[HeadDoctor]

Brian

Production cast iron heads are in the 130 to 150 cc range, if you want power in the 2500 to 6500 range then you have to stick with a 1.940 intake valve. I use 80% of the that area to decide how big to make the Int port at the P-Rod squeeze. We can make 400 to 450 hp with production iron heads, at a cost of about $2K. A good set of aluminum heads that will do the same thing will cost about the same money. Your biggest problem is that you have a carbureted engine, and can't take advantage of the "Long-Runner" EFI manifold, which will bring up the low end of the power curve. Along with that you could also get some extra long (40") headers, that would also help this low end torque problem in the 2500 to 6500 range - (See The Engine Masters Challange).

CFM @ 302 X 6500/3456=568
CFM @ 347 = 652.6
CFM @ 351 = 665.2

See - Now if you can find a Tunnel-Ram - mill off the carb flanges on the top and weld plates to it to cover the holes. then put 2 Mikuni-Weber or similar on either side of the plenum and wa-la you have a longer runner intake!!! As for the exhaust all you have to do is make some extensions for the primary tubes, get a new set of "Merged" collectors that fit the new diameter extensions and there you have it. This is not the ideal way to accomplish it but it will serve the purpose well enough. If the 2 side-draft carbs are too expensive then think about 1 55mm side draft.

Denny@JDS Induction Products