Hey all,
I have a problem I have been chasing for a little while now. 67 400, with a Mallory Unilite electronic distributor, and old school style Mallory 29150 coil. Car used to start without any issues, but over the last year it has been getting harder and harder to start. I checked the voltage and it was 12.8 at the battery, 12.8 at the rear of the alternator, and 3.8 at the coil with the key on. And when I crank the car, the coil drops to 0.0. The car will start if I crank it for several seconds to load the cylinders with fuel then let off the key and "BAM" like a 12 gauge through the exhaust it pops then fires up. The resistance in the coil measured 1.7 ohms which is normal for that type of coil. Is it possible that there is an issue with the original resistance wire? I am completely stumped.

Not sure about the resistor/wire...but that was my first guess.

I'd replace/jump that wire to see if it cranks properly. Then go from there...

Is the Mallory Unilite electronic distributor supposed to get a full 12v or 8v that would come through the resistor wire?

Any changes made to the starter wiring? Are the starter wires wired to the correct "S" and "R" Terminals?

Has the ignition switch ever been changed?

You should get a full 12v while cranking from the purple wire and a constant 8 volts from the pink resistor wire. So as BronzeBird said try a direct wire from the battery to the coil and see what happens first..

So I located the problem. The Wire that runs to the coil (+) from the starter solenoid was broken near the rear of the passenger side head. I found the wire, hooked up my electrical tester to it, and sure enough it lit up when the starter cranked. m going to replace that whole wire and see if the car starts easier....fingers crossed that's all it was. I appreciate the responses!