Manifold vacuum pressure question on a '63

[JanZverina]

I was getting rid of an ancient electronic ignition kit that must have been installed decades ago on my '63 (does anyone remember a Sorensen ignition module?), when I noticed that the metal tube from the carb choke to the rear of the passenger-side exhaust manifold was broken near the manifold. I didn't spot it at first because the metal tube is covered in a braided heatproof wrap. My question is, would that break be a source of manifold vacuum loss, or is it not related to intake vacuum and just a pre-heat function to release the choke faster?

Thanks!

[Jim Cannon]

I was getting rid of an ancient electronic ignition kit that must have been installed decades ago on my '63 (does anyone remember a Sorensen ignition module?), when I noticed that the metal tube from the carb choke to the rear of the passenger-side exhaust manifold was broken near the manifold. I didn't spot it at first because the metal tube is covered in a braided heatproof wrap. My question is, would that break be a source of manifold vacuum loss, or is it not related to intake vacuum and just a pre-heat function to release the choke faster?

Thanks!

It is not related to engine vacuum. As you say, it is just a source of heated air for the choke.

[TexasJohn55]

Jan,

I can't speak of all makes and models but if vacuum is used to pull heat up the stove tube, it is an insignificant leak because it would be orificed. To verify, unscrew the line fitting at the choke housing and place your finger over the fitting while engine is idling.

[1965rivgs]

Jan,

I can't speak of all makes and models but if vacuum is used to pull heat up the stove tube, it is an insignificant leak because it would be orificed. To verify, unscrew the line fitting at the choke housing and place your finger over the fitting while engine is idling.

John hit the nail on the head. The choke housing is under intake vacuum via a port in the carb body. That is the reason there is a gasket under the choke housing cover.This encourages the flow of heated air thru the tube. This metered vacuum leak does not affect driveability.

Tom Mooney