Coil question

[jake]

When the car is running, how many volts should be at the positive side of the coil? I believe my coil is overheating because I get around 20 miles and the car instantly shuts off, no stumble or anything. Coil is hot as can be. Give it 10 minutes, she fires right up, go about 100ft and she kills again. Once everything cools down completely, she will go another 20 miles give or take.

Thanks in advance.

 

[Big_John]

You would be better off measuring the resistance of the ballast resistor.

Should be 1.2 ohms for a single and 1.2 and 5 ohms for the double resistor.

That limits the amount of current to the coil.

Most likely it's a bad coil, but if it's a points type distributor, check the point gap. Too much dwell (points closed too long) and the coil will overheat.

 

[Davea Lux]

If your coil is getting hot enough to stop working, it is most likely shorted out and toast. The other possibility is that somebody wired past the ballast resistor and you are getting a full 12.5 to 13 volts all the time, that would overheat the coil.

Dave