The Stovebolt Site Forums The Shop Area Engine Shop Vaccum Advance

Question? best place to hook the VA tube to carb, I have the old auto choke hole and the bottom rear of the plate (commonly wher pwr brakes runns into).
Cavebull

Carbs original made for the 216/235/261 all had a vacuum port for the advance.
That port pulls more vacuum with increased airflow as the throttle is opened further and rpm increase.
That's really the only connection where a vacuum advance makes sense and works right.

The manifold vacuum would be a bad place for the advance as vacuum drops with opening of the throttle.

Autochoke carbs require an open tube that goes to a heat stove attached to the exhaust manifold or pipe.
Plugging that opening or connecting anything else messes with the carbs basic function.
Best to go with an Universal Manual Choke conversion kit.
Napa has a simple one.

Ok, so plug maanifold at the base. easy
You scare me a bit as I have manual choke on the primary and no choke on the dumper. Both have the ports for the autochoke tube.How bad does plugging it affect the carb function? What should I look for and could I see it anyway?

Does anyone know what/where the vacum attahment was on Roch 2 barrels?

Cavebull

Depending on the carburetor, there might be a vacuum port about halfway down the main carb body casting. Some 2G Rochesters did not have a ported vacuum fitting. The port you're looking for should have no vacuum at idle, and the vacuum should come on with a small amount of throttle opening as the engine speed is increased. The simplest way to find the right fitting is to use a vacuum gauge and look for a port that gets its vacuum at part throttle.
Jerry