VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1933-1936 problem puzzle?

My 1936 has always had what feels like a continuous stumble while driving. It is not as noticeable accelerating or de-accelerating, just while cruising along. It diminishes if I retard the spark a bit or add a bit of choke ( \ ). It seems to do it more if I turn on the headlights, (but that may just be my imagination). The puzzle remains after I have replaced the carb twice, the coil, points, condenser, Vacuum advance unit, and fuel pump to electric W/ regulator. It did this with new plugs and wiring. Anybody have an idea of what I can check next. This car has a new block with about 2500 miles on it and it has done this since new.

I had a stumble like this once. It ended up being a short in the wiring harness that would arc to ground. The metal clamp that held the harness in place had worn throught the cotton brading and caused a intermittant short. I noticed this in the dark with the hood up when I was trouble shooting the stumble.

Check your wiring harness for worn, chewed, or under the metal clamps for cuts in the insulation.

I would hook-up a vacuum gauge to see if it offers any clues...

I would encourage everyone from time to time to observe the ol clunker idling in the dark...You might just find a leaky wire..

Do you have an amp gauge in your car?If so,see if it goes toward the discharge side each time it stumbles.That would possibly steer you toward an electrical problem.

Good ideas, I think I will hot wire the ignition and disconnect the factory harness. Can't figure out why choking it a bit would help a short tho.

I just fixed this very problem on my '50 convertible. It was difficult cranking, wouldn't charge, ran rough, and sounded like it had dropped a cylinder. I found a wire in the socket connection where the turn signals connect into the lighting system that was grounding out. After I fixed that, all of the other problems went away. Like you said,it was difficult to find the problem because it was hard to even tell where it was occurring. I basically found it by unhooking every wire in the car outside of the ignition system, then hooking them back up one by one. There are a lot of impossible to reach wires in a 1950!!

I too experienced a similar happening with my freshly restored series one landie back in 1992.
I eventually traced it to the distributor.
underneath the points support plate, where the weights live, there was a small wire, covered with the old fashioned hard brown insulation. Over 50 years, the insulation had broken down into small sections and on bumpy roads, the bare parts shorted out. It was a devil to find and once the insulation had been repaired, it never missed or misbehaved again....
Peter