That looks like a local fabricated cap, so you HAVE to have a vent for the fuel tank somewhere. Irregardless of your problem, provide a vent. One other note, perform ONLY one fix at a time and test the engine.
The easiest way to check the condenser without a test meter is to simply replace with a New condenser.

Where Are You From? Texarkana, Tx

Do You own a car built by Durant? several

A long shot but check the cap on your gas tank to be sure the vent is open. If not, a vacuum will build in the tank until the "pump" can't pull out. When you stop, enough air will leak in and the car will start again.

Where Are You From? San Francisco Bay Area North

Do You own a car built by Durant? 1925 Star

If you are getting to much raw gas check that the carb float isn't sinking ( take out and shake it) or the needle valve isn't sealing.

Where Are You From? Ithaca NY

Thanks for the reply.

No black smoke, actually no smoke of any type really. It runs pretty smooth when it's running up until it warms up. Here's a video of my running it around the complex.
https://vimeo.com/132159998
It rattles because the camera was taped to the window. You can hear the engine though. (it stalls at about 8 minutes) I then turned it off.
It seems like it dumps more gas when it gets to the stalling point, especially with the air filter on.
Once it starts to stall, it gets harder to start until it won't start, and then when it cools off it's fine again. Though I don't think it's over heating really. I can still hold the radiator hose and it's only warm, not that hot.

Vacuum, luckily I do have a friend with this gauge who lives next door. I will try and see if I can get out this week and find out what's going on there.

If it's a timing issue, is this something that can be resolved by manually turning the distributor? It is supposed to have a spark advance lever I THINK... as there is the switch on the steering wheel, but no rig between the steering column and the distributor. I wouldn't know exactly how to judge it as it runs fine until it is stalling.

Timing: The timing was initially looked at. We had the crankcase off and put new gaskets in. We turned it to top dead center and checked the valves. The position of the engine seemed to match where we marked the chains and gears when it came off so it seemed like it probably was in the right position. We spent some time grumbling about the lack of indicator on the gears. There were a couple of circles but it was hard to tell what they were supposed to be pointing to so we did everything manually. It fires and starts smoothly though.

Gas dumping isn't a new issue. I thought originally it had something to do with the float in the carburetor, (before we serviced the chaincase gaskets) No matter what I tried I couldn't get it to stop dumping gas after it was shut off. So I got a new carburetor. Unfortunately it is still having that same issue, so I am thinking this may be something else.

THanks for the input

Where Are You From? Langley BC

Do You own a car built by Durant? Yes - 1928 Durant M2

That's an interesting thought. Sort of like a vapor lock. I will check that, I'm not sure where the vent is however. I guess if enough suction were to build up, maybe that's why the gas doesn't quite get to the engine, and when it's turned off, the engine isn't trying to suck it up anymore, the back pressure would pull the gas out the carburetor...that might be possible.

I am unfamiliar though where the vent is. If that's the issue, that would be I think I much easier fix.

I will check.
THanks

Where Are You From? Langley BC

Do You own a car built by Durant? Yes - 1928 Durant M2

I looked at the gas cap. I don't see any vents. Is that something that is supposed to be on the cap or the tank. The cap is solid metal and screws on tight. No holes.

Alright, so I took the cap off, put some wrap over and elasticed it on to the tank, and poked a hole in to it, then ran the car for a while. The car is still stalling when it warms up even with the hole in the gas covering. So I am guessing it's something else.

Where Are You From? Langley BC

Do You own a car built by Durant? Yes - 1928 Durant M2

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

Where Are You From? Leavenworth, WA / Yuma, AZ

Do You own a car built by Durant? Yep

Gearald...Heres's what I think is happening and could explain all your symptems....Your vacuum tank is malfunctioning, it is not shutting down properly at the top of it's fill cycle...You mentioned that you have 8 minutes of run time before the engine (warms up? or something else) and stalls...I am thinking that it takes 8 minutes for your vacuum tank to make a complete cycle from being overfilled from your previous failed cycle, to the time it fails at the top of it's next fill cycle...when your vaccum tank overfills to a point, raw gas will be sucked directly through the vacuum line into the engine and flooding the engine...The vacuum line enters the intake manifold directly above the carburator on a W-5, you mentioned that gas would drain back out of your carburator during shutdown...I am thinking that the gas is not draining from your carburator but through your carburator throat from the residual raw gas left in the intake manifold and vacuum line....Somehow the float valve must reset itself and after a while you are able to restart your engine and you are up and running good until the next cycle occures....I'm not up on vacuum tanks but a plugged vent, saturated float, broken float toggle spring,leaking valve are a few things that can go wrong...

Where Are You From? Leavenworth, WA / Yuma, AZ

Do You own a car built by Durant? Yep