Ignition problem, could use some insight.

[BUBBAS IGNITION]

Hopefully when you get the charging system working it will be fixed....

I stayed out of this discussion from the start up as i just felt we didnt have enough information. But watching it every day i think it came out ok anyway.
However lets discuss the situation and what was said.

Customer said :

What I've got is a '47 59ab motor with the stock distributor. I'm running the one piece crab cap, a big old square Mallory coil, and I'm running on 12v neg ground. The car has been on the road like this for about 7-8 years.

You always need to give the car credit , if it ran ok for 7 years that rules out quite a bit. Coil, ballast and ignition seems to be very functional.

Yesterday I had it die on me on the highway. I have two problems that I don't know if they are related. It just shut off at 70 mph. When I costed over I saw it threw the fan belt off, but not the water pump/alternator belt, and I don't think it caused any other damage. It didn't get hot because I was on the highway.

Another bit of info, the car shut off and threw a belt off the front of the engine. Now after hearing more it could very be that the alternator caused this entire problem, maybe a short to ground causing the ignition to just quit etc.???


After getting it home I tried a test light on the coil, I don't show any juice on either of the terminals. I have a big mallory ballast resistor on the firewall, one wire goes to the stock ignition switch, the other obviously goes to the + coil terminal. With the key on I have power going into the ballast but the test light isn't even dim on the other side of the ballast. I thought I had it nailed down, but I switched in another new ballast from my dad's model a with the same setup and I still just get a ballast that is warm to touch and only shows power on one terminal. I'm at a loss now and welcome suggestions, thanks for reading.

As others stated , you really got to know your test light and the voltages it will light under. Also the use of a test lamp is positional , meaning the position of the distributor makes all the differences in the world with test light testing.
Ex: If the points are closed ( grounded) then current will flow making the voltage drop high in the ignition circuit causing a very dim test light based on voltage drop across the components.
Makes it even tougher to diagnose.....
staying tuned hoping this one is fixed ......with a new alternator etc ????