HEI Conversion. Weak pickup coil?

Hello all. I read up on the GM HEI swap. I have installed my system leaving the mopar system as backup. The engine runs on the mopar system but the magnetic trigger will not trigger the HEI. I can trigger the HEI system with a GM pickup coil. Had anyone experienced a weak mopar magnetic trigger? I set the gap on the mopar trigger and no help.

if i'm not mistaken, the HEI needs a constant 12 volts to run.
are you feeding the coil from the ballast resistor ?
that would cut the voltage down.

I have converted my '73 Dart to a HEI-module ignition (and more).
Uses a stock LeanBurn distributor to signal the HEI without issues.
The HEI module gets full battery power over a relay.

you may have a poor connection in the pickup leads/pickup coil. I would check the connections/terminals & if no go get another pickup.

I ran a wire from the battery for testing...I will try another pick-up...didn't know if the PU was a frequent maintenance item...
Thx guys!

Generally they are very trouble free, but once in a blue moon...

Just did one on an 81 Dodge truck and works great, make sure the module is has a good ground and the 12 volt wire that feeds the module should feed the + side on the coil

The system works by substituting a GM pickup coil and spinning the GM distributor by hand.

The new pu coil will be here today. Hope it's running by tonight!

Thanks all!!!
Milan

Sounds like you found it

I think you nailed it, that's probably the issue.

I've experienced intermittent, weak, and open circuit mopar pickup coils.

I really like the mopar distributor/hei module + better coil (latest favorite is the TFI) and no ballast on street oriented stuff
where you don't need extra bells and whistles.

Hey all, so I got the car running with the HEI conversion. What a difference starting up!! I have yet to drive it through. When installing the new pu coil I realized that I had to set the gap on the new PU coil super tight to get a signal to fire the coil while cranking. I suspect that if I had tightened up the original pu coil gap it might have worked fine. I guess the mopar pickup coil is at the lower end of the trigger threshold for a HEI module. Anyhow, I wanted to share my observations.
Best ,
Milan

OE gap is .008" & you want that on the tightest tooth (they can vary) & as you said if the gap was high it certainly could have caused your dilemma. Just me I'd swap it back for a day to find out (I'd wanna know). But you are up & running & that's the main thing.

Any advantage to trying to make all the vanes on the rotor equal?
I wondered what the variance between the tallest/shortest would be...

May be touching the tip of the tallest with a mill file and then seeing where the next tallest was.

Would the resulting change in the width of the rotor vane tip affect anything???


Joe

& vac adv drastically changes (increases) the gap. If the gap is too big I could see where vac adv in use could cause a miss. Our South American member Nacho (who ain't posted in awhile as he has been too busy sunning himself on the beaches down there) reworked the plate to get that variance down to near nothing. Joe I would think getting the vanes equal would let you set the gap to the bare minimum. (I'm gonna rework the plate, just ain't got around to it yet). Maybe not an earthshattering (timing) difference but every bit counts & it keeps a person in the correct mindset of always searching for that edge (helps keep the furds/chebbies in their place).

Years ago, several aftermarket companies used to sell ball bearing breaker plates, where the advance plate rotated around a center point, not from a point off to the side like many of the factory ones were. Probably worth looking into.

I noticed that also caused a problem with keeping dwell within specs when I was doing tune ups 50 years ago.