Denny,
I have in front of me my GM manual on the new carburetors for 1952, publication #MTS-52-8 &9-S&M. Quoting from page 2 "For 1952, Chevrolet introduces a new improved GM Model B carburetor. Externally, this new carburetor has larger air horn screws, a thicker flange and heavier bosses. There are numerous internal improvements." I have the earlier carburetor and the 1952 model and with my units, the screws are larger on the 52.
