Pickup coil testing question

[IROCmenace]

First the back story

Truck is only driven a few days a week.

Got my GMC last October. Bought a Davies coil, cap and rotor kit, Mallory ignition module, Summit wires and new AC plugs.

The old stuff looked to be original 1986 stuff.

2 months later the Mallory module blew. I figured it was a fluke. Bought a BWD and it blew two weeks later.

Did a lot of research. Checked and made sure all my grounds are attached firmly. Have 12Volts at the bat terminal on the cap, grounded off the motor.

I bought a new, not reman Cardone dizzy and put it in, fired right up.

Battery is new as well as the alternator.

It is running right now but I have anxiety about driving it. I now have an extra module just in case.

Now my question.

I tested the pick up in the old dizzy and the resistance was in spec 754Ohms.
I moved the wires all over and it didn't change. I applied vacuum to the advance and it did change about 10-20 ohms but I don't know if that constitutes a "bad" test. Of course if I spin the shaft the resistance goes crazy but always goes back to 754.

Do you think I have found my problem?
TIA

 

[bucket]

Well, it could have just been a couple bad modules in a row, I've seen that before. Not real often, but it has happened.

 

[IROCmenace]

Thanks for the response bucket.

Yeah. I hope so. Do you think the 15-20 ohms the vacuum advance changed the reading constitutes a bad pick up? The books say it should stay steady but it doesn't say the slightest fluctuation is a bad pick up. I am not sure if that slight a fluctuation is a for sure bad pick up or not.

 

[bucket]

Honestly I've never tested one. I've replaced them all on a hunch (with just a known good dizzy) and got lucky I guess. The last one was physically damaged though, so it was obvious.

 

[IROCmenace]

I gotcha. I never messed with one before either. Just replaced the hole dizzy. But on those the pick up had obviously broken down. Yellow dust. Not sure on this. Guess I will just cross my fingers.
I know if the alternator was surging it could kill the modules, but it was replaced before I got the truck. Still has the new sticker on it. But it was remanned.
The factory manual doesn't even say much about the pick up.

Either way a new dizzy is better than the 28/29 year old one.

I will keep up with this and post any findings/results as there is not a lot of definitive answers online that I could find.