What RPM are you planning to run?

Cubic inches divided by 2, times RPM, divided by 1728 = Cubic feet per minute.

For instance, a 302 running at 4K RPM has a theoretical CFM of 305. In practice, the real CFM will be 85%-90% of the theoretical number due to intake and exhaust restrictions, failure of the cylinders to empty effectively on the exhaust stroke, etc. In real numbers, your 302 at 4K RPM will be flowing about 314 CFM.
Jerry

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