Edelbrock performer intake (#2131) MSD 6AL ignition w/ Motorcraft dizzy running on propane & stock CJ manifolds. Screams right up to 5500 RPM w/ plenty of torque down low. I think the most cost effective way to get more power out of this rig would be to get a 401. I just don't think I need it.... Yet...