The Rochester AA was the first carburetor produced by Rochester. It was an unusual two barrel downdraft carburetor used on the 1949 and 1950 Oldsmobile Rocket 88 and 98, and has very little in common with any other Rochester carburetors. Sometimes referred to as the 'turtleback' or 'flat-top', it was an unusual design with a horizontal fuel inlet and the float bowl suspended above the air inlet in order to keep the fuel cooler for better metering and hot restarts. The 'concentric' design resembles the Holley 885 used on 1949-1951 Mercury V8's. Some 1949-1950 Oldmobiles used a different horizontal air inlet carb which was a special version of the Carter WGD.
Carburetor numbers were stamped on a triangular brass tag.
Rochester carburetors listed by carburetor number