Coil Confusion

When a coil fails it most often a turn to turn short in a winding. The short happens when the enamel insulation burns on the magnet wire. A turn to turn short cannot be determined with an Ohm meter because the change in resistance is small compared to the tolerance of resistance due to other factors including turn count. Typically the failed indication is a weak red spark.

While the oil helps cool and insulate, hot spots carbonize the oil, that is bad because that conducts. A coil can can only get out so much heat. A chrome plate, heavily painted, or fancy stickers hold heat in.

Pishta is correct, use a stock coil. I go further, use correct ballast too. While ignition energy increases with current squared, too much will burn out the transistor in the mopar box. Transistors have a weakness when used at high temperature, current and voltage. The transistor is rated with perhaps little excess for stock application. Transistors typically short when failed. Low Ohms to ground at the disconnected (-) wire that goes to coil, will identify. Do check with ignition off. An open transistor will not pull coil (-) to ground when ignition is on.

If you really want to diagnose ignitions, a current probe and scope provides more meaningful information than a voltmeter. The voltmeter does not measure the peak current, it give an average voltage for the pulsating signal that also varies with RPM.