My first AMC 360

Saltwater Cowboy

Alright, I know this has been asked a 1000 times but I am gonna ask it 1 more time. I am about to start my first ever AMC engine build up and I need to know what I am gonna get out of it. I have a 83 CJ 7 with a D60/14 bolt axles, 4" springs, SOA, 40" boggers and 4.56 gears. It will be used as a trail only ride with the odd outing to the beer store. We get all different terrain up here so it needs to have good bootom end torque but still be able to spim those tires in the mud. I am bolting a NP435 between the 360 and D 300. I don't want to get crazy with this thing so if I don't have to do any machine work I am not going to. I am thinking on a good rebuild, aluminum intake, cam, fenderwell headers, and a good 4 barrell carb. What kinda numbers can I expect from this thing and what other mods do you guys recomend. Thanks in advance.

jeepsr4ever

I think torque numbers are going to be alot more important with those gears and that tire size than horsepower. You will want to develope 400ft lbs of torque around 2500rpm to start to clean out those boggers. Boggers by weight are almost twice as heavy as TSLs of the same size. (mere specualtion based on carrying both the heavy bastards in a 44" tire) You are running a 435-d300-4.56 combo. Your 435 hoprefully you have the 6.68-1 ratio this would give you a 80.4 crawl ratio (pretty good! you will feel any power adder to that stock motor at this point) or if you have the GM/Chrysler steeped down 435 you will have a 4.56-1 ratio so your crawl ratio will be 54.8 (In this case you will want some more low end) I dont think its critical that you build the baddest low end motor ever if you wheeling in low range but it could be a tremendous help. I think the basics would be fine. Rebuild with a aftermarket intake, bump in compression and a nice low end camshaft.

runnamuck

i would stick with factory exh. manifolds. supposed better torque numbers, plus they won't get smashed like fenderwell headers. why not lower gears? heck i'm running 4.56s w/ 36s and 465/300.

fifesjeep

With those big tires You should be running 5.13's.... Your crawl ratio will be less than 80.4... Due to those big-ass tires... I have 42" Super Swampers on my 82CJ... (I'm in the same boat). The lower you keep the Jeep to the Ground (Suspension/tires etc) you'll have better stability and you'll notice the Gears more... Just have good flex with good clearances, ie: tire to frame/tire to tub...ground to bottom of axle pinion etc... Are you LOA or are you still under?... I'd go with a performer intake and a Holley truck avenger carb... 600 to 670cfm... A stout RV cam (Look around compare cam specs to other manufacturers... and then make your decision)... I have Dynomax Fenderwell headers and I'm thinking about switching to the stock headers just so the rocks don't bash them... Along with the 3" Purple Hornies...

Saltwater Cowboy

I don't want or need lower gears because I am getting the crawl ratio I need from the 6.68-1 first gear. I still need wheel speed in the mud and I pull around 2500 rpm on the highway so the gears work good (sometimes it can be a little bit of a hike between trails). OK the normal bolt on stuff I understand but the bump in comp., how, I keep hearing about how difficult and pricy it is for pistons for a 360. Can I just shave the heads? I will be going with a Truck Avenger or get a 4 bbl motorcraft. Will the 670 truck avenger be to much? oh and yes I am soa. Thanks again guys.

jeepsr4ever

You can take .025 off your heads to gain around .5 in compression. No a 670cfm shouldnt be too much for your 360

fifesjeep

You may have a 6.68 1st gear ratio, 4:1 t-case (Or what-ever you have) and 4.56 gears... BUT with those larger tires it Drops the Crawl Ratio! :idea: If you want I'll post the Formula to figure it out... Along with how much to mill off of the heads in-order to get the CR that you desire... But, In-order to get the most out of the Gearing you want to stay as low (Tire Size) with the maximum amount of under clearance and Awesome flex to compensate for being low... (With being low to the ground and having great flex, the benefits will by far out-way the negatives).
I have a set of 42" Swampers that I'll be selling when I get back to Va.... They have 3/4" to 7/8" of tread still on them... They have some rock rash etc... but the 15X10 8 lug rims go with it... $450.. They're heavy as shit... I'm dropping down to 38's... with 16.5" rims. When I get back to Va I'll post some pics on the For Sale Page.

Saltwater Cowboy

I would love to know exactly how much I can mill off of the heads. I already have the formula for figuring crawl ratio so I don't need that one. We have much different conditions up here to wheel in and wheel speed is very important. Which is why I need the gearing I have. I may be jumping up to 44 Boggers and if I do I will change to the 5.13 gears. Quick little question if I keep the stock bottom end, do a std. rebuild on the heads, stock exaust manifolds, alum intake, and a mild cam, what kind of power numbers will I be looking at?

82Waggy

200-250HP

fifesjeep

Shit, I forgot the other formulas in my room... I'll repost later with the formulas for milling the heads for desired CC & CR...
I do have at the moment...
Gear Ratio = RPM x TIRE DIAMETER / MPH x 336

EFFECTIVE DRIVE RATIO
Effective Ratio = Old Tire Dia / New Tire Dia x Original Ratio

EQUIVALENT DRIVE RATIO
Equivalent Ratio = New Tire Dia / Old Tire Dia x Original Ratio

Alright here is the formula etc....

AMOUNT TO MILL = New Disp. Ratio Minus Old Disp. Ratio Divided by New Disp. Ratio Multiply Old Disp. Ratio...... Once you get that number Mulitply that by the Stroke.
If you know your current specs then you should be able to apply this very easily to your heads etc.. You could also "0" deck the block etc...

NDR - ODR
NDP x ODR
Then x by the stroke

AMX69PHATTY

Understanding is the Intake Valve Seat is the limiting factor to head milling. Seems to me that the max mill is around .080, but I'm not sure. Mill them enough, and eventually it will start breaking into the Intake valve seat. I have some '70 heads that were milled .055, and the edge of the intake valve itself is slightly below the finished gasket surface of the head. Also if heads and block are milled, then the intake manifold must also be machined to maintain port alignment.