The Stovebolt Site Forums The Shop Area The Electrical Bay My coil blew up

The coil on my 54 blew the top off, it is new only drove the truck about 8 miles. Put an old one on from my 55 2 ton. So far it is OK. The 54 is 12 volts. Any ideas why?

If it's[or was] a 12 volt coil than I would think that it was a bad one from the jump.
Alot of stuff isn't made as good as it was back in my day,mass production and overseas just don't care.

Pete

Could it be that the 12v coil that blew up was meant to work with a ballast resistor, or could it have been a 12v coil made for electronic ignition?

Both these coil types will have a low resistance on the primary side which will cause high current and overheating if they're used with an ordinary points setup.

Stuart.

no, ballast resistor is to keep the points from burning out. full voltage to either would work fin, however if there is a bad section of insulation in the winding, add vibration and you let out the magic smoke.

Coils meant to be used with an external ballast resistor have a lower resistance than a standard 12V coil, and would be unlikely to live too long without the ballast resistor in circuit under normal running.

Typical resistance of coils intended for constant energy electronic ignition is 1.5 ohms or less. that equals 8+ amps across the closed points. I can't see the points dealing with that kind of current for long unless the coil overheats and burns out first.

Stuart.