The Zenith model 1510MV was a large, single bore updraft carburetor, which featured an unusual quadruple venturi. It was used on various large gasoline engines, including the 2181 cubic inch Hall-Scott model 3368 Defender naval engine in WWII, which used four model 1510MVM4 carburetors (Zenith carb # 9639).
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How to find Zenith carburetor numbers