What is this ceramic thing on my coil?

Thu Mar 23, 2006 8:36 pm

I bought all new plugs, wires, dist. cap, rotor, condensor, points, etc. and started to put them on the tractor today. Well, almost. I shined up the starter face and it helped a lot as well as shining up the ground cables etc., but there was a lot of frying and sparking and zapping inside the new starter switch I bought, and I imagine it probably now looks like the old one, eg. black and partially melted!

I took off the coil and noticed I didn't have a recognizable condensor on it like on my Cub. That is, assuming I'm correct in assuming that little silver cylinder is the condensor... In its place was this little ceramic block, approximately 1 inch longer than the silver cylinder type and under which there was a wire-wrapped fiberglass element burned in half and corroded near one end.

This thing had wires connected at both ends, one coming from the coil and the others passing on I think to the solenoid on the fuel line and the other up into the dash somewhere (sorry it was getting dark and I couldn't tell exactly where in all that schmoo it was going.)

Any idea what this is, and why I don't have a little silver cylinder on there, and what the heck do I do now?



Thu Mar 23, 2006 8:39 pm

Allen - that is a ballast resistor.

Thu Mar 23, 2006 8:46 pm

OK BigDog, I believe you... I still don't know what to do with it :D

Do I replace it in kind, do I replace it with a newfangled device, or do I leave it out? Do I still install the condensor?

I'm afraid this is my first excursion into the electrical side of the tractor.

Thu Mar 23, 2006 9:16 pm

A balast resister gives a voltage drop from 12 volts to 6 volts. The coil you have needs 6 volts. You have a 12 volt battery there fore a dropping resister.


Thu Mar 23, 2006 9:18 pm

or a 12 volt coil. (I'm assuming you are working with a 12 volt system.

Thu Mar 23, 2006 10:29 pm

Allen, that ballast resistor looks like the one I had on a 1955 Packard. It was bypassed when starting the car, and then in play when the ignition switch was in the run position. Reduced the voltage back to 6 volts for the ignition system. I think you definitely need the resistor and should replace it. There may be a resistance value marked on the shell. . Bill


Fri Mar 24, 2006 6:53 am

Yep, this is a 12V system (battery at least is 12V), and I've bought a new 12V coil for the tractor.

The starter is 6V but I don't think that's a problem using it with 12V...

Will everything else in the system be OK if I leave this out and put in the new 12V coil?

Fri Mar 24, 2006 7:15 am

Allen, Some 12 volt coils have resistor built inside, some don't. Be sure to get one with the resistor built in. Bill

Fri Mar 24, 2006 7:22 am

I got one at NAPA. They had two different ones, for $56 and for $26, so I got the one for $26...

Fri Mar 24, 2006 2:44 pm

A 12V coil is a 12V coil. It's got to have a built-in resistor, or it needs to be wound for 12V. Either way, putting in an extra ballast resistor would make the spark weak.

Fri Mar 24, 2006 5:37 pm

I put the coil on today, and it says right on the side of it, "12V, No External Resistor Required", and everything's working great. :)

Fri Mar 24, 2006 8:15 pm

Fingerprint remover. Learned that one the hard way!

Fri Mar 24, 2006 8:18 pm

That's a fact Lawrence! Done that a time or two.


Fri Mar 24, 2006 8:26 pm

Do you mean you got bit by the coil?

Fri Mar 24, 2006 8:32 pm

She gets kinda hot. Real hot.