Best Head for IMCA Hobby Stock

[Dirt Track Dodge]

imca rules say.....
CYLINDER HEADS: Steel only. Must be unaltered approved OEM and minimum 76 cc combustion chamber. Chrysler - no after market or W-2 heads, 360 cubic inch heads only. No porting, polishing or alterations of any kind to heads or intake

[JVMopar]

Well they left that door open. Magnum heads. Or if you don't wanna run the magnums then 308's.

[Dirt Track Dodge]

chambers to small?
cast iron intake to fit bolt angle?

[lt]

you're going to be shy of the 76cc chamber minimum with most any production head so I wouldn't worry about that. 308's sound like a plan.

[JVMopar]

Just wallow the holes out in the intake to fit it to the magnum heads. Or you could have them drilled for LA bolt pattern.

None of the chrysler small block heads are that large. The 76cc rule is for GM heads as they had a ton of heads with different cc's.

[chrisII]

so, why is the 308 better than the X head? Ive got a set of X heads , should i sell them and pick up a set of 308s? (I run an asphalt sportsman 4412 .520 lift magnum exhaust with 2 1/4 mandrel bent 2 into 1

[JVMopar]

The 308's are supposed to flow just as good if not better, PLUS they are 20 years newer and more abundant and cheap. And Magnum heads flow better than that. Or so they say. I haven't done the actual flow tests but this is the general concensus.

There has been alot of talk about small block heads in the performance section.

Here is a site that has alot of flow numbers for different heads. http://users.erols.com/srweiss/tablehdc.htm

From their site at .500" lift intake/exhaust flow
308- 209/147
J (2.02-1.60)- 200/140
"340's standard @ .600"- 189/142
Magnum- 212/146 and at 0.700" 215/147

The site is kinda hard to follow as things aren't labled very well so you gotta take eveything with a grain of salt.

[moparracer54]

i honestly feel that with the little turd 2" exhaust that imca make's u run that any production 360 head will be fine........JMO

[chrisII]

so, what I have heard in the past is that the X flows slightly better than the J. others say they are the same. either way, with a 4412 I don't believe there should be much difference. If i Didn't already have the X heads i would go 308, but might as well keep what i have? sorry for the hijack, seemed to somewhat relate.. 2" exhaust? omg IMCA does have some silly rules. limiting an engine with exhaust is a bad idea. it just makes the heat build up and is bad for the engine.

[B-Mod Dad]

To run Magnum heads you will have to run dish pistons to stay under the required 9:1 comp. rule. We run flat tops with "J" heads and a thick stock head gasket and need to have piston down in the block about .020 to get to 9:1. Even then you need heads and block that haven't been decked very much. We have never found a head over 73 cc's.

[340king]

I just looked at a good reference for stock head flow. It is:

http://users.erols.com/srweiss/tablehdc.htm#Chrysler

From this you can see after some getting used to the posting format that they all flow about the same on the intake. Where the 308's and Magnums shine is on the exhaust, getting much closer to the desired 75% flow rate.

With those rules, the bowtie boys have a huge advantage if they can run Vortec heads. They flow in the 230's properly prepped. You can't get there with any stock small block heads legally. You will be hard pressed to get much past 215 cfm.

The chart shows one guy reporting 215 and 220 cfm from Magnum heads. I never have seen that kind of output on any heads we have flowed. We were mired in the 205 cfm range. We did do some legal work on the 308's and got them up to 215.

It all comes down to the castings. If you have 20 sets of heads to pick through and flow test, you could end up with a great pair. The odds of picking up that one lucky set are pretty slim.

[ebody#11]

Does anyone make a good stock appearing iron open chambered head for the small blocks. We run b-mods and use a stock J- head now with the 1.88 valves. Just looking to make an improvement, or is there something we can do to the J- head to give us a little more.