VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 '31 runs rough with spark knob pushed in

I have a 1931 4 door sedan that my dad restored a couple of years ago. Today it started running rough and quit a couple of times. It starts ok when the spark knob is pulled out, but when I push in the spark knob it starts to run rough. I took the distributor cap off and on and checked all the connections and it seemed to run ok for a short while. Then it started cutting out again. If I pull out the spark knob it runs ok and I was able to get home. Is there a troubleshooting sequence I should go through? Thanks.

Hi there and welcome to Chevy Chatter II. Glad to have you with us.

Sounds like you might have a bad connection between the end of the electrolock and the points inside of the distributor. With the car running, jiggle the electrolock near the distributor and see if the car runs better or worse. If you get a reaction one way or the other, then I definitely would look at the electrolock connection at the distributor.

Also, just for grins, check your timing as well.

Hello 3rdgen31,
I don't have the knowledge and experience that the Technical Advisors have, but my guess would be to check your wiring from the ignition switch to the distributor (especially around the distributor) for possible frayed wire or faulty insulation grounding out the ignition. You say that with the spark knob 'in', the engine misses and quits, but with the spark knob pulled 'out', the engine smooths out and continues to run. Rotating the distributor with the spark knob may be just enough to keep an uninsulated wire from grounding out the ignition. With the engine running, try moving the wiring around by hand, simulating vibrations during driving to see if you can recreate the problem. You should also verify that your timing is set correctly with the spark knob 'in'.

If his car still has the original electrolock, then he will not see any wiring because the wire going from the "pop-out" ignition switch to the distributor is inside of the electrolock armored cable.

It is common for the insulation on the center wire in the electrolock to deteriorate and when the cable is moved to short to ground. Moving the cable while the engine is running will fairly quickly determine if that is the problem. Another cause can be the connection to the distributor as suggested by the Doggie guy.

Thanks, I will try the solutions posted hopefully this week and let you know what I find out. Time seems to be in short supply.

Hello Junkyard and 3rdgen31,
My 31 Coach does not have the electrolock system. That must have been removed long ago. It currently has a cloth insulated wire from the cowl mounted coil to the distributor/condenser terminal. Junkyard, what is your opinion of the electronic ignition conversion for Chevrolet in the Sept. 2010 G+D article on page 35? Old school vs New, Daily Driver vs Show, Original vs Change? Would the Electrolock be effected? The term 'The way of the buggy whip' comes to mind. 'The way of the points' relegated to the past.

The point system is not only simple, it is fool proof and extremely reliable. If you have to change the points while on the road it is easy to do. Not so with electronics. "If it ain't broke don't fix it!"

Though you did not address this reply to me I will respond. I know personally the results of running the electronic conversion on a 1928 Chevrolet engine. The unit performed well as a replacement of the points. It did require (as specified by the manufacturer) a minor alteration of the wiring and there is the Caution to not have the ignition switch in the "on" position for an extended time without the engine running or the unit could be overheated and damaged. Without doing side by side or other scientifically based testing any comparison of the performance of the system to the original points is merely conjecture or guessing.

The electronic unit continues to be in the '28 and is performing well. A points distributor is carried as a backup. Just remember that both units are essentially just switches. Yes the solid state switches have no direct contact points to eventually fail but replacement of the points is not a difficult job and the parts are readily available and not expensive.

I took the '31 to my dad's last weekend. He is going to go over the distributor and check all the connections. Once we figure this out I will post what was found.

It looks like the problem is solved. Dad checked the end of the electrolock connection in the distributor and the nut was loose in there. While he had it apart he ran a new wire inside it. I drove it home today and it seemed to run ok. Thanks for all the help on this problem.

I enjoy reading the forum just to be able to learn a few things about these old cars.

That looks just like the 31 I had in my garage for the last 43 years.Could that be the same one?
Just kidding I am the second gen my dad was the the first goes to show you those old chevrolets might outlast all of us.

Yep, that is what we suggested back in the middle of September. Glad that you were able to find the problem and that you are now back on the road. Cool!