How to Identify the Rochester 4 Jet Carburetor Number: Step-by-Step Guide
The Rochester 4 Jet carburetor, also known as the "4G" series, was a popular 4-barrel carb used on many GM vehicles from the 1950s through the early 1960s. If you're restoring or rebuilding one, identifying the exact carburetor number is essential for getting the correct rebuild kit and parts. This guide shows you how to find and decode the Rochester 4 Jet carb number.
Where to Find the Rochester 4 Jet Carb Number
The carburetor number (also called the, part number, or ID tag number) can be found in one of these places:
1. Stamped Tag on Top
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Location: Attached to one of the air horn screws (top cover).
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Format: Typically a 7-digit number starting with “7” or “70” (example: 7003537).
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Tip: These tags are often missing, especially on older carburetors.
How to Decode the Rochester 4 Jet Carb Number
Most Rochester part numbers follow this format:
Example: 7003537
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70 – Rochester carb prefix.
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03 – Year code (example: 03 = 1963, depending on context).
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537 – Unique identifier for engine and application.
Cross-reference this number with a reliable carburetor part catalog or use it when ordering a rebuild kit.
What If the Tag is Missing?
If the ID tag is missing:
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Match the old gaskets and the accelerator pump with the pictures we have for each kit. You will need the total length of the pump along with the cup size. The cup will be 3/4" for big block, or 21/32" for small block engines.
Related Resources
Pro Tip:
If you're unsure, take clear photos of your carburetor parts and send them to use at [email protected].Typical 4 Jet Installation
