Does anyone know a formula that can be used to figure the CFM of a carb bore? The Ed that works for me wants to know the CFM for an Autolite carb. It is a 2 bbl carb and each bore is 1.14". A 4 bbl Autolite sqaure bore with 1.08" bores has a CFM of 480, so eac... Login to read more.