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.
Carter #4294S
Primary ....... 1.437" {1 7/16"} ....... Venturi .. 1.063"
Secondary ... 1.563" {1 11/16"} ...... Venturi .. 1.250"
Now, this AFB was 'advertised' at 500 CFM.
And depending on what articles you read, these AFB's were rated at
anywhere from 470 to 525 CFM's.
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 .743 x 2 = 227 CFM
Secondary .... 1.563 x 1.250 x .743 x 2 = 289 CFM
Net CFM's = 516
