ignition problem on Case VAC

[Ken(WI)]

My 92 year old father has a late 40s VAC, 6v system, with a problem. He has burned out 3 coils. After the motor starts, with a new coil, it runs for only a couple of minutes before it cooks the new coil. Does anyone have an idea of what might be the cause of this?

 

[Anonymous-0]

the vac is positive ground ,, maybe not your problem ,, but if the battery has been swapped doubloe check

 

[old]

A lot of those old tractor had a ballast resister in line with the coil and with out it you will cook a coil. Of course he could also be having the trouble of buy a coil form the land of almost right. I would get a new coil from a good auto parts store.

 

[Christopher Mikesell]

Wiring the coil backwards (swapping "+" and "-") should not cause your problem. This would only cause a weak spark. It sounds like you either have too much voltage to the coil, too much current through the coil, or have too little air circulation around the coil.
Too much voltage to the coil would cause too much current to travel through the coil. This causes heating which can cause the internal coils to break (or de-solder from the lugs), and can cause insulation breakdown which can cause the internal coils to short. Either instance constitutes failure. This would be caused by using a 12V battery in the ignition circuit. The solution is to either remove the 12v battery or to add a ballast resistor to the circuit which connects the battery to the coil.
Too much current to the coil (with a 6V battery) can be another reason for coil failure. This condition can be caused by insufficient points gap, a badly worn distributor cam, or a partially shorted capacitor (condenser). This causes overheating failure as before.
It is also pissible to have the coil mounted in a position which will prevent air circulation and cause it to overheat. In a VAC, the coil was originally mounted to a bracket on top of the valve cover. It is also common for people to move it to the side of the engine. The coil should not be packed into a tight spot (like behind the dash panel).