One day a feel years ago our durant died and could not restart until it completely cooled down restarted right after a rain storm. I call and talked to Jeff Gillis, he told we to get the car started, run until hot then place my hand on the Rad.
and feel for hot and cold spots. This will tell you if the Rad is blocked
A block rad will cause it to over heat and cause the engine to die, and not restart
then when cooled down would restart. Another idea to try.

Where Are You From? Muskegon, Michigan is

Regardless of your current problem, you will need a hole in the gas cap. A sixteenth of an inch should be enough.

Many of these cars will drain gas out of the carburetor when shut off. Many of us have installed a shut of valve under the vacuum tank.

Another wild guess: When the engine gets hot, electrical components can break down most notably the induction coil. Like the condenser, the easiest way to check for this is a new coil. Napa carries a 6 volt coil for old VW's which works fine.

Similarly, I had a stalling issue that was solved by running a ground wire from the distributor case to the generator case. This stalling, however, was intermittent.

Vince

Where Are You From? San Francisco Bay Area North

Do You own a car built by Durant? 1925 Star