The volumetric efficiency of that engine is no where close to 100 percent (unless you have upped the compression to maybe 11:1, and had a custom-ground cam installed). More like 75~80 percent.

Thus the equation for needed CFM at W.O.T. would be:

CFM = [(302 * 3500 * 0.8)] / 1728

CFM = 489 maximum

I ran a Carter 400 CFM on a modern 300 CID with 9:1 compression and headers (no cam change) and it was just about right.

It could be your carb needs more tuning, it also could be the timing curve.


Jon.

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