I am not going to get into this argument - I don't know!
However, a bit of information.
In 1950, Carter Carburetor released carburetor YF number 788s to replace the Rochester B on 235 CID engines with manual choke. The Carter 788s is set up for ported vacuum. This carburetor was sold through early 1952.
In mid-1952, Carter Carburetor released carburetor YF 966s to supercede YF 788s. There is a calibration change, and 966s is set up for ported vacuum. Carter suggested existing stocks of 788s be used and then 966s was to be sold to replace Rochester B's on 235 CID engines 1950-1952 with manual choke.
In 1953, Carter Carburetor released carburetor YF 2100s to be used on 1953 (BUT NOT 1952 AND EARLIER) 235 CID engines with manual choke. THE MAJOR DIFFERENCE FROM THE 966s TO THE 2100s WAS THE VACUUM TAKE-OFF IS NOW MANIFOLD VACUUM, NOT PORTED! The 2100s was continued to be sold for 1953 and newer 235 CID with manual choke through the 1956 model year. The 966s was still available for 1950-1952 engines.
In 1957, Carter Carburetor released carburetor YF 3211s for use on 1957 and newer 235 CID engines. YF 3211s also has manifold vacuum.
So, as stated earlier, I am not going to get into the ported/manifold vacuum argument; but I have always believed engineers do things for a reason.
Jon.
