Posted by Sherman in Idaho [108.162.246.24] on Saturday, October 01, 2016 at 19:42:06 :
Decided to add a little tach to the '62 1-ton. Early slant 6 with mechanical ignition. Left the ignition on so I could listen to the radio, and after a while, the battery was dead. Coil was hot, so obviously the points were closed and I shouldn't have left the key in the on position for that long (No "accessory" position back then. Okay, turned off the switch, hooked the charger up to the battery, measured the resistance of the coil primary and secondary to see that the coil wasn't burned out, and got back to work on other things.
After the battery seemed charged and the tach was hooked up to the coil (but its ground had come loose), I turned the ignition on and the wire between the coil and the distributor promptly burned up. Hot wire to the coil wasn't even warm. Ballast resistor wasn't warm. skinny little tach wire to the coil wasn't warm. But the one foot of wire from coil to dist was burned to bare copper.
Any idea what could have happened? Looks like I might have to pull the distributor to change that wire, too. Have not dug up the wiring diagram, but as I recall it was bonehead simple.
If the coil had failed short from the previous overheating, the hot wire to the coil should have carried just as much current as the wire from the coil to the distributor, and it should have melted as well, or at least the ballast resistor should have gotten hot. Any guess would be appreciated. Is there some tricky thing in there that I don't know about?
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