I know what you're talkin about....but the difference won't be that drastic. Carter also used a similarly different method for measuring air flow for their carburetors than Holley. So....that means Holley used at least two different methods of measuring air flow. Honestly, the only way to determine what is what is to buy your own carburetor flow meters and measure and adjust them yourself. I used to have one years ago when I had a Triumph Spitfire with 2 SU carburetors on it. Almost a necessity with those and it certainly doesn't hurt in other applications.