Cfm ratings / opening distance

[Marx3]

I have been wondering if any small cfm unit is capable of actually flowing 750 cfm, given a proper air flap opening distance?
Same goes for the large cfm units...
Will any large cfm unit actually flow those ~850 cfm, if the air flap and at what opening distance?
I know it is propably not as simple as that, but I suppose the opening distance of the air flaps will dictate the number of cfm the carb can flow at a maximum.

[Frank400]

http://cliffshighperformance.dreamhosters.com/simplemachinesforum/index.php?topic=2248.msg10510#msg10510

[qjetsrule]

I think the cfm can be calculated by a dyno or flow bench, but a lot depends on the motor. A strong motor will actually pull more cfm than a carbs rating and vice versa. As Cliff points out there are extremely fast cars in stock and superstock that must run the 750 cfm rated quadrajet. I'm sure the dyno shows more than 750 cfm going through those motors.