My quadrajet came from a 71 455, carb #7041540. I thought 71's were 800 cfm, but the guy who rebuilt it insists that it's a 750cfm. Is there a surefire way to determine what's what?
A 7041540 is an 800 CFM carburetor. The primary outer venturi is bigger. It measures 1 7/32" vs. the 1 3/32" of the smaller carburetors. That makes the primaries 1/8" bigger, and they are jetted richer than the 750's. Stock jetting on the 7041540 was .073 jets, and 44B rods on the primary side, with AS secondary rods. Because the outer venturi is bigger, there is a tell tale bump in the outer wall to clear some internal passageway.
