Engine stays running only if the key is held in the start position ....

[Cranky]

0.5 is OE..

Thinking 0.5 isn't all that much so how does that equate to the points lasting longer? Yeah, I need to read up on Mopar electrics for sure. Took a correspondence course in electronics while in the military in the early 70's and that's when I found out I might be a bit color blind. The military sure didn't tell me a damn thing about it after taking the Ishihara test.....but then I found out just how bad I was after I had been running an overhead crane for 6 months and the company said that I needed an eye test. Well, I was running pretty good and my boss went to bat for me. Wasn't too many colors in a steel mill anyways and I seeing red, yellow and green wasn't a problem but dirty traffic lights were. Thing, red is always on top and horizontal lights red is on the left but with today's LED lights, it's not a problem. Why am I typing all this?? Damned if I know!

 

[dadsbee]

It (the lowered voltage) is actually to save the coil.. not the points. I may have had a brain fart on the 0.5 but was thinking 5.0 ohms on the upper balllast of a 4 prong, but was pretty sure a single was 0.5. Might be closer to 1 but either way, think of the ballast resister as a control dam along a water way. You send 12 gallons of water at it, but since the channel is restricted you can only force 9 gallons out the other side. Easiest way to explain it, without needing to know the load of the coil..

 

[Cranky]

After checking several resistors with my 55 year old VOM, I didn't see much difference in ohms if any. Used to check spark plug wires and that showed me large differences from solid core vs carbon core wired vs old used ones. Maybe I should try an old plug wire lol

 

[Ranger16]

How is a ballast resistor checked?

I assume you mean how to test if it is failed or not. If you have continuity from one side to the other, it's good.

 

[Daves69]

So you have this ?.....................
With the ballast disconnected (and not jumped) the "start" side should have battery voltage only in the "start" position and nothing in "run". The "run" position should have battery voltage only in the "run" position and nothing in "start".

And your ballast does not show an open?
If your good to there, then it's after that.

The coil and plug wires look aged. Have you checked for arching during cranking in the dark?

Just for grins, if you haven't tried it already, you might disconnect the alternator and wrap the leads to prevent shorting. See if it runs.