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Post War Intake Manifold Drain mystery solved.

From the June 1, 1949 Service Counselor (Vol. 23, NO. 6):

Intake Manifold Drain for Custom Eights

An intake manifold drain valve is now being installed on all Custom Eight engines in production. This valve may be installed on 22nd series Custom Eights and all prior model Super Eights. It is located at the rear of the manifold for the purpose of draining accumulated fuel from the manifold. In some cases of hard starting fuel settles and accumulates at the rear of the manifold adjacent to number 7 and 8 intake ports.

When this condition exists this fuel sometimes enters the cylinder and since it is not compressible causes damage to the piston or connecting rod on the compression stroke.

The valve may be installed on cars not so equipped by drilling the manifold at the point shown in the illustration and tapping with a standard 1/8 pipe tap. The manifold should not be tapped deeply since the connector should be as near flush with the inside of the manifold as possible.

The valve is supported by a clip attached to a special pipe plug stud installed in the second oil gallery plug hole from the rear of the gallery.

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JD, Thank you, I learn something new everyday.
John

AHAH! It's all clear now, and thanks for the research. It was a running factory change with a dealer-installation option which explains why it's only found on some cars. I've still never seen one installed.

What is the purpose of the tubing that runs parallel to the length of engine and is attached to the same fastening bracket as the anti-puddle valve tubing? Interesting comment about raw fuel causing problems in cylinders 7 and 8. My '47 Custom Clipper is not fitted with one of these anti-puddle valves.

(o{I}o)

Believe that horizontal tubing is the vacuum line from the fuel pump assist section to the windshield wiper motor.

Does anyone know if this feature was ever added to the junior six engine? I am having difficulty getting the engine restarted after a long hot run. I have checked and replaced many items: battery, coil, points, cap, timing, carb and choke adjustment, fuel pump. I believe my 39 Six is percolating, and essentially pooling and flooding.
Pat

Most carburetors (not sure about yours) have an anti-percolator valve. You might check first to see if yours has one, and if it's properly adjusted.

OD,
Thanks for pointing me in that direction. My 39 Six has a Carter 530S and after my last posting, I pulled out some original literature on it. The two page document includes text instructions to adjust the Anti Percolator valves, but I have not yet become familiar with how Carter implements this and therefore, what to do. The literature does not specifically show the valves.

I have assumed that the valve either blocks the flow path into the carb bore, or opens a pathway out of the carb for fuel to drop to the ground, kinda like the tube from the manifold on the Su8.

I'll be trying to figure this out over the weekend. Thanks again for the guidance,
Pat

Based on other Carter carbs of the era, the antipercolater valve is a vent which opens the fuel bowl to the atmosphere just as the throttle valve is closing. Generally it's located under a small cover which is held down by a couple of screws, usually the same cover also encloses the linkage for the accelerator pump, though I'm generalizing a bit here and too lazy to look up your particular carburetor. There should be a metal tab attached to a shaft that opens the valve as the throttle closes, thus allowing any pressure to vent. I'm not aware of any that perform as you have suggested. If the valve (or valves) don't open when the throttle closes, heat rising from the engine will cause the fuel to expand, perhaps partially vaporize, and be forced into the intake manifold via the main jets.