J.H. - now why in the world would you want to compare everything the same way??? That would make things way too easy.
Actually, one and two barrel carbs were always rated at 3 inches Hg, beginning back in the '20's and '30's. This seemed to be a good average representation of the vacuum of these engines at WOT.
When four barrel carbs came into being, it was found 1 1/2 inches Hg more closely represented the average vacuum at WOT. To convert the 3 inch Hg to the 1 1/2 inch Hg scale, divide the 3 inch scale rating by the the square root of 2 (1.414).
Then in the 1960's one manufacturer started rating carburetors "dry" (air only), vs "wet" (air and liquid mixture). There is about an 8 percent difference in these ratings (a 500 "wet" actually flows about 40 more CFM than a 500 "dry").
I am not sure anyone really understands :confused: the ratings of the last few years, other than they flow markedly different than the same castings did ten years ago. It must be the new math :mad:
Jon.
