I have a 1980 f250 4x4 with a c6 and a 460 right now i am running a stock 4 barrel carb on it but i just bought a new 460 40 over with a mild cam new intake and aluminum pistons. I dont think that the old carb will be able to feed my new motor so I need help figuring out what size to buy 600? 650? 700? Also if some one just new the formula i need to figure this out that would help to thank you .

 

Heres the formula from Holley's website
cubic in. X max. rpm / 3456 = cfm

Welcome to the forum.

 

well, i got a stock 460 and when you plug in 460 X 5500(max rpm) / 3456 = 732.(some change)

that would constitute the need for a 750 then, wouldnt it?

that's assuming i have an edelbrock performer intake, free flowing exhaust and headers

 

There chart will tell you what size to run. However that is only true in theory, because this is based on a engine running a 100 percent efficiency. I would guess your engine might be 80 percent efficient If your lucky, so a 600 cfm would give you more of the size carb that works with this formula. If your main objective is drivablity and reasonable fuel mileage with crisp throttle response go with the 600. The 750 will maybe gain you a little at the top rpm range of your engine, but it will suffer at lower rpms with less crispy throttle response and guaranteed lower fuel mileage. But to each his own. Tom

 

Yes, any 460 that can breath can benefit from a 750. A 600cfm is too small for this engine aside from a bone stock, fully smogged out unit. Even then its easily on the small side.