Thread: What to do

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The cam that's in the motor is very well matched to the static compression ratio, 224 degrees intake duration, 9.6:1 SCR. If you opt for more cam, which will extend the intake closing point, you'll need to raise the SCR to match. For instance, moving from your 224 degrees of intake duration, up to 230 degrees of intake duration, will require a minimum of 10.0:1 SCR. Moving up to 236 degrees intake duration will require a minimum of 10.5:1 SCR. Moving up in cam timing without raising the static compression ratio will result in the motor being a pooch on the bottom and mid-range. There is no free lunch. You might be able to use a little more cam due to the cylinder packing and subsequent cylinder pressure improvement of using the AFR heads, but I'd be conservative here. Call up your favorite cam grinder and talk with a savvy tech guy. Matter of fact, call several cam grinders.
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I'd opt for the AFR 290 heads and back the whole mess up with a 10", 3000 stall converter. Use Fel-Pro 1047 or AFR 6849 head gaskets. Weiand Stealth #8019 would be my choice of intake manifolds. Edelbrock does not make a BBC high-rise, dual-plane configuration except the Air Gap, which I consider a redheaded stepchild, more targeted at marketing B.S. than performance. Reports of poor performance (poor throttle response) in cooler climes has convinced me that you don't need an open type intake manifold on a street rod. You need the heat of the motor to help turn the liquid fuel into vapor for good throttle response. You may be thinking of using a single plane intake manifold, but for the rpm range of the ZZ502 cam, 1500-5500, you will find that the motor will make more power under curve with a tall dual-plane like the 8019.

Now, the thing that I would be most interested in doing is to insure against detonation on pump gas by tightening up the squish/quench to between 0.035" and 0.045". This would require complete disassembly of the motor to cut the block decks to zero deck, with the thickness of the head gasket being the squish/quench figure.
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You can't use a steel shim gasket to get there, the heads won't cooperate. They will fret with a solid gasket. You need a composition gasket that will give a little.
I know you have no intention of doing this, but think about the increased cylinder pressure from the increased flow of the air/fuel mixture into the motor through those far-superior AFR heads. I would either cut for zero deck or be thinkin' about some water injection. Of course, I'd keep a close eye on the plugs for signs of detonation before I'd do the water.

CFM Intake flow comparison ZZ502.../...AFR290...DIFFERENCE...PERCENTAGE OF DIFFERENCE
0.200".......138.......163.......25.......18%
0.300".......193.......235.......42.......22%
0.400".......233.......289.......56.......24%
0.500".......272.......330.......58.......21%
0.600".......299.......360.......61.......20%
0.700".......318.......375.......57.......18%

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