Rochester Carburetor Flow Ratings

Rochester Carburetor flow ratings cfm 4-bbl Quadrajet: Air flow at 90o air-valve opening 1-3/32-in. venturi (primary) 750 1-7/32-in. venturi (primary) 800 Dualjet 1-3/32-in. venturi 227 1-7/32-in. venturi 287 Varajet (staged 2-barrel) 28mm primary 375 30mm primary 397 Model 2G: 1-1/4-in. flange, 1-7/16-in. throttle bore, 1-3/32-in. venturi 278 Model 2G: 1-1/2-in. flange, 1-11/16-in. throttle bore, 1-3/16-in. venturi 352 1-1/4-in. venturi 381 1-5/16-in. venturi 423 1-3/8-in. venturi 435 Model 4G: Throttle bore & venturi size in inches 1-7/16 – 1-1/8 primary; 1-7/16 – 1-1/4 secondary 486 1-7/16 – 1-1/8 primary; 1-11/16 – 1-15/32 secondary 553 1-9/16 – 1-1/8 primary; 1-11/16 – 1-15/32 secondary 692 Monojet 1-7/16-in. throttle bore, 1-7/32-in. venturi 160 1-11/16-in. throttle bore, 1-5/16-in. venturi 210 1-11/16-in. throttle bore, 1-1/2-in. venturi 250 NOTE: 4-barrels rated at 1.5-in.Hg pressure drop 2-barrels rated at 3.0-in.Hg pressure drop 1-barrels rated at 3.0-in.Hg pressure drop