From 1967 through 1972, the venerable Quadrajet carburetor was used on many Chevelles ordered with standard performance engines, and those applications will be the focus of this article. Quadrajets were manufactured by Rochester (a division of General Motors) and Carter carburetors. Outsourcing carburetor production allowed delivery to meet demand as the Q-jet was used on other Chevrolet models and virtually every other GM nameplate as well.
With so many carbs in production for a myriad of applications, finding the right one for your Chevelle can be a challenge. There are a couple of locations containing the codes needed to identify your Quadrajet; both are located on the driver side of the carb body. Early Q-jets used a circular tag stamped with the codes found in a cavity in the side of the float bowl, while later carburetors used a stamping on the body of the carb.
Breaking down the carb codes is fairly simple once you have some basic idea of how the system is setup. Information included in the stamped alpha-numeric codes are the model/application number (usually seven digits), and a date code. All Carter-built Q-jets have "Mfd by Carter" cast into the carb body, although the carb numbers (application codes) are the same as Rochester-built carbs.
Outin' The Code
The stamped part number decodes as follows:
Example: #70 4 0 2 0 5 EH 0260 70 = Prefix code. "70" will appear on all Q-jets through 1976
4 = Decade produced (ie: 2=1960's; 3=1960's with A.I.R.; 4=1970-1975)
0 - Year produced. 0=1970
2 = Model (ie: 2=Quadrajet (4 bbl) Federal standards;
(4 bbl) California standards)
1 - Division. 0, 1, and 2 all indicate Chevrolet.
9 - Transmission (ie: Even numbers=Automatic Trans; Odd numbers=Manual Trans)
DG - Customer code (assigned for each application, matches carb code on build sheet)
0260 - Julian Date Code (026=26th day of the year; 0=year of production, 1970)