The code numbers of a Holley carburetor are usually located on the side of the air horn. You will find that the Holley model number of the carburetor is there, along with the automaker part number if it is factory issued, as well as a date and application code. So you should look for the lone four-digit code.

After determining the carburetor is a Holley, look for the code numbers, usually located on the side of the air horn. The Holley model number is present along with the auto maker part number, if factory-issued, a date and application code. Locate the lone four-digit code. Other manufacturers do not use a four-digit model number.

Holley carburetors are popular among muscle car enthusiasts, and they are known for their high-performance capabilities. Holley carburetor identification numbers are typically stamped on the air horn or main body. Most "list" numbers consist of a four or five-digit number, followed by a dash and an additional one or two number suffix.

Most square flange Holley carbs have the "List #" stamped on the front, driver's side of the choke horn. Dominator carbs have no choke horn and their list # is stamped on a flat portion of the venturi area on top of the throttle body. The newer "HP" line of four barrel carbs have the "List #" on the driver's side of the throttle body.