Throttle Shafts and Bushings

Loose throttle shafts will cause two problems.

1. Too much air which will act as a vacuum leak. Spray carb cleaner around the throttle shaft. If the RPM changes then the shaft is too loose.

2. Allow dirt into the carburetor and engine. This is the chief cause of carburetor and engine failure.

We don't know, these are a repair part and have to be matched to your carburetor by sizes. You will most likely need to remove your throttle shaft in order to determine which bushings you should purchase.

The outer dimension of the throttle shaft should match the inner diameter of the bushing. You'll have to ream the carb bore to fit the outer diameter of the bushing.

We have a handful of shafts available, you can find them here. These are not listed for any specific carburetor number, you will have to match your existing shaft to be sure you're ordering correctly. Most choke and throttle shafts are not available aftermarket.

Movement of .010" or more means it's time to repair the throttle body. This can be difficult to measure so estimate anything over 1/32" in sideways movement as a worn bushing. If the throttle shaft itself is worn, you'll need to find a replacement. If the shaft is in good condition but the bore is worn, you can have someone rebush the carburetor bore to tighten up the throttle shaft. 

Rebushing the throttle shaft of a carburetor is a delicate and precision-oriented task that requires proper tools and expertise. It can be done by individuals with advanced mechanical skills and experience working on carburetors. Here are the general steps involved:

1. Disassembly: Remove the carburetor from the engine and disassemble it completely, taking note of how the components are arranged.

2. Throttle Shaft Removal: Carefully remove the throttle shaft from the carburetor body, ensuring you don't damage it or any surrounding components.

3. Bushings Removal: Remove the old bushings from the throttle shaft and carburetor body. This may require specific tools and techniques.

4. Cleaning: Thoroughly clean the throttle shaft and carburetor body to remove any residue or contaminants.

5. New Bushings: Install new throttle shaft bushings. Make sure they fit snugly but allow for smooth rotation of the shaft.

6. Reassembly: Reassemble the carburetor, ensuring that all parts are correctly positioned and tightened.

7. Testing: Test the carburetor's functionality after reassembly. Ensure that the throttle shaft moves smoothly without binding.

8. Tuning: Adjust the carburetor settings as needed to achieve the proper fuel-air mixture and engine performance.

If you're not experienced with carburetor work, it's advisable to consult a professional mechanic or carburetor specialist to perform this task. An improperly bushed throttle shaft can lead to performance issues and potentially damage the carburetor.

Example of a bushing installed on a Holley 1940 throttle body:

No we don't. Again, we don't recommend rebushing for a DIYer. We sell individual bushings for rebuilders and mechanics, we don't offer the tools required for installation.

Not necessarily. There should be no fuel in direct contact with the throttle shaft. When a carburetor floods, fuel overflows the throat of the carburetor, runs down, and out around the throttle shaft which is the point of least resistance. If a throttle shaft was totally sealed, it wouldn't be able to move. If you have fuel leaking around the throttle shaft, you'll need to figure out why the carburetor is flooding.

The throttle shaft is always suspect if you think you have a vacuum leak, especially from a rough idle condition. Spray carb cleaner around the throttle shaft with the engine running, if you hear a change in the RPM, your throttle shaft is allowing air to flow from atmosphere to carb bore, it needs to be replaced or re-bushed.