C-1 Coil overheating

[Ted K.]

My recently purchased 56 Vette stops running after 15-20 minutes. Cause is lack of spark. Discovered that coil is very hot at that time and there is some oil leaking out of the top it. Replaced coil. New coil gets hot also, hotter than other coils I am familiar with. It appears to be hooked up properly, ignition wire to ceramic resistor, resistor to + side of coil, - side of coil to distributor. + side of coil is shared with another wire that goes into wire harness. Engine won't start with this wire disconnected from coil, starts right up when connected.
Coil gets so hot I'm sure its life will be very short. What's the problem? Are there different resistors I should try???
Thanks

[Jim T.]

Re: C-1 Coil overheating

The other wire going to the coil could be a source of 12 volts after you 56 starts. With this other wire disconnected and the car not starting this wire in the wiring harness is the the wire from the starter solenoid to the coil that has full 12 volts when the ignition is turned to the start position. Using a temp jump wire connected between the coil and this wire that can be separated safely after the car starts, use a test light and confirm that there is still 12 volts supplied by the wire coming from the wiring harness. With the wire disconnected see if the coil is still getting hot. If the wire still has 12 volts with the car running, the wire going from the ignition switch to the starter solenoid could be on the wrong terminal on the back of the ignition switch. I had a 55 Chevy a very long time ago, but I don't know how the back of your 56's ignition switch is configured and for sure how my ole 55 was configured. The ceramic resistors job is to reduce 12 volts to about 7 volts to keep the points from burning. There are persons that post on this board that have more experience of your problem.

[Jim T.]

Re: C-1 Coil overheating

The other wire going to the coil could be a source of 12 volts after you 56 starts. With this other wire disconnected and the car not starting this wire in the wiring harness is the the wire from the starter solenoid to the coil that has full 12 volts when the ignition is turned to the start position. Using a temp jump wire connected between the coil and this wire that can be separated safely after the car starts, use a test light and confirm that there is still 12 volts supplied by the wire coming from the wiring harness. With the wire disconnected see if the coil is still getting hot. If the wire still has 12 volts with the car running, the wire going from the ignition switch to the starter solenoid could be on the wrong terminal on the back of the ignition switch. I had a 55 Chevy a very long time ago, but I don't know how the back of your 56's ignition switch is configured and for sure how my ole 55 was configured. The ceramic resistors job is to reduce 12 volts to about 7 volts to keep the points from burning. There are persons that post on this board that have more experience of your problem.

[Dave Suesz]

Hot coil

You should check the resistance of the ballast resistor. It could be defective, damaged, or simply the wrong one. Dunno about the 56, but a 55 coil is well over a hundred bucks. Excessive voltage is also bad for the points. The 55 delivers more voltage to the points, for greater ignition power, at the expense of point life. The passenger car used lower power, for reliabilty, if I recall correctly.

[Dave Suesz]

Hot coil

You should check the resistance of the ballast resistor. It could be defective, damaged, or simply the wrong one. Dunno about the 56, but a 55 coil is well over a hundred bucks. Excessive voltage is also bad for the points. The 55 delivers more voltage to the points, for greater ignition power, at the expense of point life. The passenger car used lower power, for reliabilty, if I recall correctly.