CFM Air-Flow Test
We took a Carter AFB from a 273/235 HP 'Commando' and flow-tested it
at the University of Binghamton {New York} Engineering Department.
Now, this AFB was 'advertised' at 500 CFM.
After some tweaking, and a little polishing of the throttle bore and venturi areas, we maxed out at 516 CFM's.
Primary ........ 1.437 x 1.063 x .7854 x 2 = 240 CFM
Secondary .... 1.563 x 1.125 x .7854 x 2 = 276 CFM
Net CFM's = 516