Carter Carburetors ~ Advertised CFM Ratings and Corrected CFM Flow Ratings ~

69 Cuda 440 said
We took a Carter AFB from a 273/235 HP 'Commando' and flow-tested it
at the University of Binghamton {New York} Engineering Department.

Do you recall the pressure drop and set up?
Pressure drop is, of course, a critical variable, but entry and exit will influence the cfm as well. I'd think with a carb bolted to the bench, exit is less important but an air cleaner base or stack on the top could make a measurable difference.

67Dart273 said
Just like cams or any other rating, it would be great if they were standardized so you can accurately compare 'em.

The OEM's write the specifications to meet their own needs and the suppliers have to meet those specs. Granted there usually is negotiation and equivalents can and do get worked out. Setting standards is often done within an industry and there probably was little incentive at the time for either the auto makers or the carb manufacturers. I suspect that when flow ratings were published for the public it was because that carb was being sold aftermarket, or the car's marketing called for it.

"Some automobile manufacturers rate Holley carbs at other pressure drops, giving different flow ratings than Holley's specification. Example: Chrysler rates the 2210 two-barrel at 2.0-in.Hg pressure drop at WOT and uses a reduced cfm rating.
"Holley standardized flow rates at 1.5-in.Hg pressure drop for three- and four-barrel carburetors; 3.0 in.Hg for one- and two-barrel carburetors."

from Mike Urich & Bill Fisher Holley Carburetors & Manifolds (HP Books) revised edition 1978 p.81
Note: This book carries the bias and authority of Urich being VP of engineering at Holley and the book is Holley p/n 36-73