Articles

Quadrajet History and Design

SUMMARIZED FROM THE BOOK: “HOW TO BUILD AND MODIFY ROCHESTER QUADRAJET CARBURETORS” BY CLIFF RUGGLES The Rochester Quadrajet was a standard production four-barrel carburetor used by every General Motors division for nearly 20 years. Although it never deviated far from its original basic design, the Quadrajet underwent several modifications over the...

Electric Choke Q-Jets

An electric choke can significantly improve cold-weather operation over other original choke styles. Any carburetor originally fitted with a hot-air thermostatic choke coil can easily be converted to the later GM electric choke. However, to prevent a vacuum leak, the hot-air choke uses a gasket between the choke coil...

Quadrajet Casting Number Chart

  Through the years of production, the manufacturer used numbers for carburetor identification. Very early Quadrajets had tags installed into a cast round area on the drivers side of the main body.     In and after about 1968, stamped numbers were used for identification. The large flat area on the main...

Quadrajet Model Designation Descriptions

Although many castings are referred to by specific characteristics such as airflow capacity or choke type, Rochester actually gave each Quadrajet style different designations indicating body type and choke style. The first design series was designated 4M and can be found on all GM vehicles through 1974 and on GMC and...