Two-barrel vs. Four-barrel CFM Ratings

Not only are Holley 2bbls rated different than Holley 4bbls, but Carter used to rate theirs different from Holley

I believe Carter were rated "wet" which was supposed to be more realistic

Holley 4bls (I believe) are rated at 1.5Hg" vacuum drop where 2bbls are rated a 3" Probably had to do, at the time, with accuracy of testing equipment