AMC 360 built for torque ideas

[Saltwater Cowboy]

Alright, I am getting ready to rebuild my stock 360 in my CJ 7. I want this thing built for low end torque. My CJ has a NP 435/D300 Dana 60/14 bolt with 4.56 gears and 40" tires. I have had this motor for about a year now and it is starting to get weak. The Jeep is basically a trail rig and rarely sees pavement. We have everything up here in Alberta from mud to rocks, hills and sand. Should I just leave it stock and rebuild it or should I make some mods. Once again I am looking for low end torque so all those hp mods that move the power up in the RPM band is not what I am looking for. I am new to AMC motors but have learned a lot on this site. Thanks for any advice.

[ironman_gq]

bump up the compression, Get a good cam (Engle, or other good off-road cam) edelbrock performer intake good carb to go with intake. stick with stock exhaust manifolds, single 3" exhaust. That should just about do it. YOu shouldnt have to worry about oiling mods beyond small hole cam bearings or pushrods and makings sure your oil pump is in good shape/ midplate and gears for MC here or maybe one of his nickel plated covers.

[Saltwater Cowboy]

What cam would you suggest? I have a speed pro cam here that came out of another motor. It's specs are 204/214 dur. @ 0.050, 448/472 lift, and 110 deg lobe sep. Would this work? I also have a R4B intake, I know this intake jumps the power higher in the RPM range but would it hurt me more than help? Thanks again.

[msalaba]

In my 360, I run a Summit K8600 cam, Edelbrock performer intake, stock exhaust manifolds and stock bottom end. This setup had good low torque and ran strong to about 5500 RPM.

Desktop dyno gives this setup a flat torque curve from about 2000 - 4400 RPM and then drops like a rock.

I originally ran a Quadrajet carb and I really liked the vaccuum secondaries. I recently switched to propane and really like it in the off road. I added a MSD 6 box for propane as it requires a hotter spark. If yours is a tar baby, I'd stick with a carb.

[Saltwater Cowboy]

In my 360, I run a Summit K8600 cam, Edelbrock performer intake, stock exhaust manifolds and stock bottom end. This setup had good low torque and ran strong to about 5500 RPM.

Desktop dyno gives this setup a flat torque curve from about 2000 - 4400 RPM and then drops like a rock.

I originally ran a Quadrajet carb and I really liked the vaccuum secondaries. I recently switched to propane and really like it in the off road. I added a MSD 6 box for propane as it requires a hotter spark. If yours is a tar baby, I'd stick with a carb.

Did you do any other mods to the motor? i.e compresion ratio, heads. Thanks for the info

[JERSEYJOE]

First I would make sure the bottom end is sealed well. If you are just going to freshen it, hone the cylinders and use a moly ring. Shoot for 9:1 compression for regular pump gas. Find a set of early 50 cc heads. For the cam I like the Engle, not sure of the grind but it has like .501 lift and 212 at .050. Use a performer and a 670 truck avenger and hang on.

[ironman_gq]

I'm pretty sure the quadrajet has mechanical secondaries with an air door not vacuum secondaries.
I would look for a cam with 112 LSA rather thatn 110 that will widen the power band and give you more power under the curve which means you will make power earlier and keep the power up longer

[Saltwater Cowboy]

So would this be a good mix for what I am looking for? Stock rebuilt bottom end and heads, R4B intake, K8600 cam, mallory ign., and stock exaust manifolds. I do have a good Q-jet carb that I was thinking of using but if does not work out, I can always change it. I also have a set of fenderwell headers but I have been told for low end torque the stock manifolds would be better.

[tufcj]

+1 :?

I'm running a stock bottom end 1974 360 in my CJ. I just pulled the pistons, measured them and cylinder taper (all within limits). Honed and re-ringed, had the crank cut .010/.010. I dropped on the 1970 291-C casting heads to get compression around the 9:1 range. AMCs like to breathe, so I had the heads polished, ported, and gasket matched, and the exhaust valve sized to the later 1.68". With the early heads, I run roller rockers. Edelbrock performer cam and intake with Howell EFI. Stock exhaust manifolds to a 3" single exhaust. When I rock crawl, it will sit at idle and spin all 4 tires if it can't find traction. Overall gearing is a little over 70:1. It does fall pretty flat over 4500 RPM though.

Bob
tufcj

[Saltwater Cowboy]

I remember reading that you can use a chevy 400 piston in a AMC 360. Pros, cons? What mods do I have to do to use these? What kind of comp. will I get with these?

[ironman_gq]

I think you need to have the crank offset ground for chevy rods. and I think there was something to do with the compression height and valve reliefs on the pistons

[msalaba]

I'm pretty sure the quadrajet has mechanical secondaries with an air door not vacuum secondaries.
I would look for a cam with 112 LSA rather thatn 110 that will widen the power band and give you more power under the curve which means you will make power earlier and keep the power up longer

You are correct, the Quadrajet has a vacuum operated air door. This makes the carb effectively variable CFM to about 750CFM. I had better luck with this carb than my buddies running Edelbrocks with the off-road kit.

The biggest drawback to running a Qjet is finding a competent carb guy to tune it.

[msalaba]

In my 360, I run a Summit K8600 cam, Edelbrock performer intake, stock exhaust manifolds and stock bottom end. This setup had good low torque and ran strong to about 5500 RPM.

Desktop dyno gives this setup a flat torque curve from about 2000 - 4400 RPM and then drops like a rock.

I originally ran a Quadrajet carb and I really liked the vacuum secondaries. edit: mechanical secondaries w/ vacuum air valve I recently switched to propane and really like it in the off road. I added a MSD 6 box for propane as it requires a hotter spark. If yours is a tar baby, I'd stick with a carb.

Did you do any other mods to the motor? i.e compresion ratio, heads. Thanks for the info

Rotating assembly is stock. I recently had a pair of heads (later bridged rockers) gone through. (valve job) I had 0.045 shaved off for increased compression. This will better complement the propane I'm running.

Next year I will rebuild the bottom end if money allows. My goal is a C/R ~10.5:1 which works well with propane.

Desktop dyno gives my plan ~350 HP@5400 RPM and ~410 ft.lbs. @4400 RPM

[ironman_gq]

I'm pretty sure the quadrajet has mechanical secondaries with an air door not vacuum secondaries.
I would look for a cam with 112 LSA rather thatn 110 that will widen the power band and give you more power under the curve which means you will make power earlier and keep the power up longer

You are correct, the Quadrajet has a vacuum operated air door. This makes the carb effectively variable CFM to about 750CFM. I had better luck with this carb than my buddies running Edelbrocks with the off-road kit.

The biggest drawback to running a Qjet is finding a competent carb guy to tune it.

They are a pain to get tuned but they are probably one of the best carbs to come from the factory right up there and maybe even better than the motorcraft 2100. the small primaries make for great throttle response and they flow a lot of air (750 for car version 800 for truck version)

[offroadman83]

Anybody else have suggestions.......I am running propane with a amc 304. Its a complete dog so I have decided to switch it up with a 360. I will run propane on it too. Bump up the compression to help the propane. I will build it to be a torque monster hopefully as I have a 93 wrangler, with 1 tons (dana 60, 14 bolt) 5.38 gears and dana 300 tcase and 38.5" tires. Its a offroad only pretty much rig with an occasional street run.

[jeepsr4ever]

You can run flat tops or close forged pistons to bump it up quite a bit and a rv camshaft. We have the ability to offer virtually any compression for about $645 shipped with H13 tool steel pins.

[offroadman83]

thats probably what I will do then. I was planning to build a motor slowly anyways-----------Kyle

[msalaba]

I got a pair of bridge rocker heads rebuilt this spring. New valves and a grind. Had him mill 0.045" off to bump comp. (put me close to 9:1 iirc) Got them bolted on before memorial day.

What a difference in torque running propane. The engine will lug 500 RPM easily. Didn't do that before.

The only downside to the comp bump is my starter does not like it. And it's only 3 years old!

Can you say gear reduction starter?