Eddy vs Holley CFM ratings?

Things are fussy in my mind, but Holley themselves rate (or used to rate) their own two barrel carbs differently than 4bbl. This means a 500CFM Holley 2bbl is something on the order of 350 when compared to a Holley 4bbl. 3" Hg vs 1.5 as I recall

I recall something about the Carters being rated "wet" meaning flowing fuel, or a likeness of fuel. I bet if you Google/ search this you can come up with a chart somewhere on the www

The other issue is vacuum secondary type considerations.

Holley of course has either vacuum secondary or "double pumper" full mechanical

Carter/ Ed has the old AFB style with the upper weighted door, or the newer AVS with a spring loaded upper flapper. These operate similar to either Thermoquad or GM Quadrajet, are adjustable, and make the carb operate more like a Holley vacuum secondary. That alone, makes a carb much more forgiving for sizing

Bear in mind that injection has none of these problems, because the fuel system does not need a "vacuum signal" nor does it need velocity through a booster venturi to make it operate properly