Packard Forum Index » Pre-War (1899-1942)

How does heat get to the thermostatic choke (Carter WA I)?
Is the air flowing from the tube through the exhaust manifold and then through the spring, or does the heat merely diffuse into the chamber.? Reason for question: the manifold has rusted through the tube and exhaust crud got into the tube and the control chamber. A temporary solution would be to elongate the tube through the manifold so the opening is remote from the leaking area ,- I think this would work if heat diffuses in the tube, but might not get warm enough if the heated air actually flows through. Comments?

A very small amount of manifold vacuum within the carburetor is diverted to the Climatic housing and draws the heated air from the choke stove in the manifold to the Climatic bimetallic spring.

The tube from carb is inserted a very slight distance in the tube which is fixed to manifold. That rusted out tube just heated the fresh air coming in from the bottom which was then passed into the tube going to carb. No actual exhaust gasses were admitted to choke housing.

If you cannot replace the rusted out tube with another piece of steel tubing easily then I believe doing as you propose -- running the carb tube completely thru the manifold -- would serve the same purpose but it could be problematic for future work or removal. Unless there is enough of the old tube left and it is a large enough diameter the complete length to pass the carb tube all the way thru then the elongated tube would have to be sealed in some way so there is not an exhaust leak at the manifold.

Or you could just clamp the tubing from the choke housing to the outside of the exhaust manifold. There should be plenty of heat to operate the choke thermostatic spring. No need to have the tube exposed to the inside of the exhaust manifold.

(o{}o)

JW, That's what Tim from Carburettor Service Company in Sydney did when he rebuilt and reinstalled the carb on my '41 120. Works well.