47 cad wiring problem

[phil#21543]

 im in the process of restoring a 47 cad.got it back from the paintshop & when i turn the key on,the wire that goes to the coil gets hot & starts to burn.i disconnected the wire & ran it directly from the battery & that wire started to burn.i replaced the points & condenser because they were burnt pretty bad.could it be a short in the distributor? or a bad coil? i would appreciate any help from rookies or pros.   thanks,phil.  

[Doug Houston]

This is a bit unusual, as there is a dead short to ground at the high side of the coil. The first step is to connect another ignition coil in place of the present one and see if the short is gone. I dont recall seeing a short like this, but it would not be impossible either.

Another thing that came to mind when you first asked is that the wire in the armor passing from the ignition switch to feed the coil will have its insulation crumbling as a result of age. there can be a nice big short to ground there. If the coil and that feed wire have ever been handled at all, the insulation can easily be in very poor condition. It can be replaced, and it isnt easy. The switch can be taken apart carefully, and a new wire soldered and the switch replaced. Ive done it a few times. Its a nasty short to have, and that new wire gives a lot of comfort!

[phil #21543]

thanks doug,ill see if that works-phil

[George]

Disconnect the ground side of the coil from the distributor and see what happens, if anything. If nothing happens ground the coil to the body and not the distributor. If the problem then occurs at least you know it is either the coil or the live feed. Connect a live direct from the battery, to the coil, if that gets hot it definately is the coil unit. If it doesnt, the problem is likely the feed from the switch.

[phil#21543]

george, tried another coil & it works fine. its good to know about the other ways to check the system.if i didnt have another coil i would have found the problem the way you suggested.thanks for the info.  phil