Holley 0-4779C Model 4150 Double Pumper 750 CFM Square Bore 4-Barrel Mechanical Secondary Manual Choke New Carburetor Mechanical secondary dual accelerator pump for additional fuel under initial acceleration Dual feed fuel inlet with mechanical secondary type Dichromate finish with center hung floats 4-corner idle system for precise control 100-percent wet-flow tested and calibrated for street drivability