Who has the fastest /6 here
Well, I don't know what you would consider a "good breathing" head, but one such example would be the 302 Z-28 1969 Brand X stock head that was installed on that motor by the factory. It fed 39 cubic inches per cylinder (the same cylinder displacement as a 225 slant 6 has,) and because of the 4" bore, had room for 2.02" intake valves and 1.6" exhaust, STOCK. Ported versions of that head reportedly exceed 300 cfm flow rates for the intake (don't know the numbers for the exhaust,) and the numbers I have seen for a ported /6 head with the larger (1.75") intake valves, usually don't exceed 200 cfm, by much.
You can see the problem.
As I said before, the flow limitations are due to the small valves dictated by the bore size of the slant 6, and, I don't know how it would be possible to get around that, given that the bore center spacing is a part of the block.
If you know a way around that problem (other than forced induction,) I'd surely like to hear it.
Thanks for any info...
