C3 Corvette Carburetor Numbers

Identifying your Quadrajet

Most C3 Corvettes left the factory with a Rochester Quadrajet four barrel carburetor, and Chevrolet stamped an identification number directly into the carburetor body to record exactly which calibration it was. On carburetors built from mid-1968 onward, look for it on the driver's side of the float bowl, near the secondary throttle linkage. On earlier units it was stamped around a small round tag pressed into the bowl.

That number ties the carburetor to a specific model year, engine, and often transmission and emissions combination, since Quadrajets were calibrated differently for each application. It is a quick way to check whether the carburetor on your car is the correct original type, or a later replacement, and it matters for anyone chasing a numbers-correct restoration. Look up your carburetor's number in the table below to see what it was originally built for.

Reading the number itself

There is a pattern hiding in these seven digit Rochester numbers that saves you a trip to the table. The last digit tells you which transmission the carburetor was calibrated for: an odd number means a manual car, an even number means an automatic. Run down the 1968 list below and you can watch it work. The 300 horsepower manual car got 7028207 while the same engine behind a Turbo Hydra-Matic got 7028208, the very next number up.

That single digit is worth knowing because it is the mistake most often made when someone buys a carburetor secondhand. A manual calibration bolted onto an automatic car, or the other way round, will run, and to the eye it looks perfectly correct, but the part throttle response and the shift feel will never be quite right. If you are staring at a swap meet table full of Quadrajets, checking whether that last digit is odd or even takes a second and tells you a lot.

When your number is not in the list

Plenty of C3s are wearing a carburetor whose number appears nowhere below, and that is not automatically bad news. Chevrolet sold service replacement carburetors over the parts counter for years, and those carry their own numbers that were never assigned to a production car. A number that is close to a listed one but not an exact match is very often a service unit, and it may well be the carburetor a dealer fitted under warranty when the car was almost new.

It is also worth keeping two different ideas apart. Having the correct carburetor number means the right type of carburetor is on the car. Having the original carburetor means it is the actual unit that left the assembly line on your Corvette, which the casting date can help you confirm. For most owners who simply want the car to run and look the way it should, the first is what matters. Only judged, numbers-correct restorations really need the second, and the gap in price between the two is considerable.