How to fix a HEI Distributor Pickup Magnet Polarity Issue

I first ran across this magnet polarity issue 2 years ago on the Buick 455 Powered 1985 C20 Chevrolet Suburban. It took me almost 6 months to work this issue out due to the lack of information available on the internet and personal experience. When I ran across it again, I knew it was time for a video, since many people must be having the same issue with their HEI Pickup Coils.

[@atlas869]

because of this video i changed the pickup coil in my motorhome and it hasn't ran that good in years!! thx so much for saying the missing at idle!!! what a difference!!

[@kimdearrington258]

Thank you for pointing out this issue, I'm certain that hundreds of people have had this problem and pulled their hair out trying to figure out what was wrong.

[@djrowe10]

I am one of them. My machine shop owner recommended this video. 👍

[@JrsGaragePa]

Good info to know. I never dreamed that would be an issue, always assumed they were all the same

[@67L-88]

Years ago and years before that I bought several new pick-up coils made by Accel in the dollar bin at a swap meet. So we install one in an SBC it ran like crap and we noticed that two cylinders were running way retarded as the exhaust manifold would glow red. Anyway, we just popped in a spare distributor and all was well. We never did look at the distributor but we always said buy junk at the swap meet and this is what you get. So now I wonder if that was really a non-chevy application coil. Interesting food for thought...

[@racerx7319]

NEVER HEARD OF THAT BEFORE . THANKS FOR THE INFO.

[@mr.roddersneighborhood2740]

No Problem... now you know what to look for.

[@alantrimble2881]

If the polarity magnet polarity is backwards, just flip the polarity of the pickup coil output wires.

[@lesliemclean4381]

That'll work as well?

[@bossbuick8615]

thank you it's true you learn something new every day and this is a new one for me keep up the good work

[@brracing7861]

The HEI GM Ignition has What is called expanding Dwell. At idle Dwell time is 4-8 degrees by reference of crankshaft rotation. At 3000-4000 rpm crank speed the Dwell expands to 40 -50 degrees Its Varying the Ignition coil Saturation time

[@brracing7861]

What takes place to expand Dwell time is the AC Signal is Rectified and fed into an Op Amp or Operatial Amplifier. Gate Transistor circuits before being Netwirked connected to the Darlington Transistor.

[@gordonborsboom7460]

You had me there for sec. Good one

[@dondotterer24]

Thanks for the video. Very important helping people

[@fsj197811]

Thanks for sharing and I hope to see some video of you running Lemons. 🙂

[@brracing7861]

The Pickup coil in all MSD , Chrysler, Ford, GM HEI, and Early 1963 Pontiac And Corvette Transistor Electronic Ignition is an AC Signal generator. It creates A Saw Tooth AC Signal. There is Phasing to that signal correct. Negative polarization and Positive Polarization.

[@tombrown879]

It would be interesting to test what the polarity is on a Chevrolet. I'm leaning towards this may be solely a manufacturing issue. Has shaft under the distributor cares not from what side it is being spun from you could literally just spin the shaft from the bottom in the center as long as it's turning the correct way. And as for the phasing as long as the magnet bolts in correctly the phasing should be correct. I believe that they are just not testing the magnet or not caring about testing the magnet before gluing it to the metal ring in the manufacturing process.

[@tombrown879]

If it is a type of electromagnet. Maybe you could just swap the polarity of the wires going into the magnet assembly.

[@alantrimble2881]

@@tombrown879 It's not an electromagnet. It's a permanent magnet surrounded by a coil of wire. When the iron pole piece on the distributor shaft spins, a current is induced in the coil of wire. The module contains an analog to digital converter that converts the current/voltage signal to a digital signal. Also within the module is an amplifier circuit and a switching transistor. The amplified digital signal is used to control the transistor. The transistor takes the place of mechanical points. That is, it cycles the negative terminal of the coil to ground in order to fire the coil.

[@dondotterer24]

I always use a good used distributor and adjust the end play with factory parts or ones from performance Distributors.

[@brracing7861]

I have Electronics background that started Professional 1987 year. Hand picked out of my Highschool for an local electronics tech job through College.

[@brracing7861]

It's also a basic Tachometer RPM Counter the Op Anp.

[@brracing7861]

Hexidecimal counter. Same is is used in our Vintage Musclecar dashboard, Console, and Hood mounted Tachometer a Hexi decimal TTL Counter with special RF filters

[@brracing7861]

Inside of that GM HEI module is A Darlington Transistor.. PNP Based Transistor

[@brracing7861]

Mumble Jumbo to all I know but that is what taking place Taught Electronics Engineering all. Became a Mechanic been valuable knowledge and skills I posses no other Mechanics alive have but myself

[@brracing7861]

To Veify AC Signal phasing correct you need an Oscilloscope or its trial and error without

[@brracing7861]

Also inside the GM HEI Module is a basic computer, bit really because you need a Quarts or Nuclear Atomuc Isotopes clock signal generator oscillator to quality as a True Computer.

[@dondotterer24]

Yes I weld the slots up for what I want.

[@brracing7861]

Also the Chineese Cheet skimp out on the Original design Parameters criteria set by AC DELCO REMY ELECTRONICS ENGINERS. Original Functional HEI Module is Gold and Diamonda

[@firstrespondergarage]

Um, more on that car please looks interesting.

[@willdy]

I think you could've swapped the coil with a reverse polarity model to also fix the problem rather than swapping the magnets. Chevy =red, yellow & black wires while reverse polarity Buick =red, white & black wires

[@robertsoutherland137]

U know that dimple on the gear has to line up with rotor or it will be off phase, it can go on 2 ways

[@patrickbooth2329]

This may be my problem i bought brand new distributor from summit i never thought it would be a turd . so i got another new one same problem . new different spark plug wires set valves new spark plugs . still vacum 10 and with lots of advance timming runs better but still $hitty . so after 2 distributers now its time to look inside .oh i forgot to mention this has 2 4 barrels and 468 cub

[@mopster1913]

Can I reuse my intake manifold gasket on my buick 350?

[@mr.roddersneighborhood2740]

Generally the steel pan gasket can be cleaned and reused. The china rail gaskets normally cannot be reused and require purchase of a second gasket to get new china rail gaskets. If you have the china rail gaskets on hand... reuse the steel valley pan gasket.

[@dondotterer24]

Is that the mixed up carb? Does the power enrichment work with the 6 tube top?

[@mr.roddersneighborhood2740]

No that’s not the same carb. That’s a 75 model carb with the weird 3rd metering rod.

[@dondotterer24]

@@mr.roddersneighborhood2740 OK just wondering. Never did that before.

[@dondotterer24]

@@mr.roddersneighborhood2740 scammers are your channel like others

[@davidrowland2354]

Would this be a thing on a 83 chevy g30

[@mr.roddersneighborhood2740]

It can be a thing on any HEI equipped engine.

[@daniellachance9730]

Great vid!

[@mr.roddersneighborhood2740]

Thanks!

[@forthwithtx5852]

Interesting problem.

[@gordonborsboom7460]

Have you ever considered using a factory ESC module and knock sensor version of the HEI with the multi pin module? Possibly would give knock retard to an older motor. Would such a system (Chevy) work on BOP application? Just a thought.

[@mr.roddersneighborhood2740]

There is a guy who was making small body HEI’s from the Chevrolet to fit a BOP application. I do not even know if he is still around. It would work I believe

[@brracing7861]

There was an Article Writen in High Peformance Pontiac magazine all about Electronic basic Theory of GM HEI Wriitten by Don Kief I recall 1994 Year. I have that HPP Issue put away yet, a Lucerene Blue 1970-1/2 Trans Am Grace's the Magazine cover I know. I get to 500 subs I will have my community page able to post Vintage articles and photos of my past and present just Like I used to do on the Internet Car Forums Something that has sucked about You Tube must have 500 subs to post pictures

[@Greaseland]

I'm available to drive the Lemons car.

[@mr.roddersneighborhood2740]

We are full up on drivers... That's for sure! I'll do an episode on the Lemons Car. People are asking, so I'll deliver.

[@unclesquirrel6951]

Personally I blame squirrels

[@SweatyFatGuy]

Its still the woodchucks directing the squirrels... commisar woodchucks.

[@unclesquirrel6951]

@@SweatyFatGuy 😁