Autolite 4100 Vent Tube Replacement

Some Autolite 4100 carburetors have 4 vent tubes sticking out of the top. These are used to vent the primary and secondary float bowl. Left unvented, the gas could siphon out of the float bowl and into the bores causing a rich condition.

Autolite 4100 Vent Tubes

With the top turned over, this image illustrates where the vent tubes lead to.

Autolite 4100 Vent Tubes

This illustration shows the holes leading to the float bowls. The gasket is squeezed and sealed around the edges. At the same time there is a small open area from the top of the gasket to the bowl top. Air flows across this open area into the holes shown allowing the bowls to be vented.

4100 Vent Tube Holes

These brass vent tubes are sometimes lost by falling out, or may have gotten bent. At any rate one or more may have to be replaced. The tubes are pressed in and can be removed with a vice grip. Twist the vice grip back and forth to loosen, then pull out. If you have a stubborn one, then apply heat to the outside of the tube well. That will surely loosen it up.

Autolite 4100 Vent

To replace with the new brass tube simply tap it in using a brass drift punch. It shouldn’t take much to tap it in. If it seems loose try a little thread locker, blue, or stronger.

4100 Vent Tube
Updated on 09/25/2021

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