1935 Packard Intake Manifold Leaking Fuel from Drain Valve

[carbdoc]

I restore carburetors professionally, and I recently restored a Stromberg EE-23 carburetor for a 1935 Packard Straight Eight.

The carburetor does not leak visibly when left full of fluid overnight, but the technician who installed it on the car complains of a significant amount of fuel pouring from the drain valve which Packard engineered beneath the intake manifold. It only does this immediately after the engine is shut down, suggesting that fuel is collecting in the manifold as the engine runs. It requires only a short time of idling to cause this to happen, so it is not fuel percolation. Understandably, the tachnician blames the carburetor.

I have tested this carburetor in my shop (off the car) every way I know and I can't get it to leak -- but then, it is not mounted on a running engine.

My only theory: some Stromberg carbs have check valves in the idle jet tubes, but this one does not. I cannot verify whether it is supposed to have them. Could this be causing the problem? Or is there some other problem unique to these cars with which one of my fellow AACAers might have some experience?

[Guest Snopack]

Carbdoc:

This is normal for that Packard and is the reason for the drain,

On a cold engine the fuel condenses in the manifold due to the air moving thru the manifold under a vacuam, same thing cause airplane carbs to freeze up. If the engine is shut down before the intake manifold gets warmed up and the fuel evaporates then the fuel will run out of the drain, sometimes quite a bit of fuel. Tell them to drive the car about 5 miles and then see if it drains. Idleing causes more fuel condensation as the vacuam in the manifold is at 18-20 inches.

Sincerely, John