Frank, try this site from Holley, they are the performance carburator people
CFM calculator I read somewhere,maybe on Inliner's, the larger Model B Rochester flows about 150 CFM, I don't know if that's factored like a 4bbl or if the information is accurate. Fred makes a good point, carb adapters can cause restricitions or fuel metering problems.I saw a 261 powered 47 Chevy car with 3 Holley Webers, ran very well.Maybe that's what Fred's friend needs for his engine.
