Number 1 coil keeps shorting out.

[jmemjr]

I have a new one to me, my number one coil
Keeps shorting out and going dead. It’s on my 1912 that has rebuilt coils. The coil will work for about 20 minutes like clock work and then stop working. It is isolated to number one cylinder and it is making me crazy.

I have soldered brass tabs onto the buttons on the coil to add brass shim To make up for the position change of the contact and the only thing I can think of is that I used too much heat and messed up something on the inside of the coil and it’s failing when used.

Any suggestions are welcome. Trying to get it ready for Hershey and it’s kicking my butt.

[Moxie26]

Who manufactured that coil for your 1912 ?

[jmemjr]

They were rebuilt buy a notable coil rebuilder and they are KW coils

[Rich P. Bingham]

Is it the coil unit in the #1 position itself, or the #1 slot in the coil box? Have you moved the coil unit to other positions in the box with the same result ?

[jmemjr]

Yes, after failure if I move to a different position it is still a dead coil. It’s the first position in the coil box closest to the driver

[John kuehn]

Does it actually short out or does it just quit working. I had the 4 coils rebuilt in my 1919 Runabout and one of them started missing intermittently. I contacted the rebuilder and he told me to send it back to him in a good reusable box. It turned out one of the nuts on the point nuts was loose. Works fine now. You could contact your rebuilder and ask his opinion. That’s what I did.

[Ed Fuller]

Try putting a good coil in that position and slowly turn the crank over by hand with the ignition on battery. Listen close to see if the coil is buzzing continuously and causing the coil to fail.

If it is buzzing continuously, you could have a short to ground in your commutator wiring or a short to ground in the timer itself.

I had a timer short internally to ground and cause a timer to buzz all the time. Fortunately, I caught it before the coil failed.