BT - to your questions:
(1) Don't know, we will NOT use the clones, so no answers for clones.
(2) Carter published 630 CFM
A lot of years ago, my Dad purchased a 26' Winnebago with a 454. Trying to keep a long story short here. We went to the Fall Hershey swap meet annually, and would set the speed control at the speed limit. The time to Hershey from Eldon, Missouri AS THE 454 CAME FROM THE FACTORY was 20 hours.
The power, and especially torque, with the spread-bore carb was not what I wanted.
I then acquired and Offenhauser intake for a square-bore carb; and 2 Carter AFB carbs, a 4760s (750 CFM) and a 9625s. I then "married" the 2 carbs. Used the 4760s as the base carb, and grafted on the automatic choke, choke linkage, and fast idle circuit from the 9625s. Calibration was left as stock on the 4760s. I also built and installed a cold air induction system (air is pretty warm under that doghouse).
That fall, we again made the pilgramage to Hershey, and again set the speed control at the speed limit. This year, and subsequent years, the time was 18 hours!!! The difference - speed we were able to obtain in the hills of Ohio and Pennsylvania. And the interesting statistic - fuel economy was IMPROVED by 8 percent.
Jon.
