1937 120 C Running problem

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Rachel@1951
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Joined: Thu Jul 12, 2018 6:07 am

1937 120 C Running problem

Post by Rachel@1951 » Thu Jul 12, 2018 6:18 am

The 1937 120 C has the Carter WD-O Carburetor. It starts, runs, and drives fine. When we sit in traffic and the engine gets around 200 degrees on the temperature gauge when we accelerate the car runs rough when we accelerate. I do not know where to start. This problem just started. The carburetor was rebuilt two years ago. We average 750 to 1,000 miles each year in the car. Any ideas on what changed?

Dave Czirr
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Re: 1937 120 C Running problem

Post by Dave Czirr » Thu Jul 12, 2018 7:11 am

Well, if the engine is getting to 200° it is running hotter than originally designed, probably just from long and gradual loss of efficiency of the cooling system components. Combine that with the fact that today's gasoline is more volatile and what you are probably experiencing is the beginnings of vapor lock. Probably more words have been written about vapor lock that you'll find in "Crime & Punishment", but you might start with a good tuneup and especially insuring that the ignition timing is NOT retarded in the least. Then the usual, fan belt fit and tension, use of a strong cooling system cleaner for the radiator and the engine block, perhaps even having the radiator removed for professional cleaning (and while it's out, service the heat distribution tube behind it). And, is the heat shield still present on the fuel pump? And some folks have added an electric fuel pump mounted back by the tank to give a boost to fuel delivery when such episodes occur.

Rachel@1951
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Joined: Thu Jul 12, 2018 6:07 am

Re: 1937 120 C Running problem

Post by Rachel@1951 » Thu Jul 12, 2018 8:12 am

Thanks for your reply. I will follow the item listed. The fuel pump does not have a heat shield. I will look at getting one.

The rough running is a recent phenomenon so again your list of item to check is a help.

Thanks.

Dave Czirr
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Re: 1937 120 C Running problem

Post by Dave Czirr » Thu Jul 12, 2018 8:32 am

John Ulrich has reproduced the heat shield.
Attachments
Ulrich fuel pump shields.jpg

Rachel@1951
Posts: 9
Joined: Thu Jul 12, 2018 6:07 am

Re: 1937 120 C Running problem

Post by Rachel@1951 » Thu Jul 12, 2018 10:05 am

Thanks. It is on its way.

Rachel@1951
Posts: 9
Joined: Thu Jul 12, 2018 6:07 am

Re: 1937 120 C Running problem

Post by Rachel@1951 » Fri Aug 17, 2018 6:34 am

Back to the running problem. I installed the heat shield, cleaned the radiator, drained and flushed the system, installed new coolant in the 1937 120 C. When the car is cold it drives fine no hesitation while accelerating. It will run up to 50 or 55 with no problem. In traffic at stop lights the temperature will get to around 190 degrees on the gauge in the car. After sitting in stop and go traffic when we accelerate the engine still hesitates like it is starved for fuel. The car will not run above 40 miles per hour. This time I turned on the electric fuel pump and I was able to get the car to 45 miles per hour with my foot to the floor. That is not right.

I bought a tune up kit for the car but I have not installed it yet.

Any ideas if the problem could be electrical?

Has anyone else had this problem?

Dave Czirr
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Re: 1937 120 C Running problem

Post by Dave Czirr » Fri Aug 17, 2018 6:54 am

It's very likely the performance of the car will improve with a good, comprehensive tune. And a good tuneup is a lot more than just replacing plugs, wires, points, condenser, cap and rotor. It should include checking fuel filters, checking fuel pump delivery volumes and pressures, battery cables, distributor advance mechanisms, etc. But regardless of any of those needs, the fact that your car is reaching 190 deg. F. idling at a traffic light says you have a cooling system problem. So by all means do a good tuneup and also check things like the manifold heat riser valve but I believe you will still have to address the competency of the cooling system further.

flackmaster
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Re: 1937 120 C Running problem

Post by flackmaster » Fri Aug 17, 2018 10:52 am

I concur/second what Dave has said. I will add emphasis (based on personal experience) to making darn sure the heat riser is fully open. This describes exactly how the car will act when the heat riser is even partially closed, or if there is any other obstruction (read mouse nest in muffler, etc) in the exhaust system...

DAF

Rachel@1951
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Joined: Thu Jul 12, 2018 6:07 am

Re: 1937 120 C Running problem

Post by Rachel@1951 » Fri Aug 17, 2018 1:37 pm

No to be too dense. Is the manifold heat riser a different name for the thermostat? If it is not please let me know.

I will continue to follow your suggestions.

Thank you.

Dave Czirr
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Re: 1937 120 C Running problem

Post by Dave Czirr » Fri Aug 17, 2018 3:25 pm

No. Its a thermostaticly operated valve in the exhaust manifold directly below the carburetor. Its function is to aid vaporization of fuel in a cold engine by directing hot exhaust gases to the intake manifold just below the carburetor. As the engine warms up a coiled thermostatic spring relaxes and a counterweight on the valve shaft drops, thus closing off the flow of heat to the carburetor, allowing the exhaust gases to pass directly to the exhaust header. If you live in a warm climate or only drive in warm weather you could disable the valve in the open position (counterweight down) and never miss it. But its function will be appreciated in colder weather.

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