Ignition coil input voltage.


New Member
Jul 28, 2019
Hello, this is my first time on this forum, so bare with me and any advice will be greatly appreciated.

I have a 69 Mach 1 Fast Back with the 428CJ power plant and 4 speed Transmission. The issue I am having is the ignition coil see's full battery voltage/alternator output which is around 13.5 volts when engine is running. At idle it drops to around 10.5 volts, but the voltage increases with engine RPM increase. At around 1200-1800 RPM, full battery voltage is present at the coil. With engine off and ignition on, voltage at the coil is round 6.5 volts. The engine will run for about 30 minutes, then begins to stall out and eventually full shut down. While its stumbling, if I open the hood to allow heat dissipation, it eventually clears up. The coil is heating up and starts to shut down due to the heat both internal from too much current and external engine heat.

I have changed out and checked the following:
1) Pink resistor wire, changed out
2) Checked distributor grounds
3) Checked all engine and chassis grounds

I have even bypassed the whole electrical system by using another new resistor wire and attaching it directly from the battery straight to the coil with the same results...I am baffled???
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