Coil Issues

[Beamin]

For some reason, my coil gets super hot if the ignition switch is left on without the car actually running. I don't know if this occurs while the engine is running as I'm still chasing other gremlins that are preventing that from happening.

I'm runnning a positive ground system, and using a ballast resistor. The wire from the ignition switch connects to one terminal on the ballast. The other terminal on the ballast connects to the (-) term. on the coil. Also connected to the (-) term is the wire coming from the solenoid, which, if I understand correctly, provides a higher voltage to the coil during starting. The (+) term. of the coil is connected to the distributor.

Do I have this wired correctly, and if so, would these symptoms be indicative of a bad coil? If not a bad coil, then what?

Thanks,
Andy

 

[Green67Alpine]

Andy, Check the archive forum, I asked basically the the same question and got a few insightful replies.

tom J

 

[Beamin]

Heck, if it wasn't for the info on the archived forum, I wouldn't have gotten this far, but I didn't see anything about a hot coil even when the car isn't running. Did I glance through too quickly and miss something?

I did just stumble upon another symptom. I noticed that when everything is hooked up the way I think it is supposed to be (which may or may not be correct...), if I turn the key to the on position, I show a negative draw on the ammeter. Interesting, given that nothing is actually turned on. If I disconnect the lead from the ignition switch to the coil, there is no draw. This would seem to indicate to me some sort of short, either in the coil or distributor. Got to go do some more investigating, but would appreciate any and all help.

 

[Wombat]

Andy

Check the voltage across the ballast resistor. This should be about 4 to 5 volts. The voltage across the coil should be the remaining 7 to 8 volts of the 12 volt system. If this is OK and the coil makes spark then it is probably good, but if you need to work on the car for long periods with the ignition on it might be an idea to disconnect the coil from the distributor.

Good Luck

 

[RootesRacer]

The coil is going to get hot if you arent running.

Even if a ballast is increased/added the coil will still get hot.

The reason is that when the engine stops, there is a pretty good chance the points will be in the closed condition.

The best solution is to install electronic ignition.
This brings automatic dwell control to the table and the coil is turned off if the engine is not turning.

 

[ozzie alpine]

The best solution is to install electronic ignition.
This brings automatic dwell control to the table and the coil is turned off if the engine is not turning.

Be careful. The instructions for the Ignitor system state that the ignition should not be left switched on for more than a few seconds without the engine running, unless the coil has been disconnected.

 

[Tom H]

Andy,

Your question has already been answered here by others, but just in case you still don't understand let me explain. When the motor is running there is current running through the coil, and that current is turned on and off by the points in the distributor. The points are a switch, a mechanical switch, that turns the current to the coil on and off 4 times each revolution of the distributor (2 times each revolution of the motor) . Depending on the position of the distributor and points when the engine is shut off, the points may be in the On position and current continues to flow through the coil. I think because of the likelyhood of the engine actually stopping near a compression stroke, it is more than likely the points will be in the ON position when stopped. I think, as Ozzie cautioned, that even with an electronic ignition, the switch transistor inside it is probably also likely to be ON when not running but with the key on. Simple fix to pull either one of the low voltage coil wires anytime you need to have the ignition on and car not running.

Tom H

 

[Nickodell]

I did just stumble upon another symptom. I noticed that when everything is hooked up the way I think it is supposed to be (which may or may not be correct...), if I turn the key to the on position, I show a negative draw on the ammeter. Interesting, given that nothing is actually turned on. If I disconnect the lead from the ignition switch to the coil, there is no draw. This would seem to indicate to me some sort of short, either in the coil or distributor. Got to go do some more investigating, but would appreciate any and all help.

If there were a short the ammeter would probably go to the full Discharge ( - ) peg, or there would be a release of Lucas Smoke from somewhere and the ammeter would return to the middle. When you switch the ignition on you are energizing several circuits, for example, the voltage stabilizer, so a small discharge (1 or 2 amps) is normal.

 

[RootesRacer]

Be careful. The instructions for the Ignitor system state that the ignition should not be left switched on for more than a few seconds without the engine running, unless the coil has been disconnected.

If the ignitor you are referring to is pertronics, thats the last electronic ignition I would recommend or run.

Just about any system out there that has a box wont leave the drive transistor on if the engine isnt running. Some even have a current limit which will detect when the coil is saturated, then decrease dwell on the next pass.