Thanks for the info.

I guess it depends on year and whether its a DeLuxe or not. . .

If it was fitted with an elbow, then it has a ball check valve inside it that is supposed to seal the passage when the engine is running.

The original reason for the drain was to keep flooding from being an issue. They used them on a lot of cars when downdraft carburetors were introduced (for Plymouth that was 1933). On an updraft carb any excess fuel would just run out the air inlet but they worried that on a down draft it would puddle inside the intake manifold.

Not sure I've ever seen one of those drain elbows on a post WW2 car. So either they decided it was not necessary or they decided that people learned to hold the throttle down while they cranked the car to clear the condition.

What every you do, don't just put on a plumbing store elbow fitting without the check valve built in: You'll be introducing a vacuum leak that will make getting the mixture correct impossible and likely lead to burning valves due to lean mixture.

My '36 intake manifold has a solid stud with a thermostat counterweight stop on it. Some parts books and parts photos show an elbow fitting and tube at the outer end of the stud, assuming this stud is hollow and allows for drainage. Is this correct, and is this drainage
feature ( if that's what it is for) necessary? Could the drainage tube draw excess air back into the manifold or cause any other problems?
Thanks. LR