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1921 Dodge Brothers Starting Problem

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Hi I'd like to ask assistance for an issue that's left me sitting  few times.   If I turn my 1921 Roadster off after running for more than about 10 minutes, it fails to start again.  It'll crank till the cows come home, but won't fire.  I initially thought possible vapor locking, as I live in the Phoenix Metro area and its been well over 100 degrees when I've driven it.  I no longer believe this is the case per below.   


Basic stuff: fuel, spark, timing. 

Fuel: I have plenty of gas.  The vacuum tank has been bypassed and fuel is being delivered to the carburetor via an electric fuel pump and variable regulator, which adjusts from 1 to 7 lbs. It's set at 2.5 Ibs.  I disconnected the fuel line to the carb and it has a lot of pressure, perhaps too much for the Stewart carb? I have a good strong battery, and plenty of spark to the plugs.  Timing must be good.  Starts first time, every time when cold, but when slightly warmed up, if I shut it off, it could be hours before it starts again.  

Sounds like carburetor to me, but I have limited experience with fuel delivery issues.  I also adjusted the regulator from 1 to 7 lbs, but with little luck.


Any reason shutting off the car after such a short amount of time would not allow it to fire?


Thank you,






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Try putting some fuel into a spray bottle and as your turning it over spray a couple of squirts into the air intake. That will prove either way if it’s fuel or not. 
If it still doesn’t start Pull the plugs and see if they are wet. If they are you may have to much fuel pressure or a bad needle and seat. They don’t like to much fuel pressure. 
After that with no change do a compression test on each cylinder. 

Edited by Mattml430 (see edit history)
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Are the plugs wet after cranking? You don't need to spray gas into the intake (would be hard as the air is pulled thru exhaust manifold preheater down through the valve chamber into the carb with a fresh air intake for warm weather down between the cylinders), unless they have been removed, 21 would have priming cups. If it runs for 10 min. my vote would be to check the condenser or maybe the coil. I think 2.5 on the fuel pressure might be too high. It would only be gravity feed from the vacuum tank which would hold less then a qt with the bottom only a few inches above the bowl on the carb., so not much head pressure.

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Thanks for additional responses.  It'll be next weekend before I can run it again.  Am hoping it's something simple, as it's starting to drop below 100 in Phoenix, and we'll have good driving weather in a month.  

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