Introduced at the dawn of the emissions control era of the early 1960s, the “spread-bore” Rochester Quadrajet carburetor was considered leading-edge fuel delivery technology for the time. The “spread-bore” configuration consists of two small-diameter primary venturis designed to maintain high primary air velocities during normal driving for maximum fuel economy and low exhaust emissions. The two large secondary venturis are designed to produce maximum intake airflow and fuel delivery for maximum horsepower output.

Shortly after its introduction, mechanics unfamiliar with the principles underlying the design pronounced the Quadrajet a “junk” carburetor. Fortunately, drag racers competing in the National Hot Rod stock engine classes soon found that the carburetor responded well to various “tweaks” and the carburetor soon proved its worth in the performance market. Currently, the Edelbrock Corporation manufactures several different versions of the Quadrajet for performance applications. A number of aftermarket racing carburetor specialists also rebuild and customize Quadrajet carburetors to fit various restoration and performance applications.

Design Features
Unlike any other carburetor on the market at the time, the Quadrajet nestled its float bowl between its two primary venturis so that intake air would cool the float bowl assembly. The float bowl’s fu...