[olddog]

Barry,

I wasn't using a carb sizing formula. I just converted cubic inches to cubic feet. A 4 cycle engine takes 2 revolutions to complete all 4 cycles, so multiply by 1/2 the rpm. This is what the pistons displace, on the intake stroke.

471 CI / 12^3 CI/CF * 6000 R/M / 2 R = 818 CFM

I do understand that it is possible to achieve more than 100% VE, using the momentum of the air to pack the cylinders.

I'm thinking, from what you explained, that the rating of a carb is at a certain manifold vacuum number, and the testing equipment wasn't the best. Therefore the rating of a carb and what will actually flow through it are not necessarily the same, especially in multi-carb applications. Am I understanding this correctly?

I have always wondered why certain engines had carbs that appeared to be way too big. The 340 Dodge Dusters with 3 two barrels, for instance. I suspected the factory put them there so you could install headers, port the heads, up the cam, and you were ready to go, without violating any racing rules. I had always assumed they would have made the same power with smaller carbs, but maybe not.

Anyway thanks for your time and sharing your knowledge.