72 TA : New Project

[njsteve]

Interesting! I will do some more experimenting tomorrow and see what the results are.

[njsteve]

Today's experiment involved taking the original resistor wire lead from the original burned factory harness and connecting it between the pos terminal on the coil and the pos harness leads to see if the voltage would be reduced. I would note that the original resistor wire does feel different than the alleged resistor wire that is in the repro harness. The original wire is a much stiffer, silver colored wire with a rubberized jacketing and, not copper wire with regular colored insulation as in the repro harness.

With the car running, the voltage varied between 10.5 to 11 volts depending upon idle speed. With the car off but the key in the run position, it shows 12 volts (as predicted by member John Brown). Very interesting result since it indicates that the original factory resistor wire doesn't cut the voltage down to the recommended 9 volts.

I then took an old ballast resistor, (actually the one from the original cobbled together and toasted harness with the aftermarket electronic ignition) and connected that between the pos coil terminal and the repro harness pos leads. The result was 9 volts when the engine was running and 12 volts with the engine off and the key in the run position. Though not stock, it brings the car right into spec for points ignition running voltage.

I then removed the ballast resistor and hooked the repro harness back up as it was originally and it read 14.3 volts with the car at high idle. When not running but key in run position it read 12.4 volts.

The battery by the way read 12.8 volts with the car off.
When running and the alternator charging, the battery read 14.3 volts, the same voltage as the alternator output. If you shut off the car, unplug the alternator and restart the car the pos coil voltage reads 12.4 volts.

So the inevitable conclusion is that there is no resistor wire in the repro harness and that whatever voltage the alternator is putting out is the voltage that is going to the pos lead on the coil, resulting in fried points.

I will update this electrical mystery after I talk to American Autowire and M&H on Monday.