Building an AMC for torque

[derf]

I saw the HorsepowerTV show this last weekend where they built up an AMC 360 and it got me thinking. Sure, it made good power up high but that's pointless for real world driving.

I've got a 360 out of an 84 Wagoneer that really should be rebuilt. I want to put it in my 86 J10 and get some really great torque from off idle to a usable 4K+ RPM.

I don't want to say I have an unlimited budget but I've got more than enough room in the budget to build the engine the right way. I can have the machining done that needs to be done and can afford to do the things that are nice to do but not absolutely mandatory. I can do aftermarket heads and what not, but I don't necessarily want to throw money at the build just to say I threw money at it. I really only want to buy the parts that make sense to install to reach my power goals.

So if you were going to build a torquey 360, what would you do?

The engine probably has something like a 8.25:1 compression ratio or close to that. How much higher would you want the compression ratio to be? I don't want to have to run premium so I don't want to bump it too high.

What about heads? Is there any reason not to run factory heads? I know I don't need the port/polish job because I won't really go much over 5K RPM. But do aftermarket heads offer something for the power goal I'm targeting?

Is there a better manifold than the Edelbrock Performer for this kind of build?

What about the camshaft? What kind of profile is best for torque in the idle-5K range?

How much real difference do roller rockers make? Are they worth it for a street engine like I'm building?

What else would you do to the engine if you were building it?

[tufcj]

Welcome to Bulltear!

Factory compression is 8.25. If you're replacing pistons, I'd bump it to around 9:1.

Stock heads are probably best, but AMC engines like to breathe, so polish/port is not wasted money. Have a quality 3 or 5 angle valve job done.

The performer or if you can find one, the R4B, are probably the best manifolds for off idle performance.

Camshaft, something in the .475-.500 lift range with a shorter duration, something in the 270-280 range.

Roller rockers do free up some horsepower, and help with valve guide life. Not terrible expensive. If you currently have bridged rockers you will need to have the bosses machined and add guide plates.

Fuel injection is wonderful, a Howell TBI works great, and a free flow exhaust, 2 1/2 w/H-pipe or x-pipe for duals, or 3" single.

That said. My 360 Jeep CJ was running a bone stock bottom end. I had 1970 heads (291C casting) that had been ported and polished, 3 angle cut (this gave me about 9:1 with stock pistons). I was running an Edelbrock Performer package, (cam, lifters, manifold), dual roller timing chain, roller rockers. Howell TBI and factory manifolds to a 3" single exhaust. With the 80:1 low/low gearing, 37" tires, and Detroits in both axles, I could sit at idle and spin all 4 tires while rock climbing.

Bob
tufcj

[jeepsr4ever]

Bump the compression and install a RV cam with a 600CFM edelbrock carb (with offroad needles and seats). You dont need to open up the heads for the RPM your hitting you will loose velocity. Bob is spot on and remember he is talking about advertised duration not just purely intake or purely exhaust duration. You definately want at least a performer intake. Bob those 291 heads need a port job to flow what a bridged rocker head flows (just a mild one).

Your only going to gain power by increasing compression. You do this with a RV cam and a mild bump in static compression by better pistons and end up with a higher dynamic from your camshaft's ABDC which on a lower end cam is much faster. Also getting your piston to the top of the deck makes a huge difference and tightening up that quench area is HUGE (from zero deck pistons)

[Lenni AMC]

9,5 - 9,8 compression
Crane H-272-2 cam
Rhoads style lifters
Edelbrock Performer intake
Headers
Good port job on heads
MSD orHei Distributor
Recondition Rods or go H-beam
Roller rockers are good investment
Comp Cams Hi tech pushrod these will not bend or brake trust me
Edelbrock or Holley carb 750 CFM AMC engines like big Carbs and good flowing heads
K&N filter

And then just make shure you got the right glue to hold the axles together when you pull something

This combo has worked very well for me but algso this combo will get you power all the way to 6000 rpm
maybe you could go a little less cam but I think sometime people go overboard when choosing a tourqe cam a milder cam than orginal will NOT give you a fun engine


Best Regards from Iceland

[derf]

So people throw out the "RV cam" but what does that really mean? I know. It makes good low end torque. So for a low end torque motor I need a low end torque cam. Great.

What makes it an "RV cam"? What should I look for in the duration and the difference between intake and exhaust duration? What about lift makes it an RV cam? What lobe separation angle?

Also, I can tell you from experience that an Edelbrock with the "off road kit" stinks of road. If I was going to stick with a carb, it would be with a Holley Truck Avenger. That carb will run just fine off road. I know. I've owned and driven both. But for this build I'm going with throttle body fuel injection.

[jeepsr4ever]

If you dont bend the floats down the offroad needle set will stink. If it is setup properly it does pretty darn good offroad. The term RV cam comes from actual recreational vehicles (camper) where the torque needs to develop from idle due to the weight of the vehicle.

[derf]

Yes, I know the derivation of the name.

I'm asking about technical specifications that make it an "RV" cam. Does anyone know what makes a cam an "RV" cam?

[jeepsr4ever]

IIRC it has everything to do with the lobe seperation.

[tufcj]

Lobe separation angle has a lot to do with torque. The Edelbrock performer is at 112 degrees, and makes good torque in my 360 right off idle. The cam in my AMX 390 is 108 degrees, makes good HP, but really doesn't start to pull until I'm over 2500 RPM.

Keep the LSA in the 110-112 range for a good off idle torque and throttle response. You probably also want to keep the carb in the 600-650 range, vacuum secondaries, for the best throttle response. The throttle body on my 360 was only rated 590, and I never had a problem with it running out of steam until it was over 6000 RPM, and how often do you run an engine built for off road torque at that RPM?

I've found AMC engines really like split lift/split duration cams. My AMX is running a .512/.525 lift, 284/290 duration cam. Crower makes most of their AMC cams this way, and I like them.

Bob
tufcj

[fastr@pahrump]

All of the above, just bore it out .060 over(check cylinder wall thickness,some blocks can be bored out more) for more displacement. Aluminumn Heads will let you run more compression 10.00-10.25 easy, Edelbrocks not Indy!, port size is similar to stock( velocity), and your performer intake will fit better, and cheaper!