Assuming all the wiring is correct, with the key in the "on" position and the engine NOT running you should see battery voltage on the coil + (and on the coil -) when the points are open. The lower voltage (usually around 8 or 9 volts) will be seen on the coil + and zero volts on the coil - when the points are closed.
If the engine is running an analog voltmeter attached between coil + and ground will give an average of the 8 or 9 volts and the 13 or so volts that the alternator will be providing to the electrical system. If the engine is running a digital voltmeter attached between coil + and ground will typically bounce around all over the place.
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My Pontiac is a '57 GMC with its original 347" Pontiac V8 and dual-range Hydra-Matic.
Last edited by Bill Hanlon; 09-06-2020 at 11:57 PM.
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