The Rochester model H, HV carburetor was used on Corvair engines from 1960 to 1969 and several marine engines. The "H" carb was used on all Corvairs with 2 carburetors. The High Performance Corvair came from the factory with 4 carburetors, 2 "H" carbs used as the primary barrels and 2 "HV" carbs used as the secondary barrels.