Just for reference:
4776 1.25 1.312 1.5625 600 CFM
4777 1.25 1.312 1.6875 650 CFM
4778 1.312 1.375 1.6875 700 CFM
4779 1.375 1.375 1.6875 750 CFM
4780 1.375 1.4375 1.6875 800 CFM
4781 1.5625 1.5625 1.7500 850 CFM
From Holley catalog.
List Primary Venturi Secondary venturi Throttle bore CFM
What this means is RAMM's carb is a 750 main body with an 850 base plate. Probably flows better than 900 CFM easy at 20.4 inches.
