[Half-Inch Stud]

My project is to Remote the Module to the Firewall, from the Hot Dizzy/Engine. So I had to sort-out Reluctor wire Immunity to interference.

[Bill Hanlon]

Not the same ignition or vehicle, but I had a friend make a mounting plate for my '52 GMC six distributor. I put a mid-70's Chrysler slant six pickup and reluctor wheel in the distributor and hid a GM HEI module and a heat sink inside a gutted voltage regulator box on the firewall. The HEI module runs a MSD 8202 Blaster 2 coil. To connect the mag pickup to the HEI I used about 6 feet of shielded #22 twisted pair wire I found on eBay. It has been working well since installation 6+ years and 30,000+ miles ago.

My initial testing used 10 feet of that twisted pair wire, just to present a "worst case" environment.

Don't forget to ground just one end of the shield. I chose the HEI end because the connection was much easier to make.

[Half-Inch Stud]

Check all my 4-pin Modules and a couple 7-pin modules. They all work: Triggering on "Make". All showed Dwell Expansion about 7* at 600 rpm to 22-24* by 2500 rpm. Motorola M3334 Packaged IC evident in 1-module with loose lid.

A 7 pin module goes 7* - 22* - 17* which seems strange.

Observation is how the Module Grounds through the mount screws, which is very important.
1 screw boss may show a Steel cap welded to a steel midplate. Best gronud.

Brass sleeves pressed-in and they touch the Aluminum Base: good ground.

Brass sleeves that "rivet" at both ende: LOOSE as a goose, a definite failure mode for Grounding even when the 2 screws tightened.

Steel roll-pin sleeves; possibly poor ground. Both 7-pin modules have such.

Voltages present at Reluctor terminals:
1.30-1.36V except the GM 990 shows 1.86V. White being 0.01Volt above Green (no reluctor connected).
7-pin modules show 1.0Volt for white 0 Volt for Green.

[Schurkey]

Interesting. Thanks for that.

Re: voltage at the pickup coil connections

GM uses a bias-voltage supplied to the pickup coil as part of the dwell-variation and/or current-limiting circuitry. This bias voltage is variable,

I had NO idea about this until I read through about a dozen pages of postings on a motorcycle forum--the overall intent was to replace two (4-cylinder) or three (six cylinder) expensive OEM electronic ignition amplifiers with two or three readily-available HEI modules and "distributorless" dual-spark-terminal ignition coils; and there were some problems especially at cranking RPM. It's been years--I think one "solution" was to add a resistor and external power supply to the pickup coil circuit and provide additional bias voltage during cranking. I'd have to dig up that thread and review to be certain.

[Formulas]

Sooo what's the rub ? I hear the module doesn't like reversed polarity I hear the coil wire color needs to match polarity.

What is the average enthusiast going to experience with mismatched components,

I have been running for YEARS a Pontiac pole piece an accell module and yellow wire coil,
It's not supposed to work right, right? What am I missing if anything?

Either the sky is falling or not,

[Schurkey]

First off, ELECTRICAL polarity and MAGNETIC polarity are different things. All the HEI parts have the same effective electrical polarity, but there's differences in the MAGNETIC polarity of pickup coils and ignition coils. The ignition module doesn't like reversed electrical polarity, but it has no way to sense magnetic polarity, magnetic polarity has no effect on the module itself.

I don't know why the ignition coil magnetic polarity needs to match the pickup coil magnetic polarity, I just know that GM went to considerable trouble to make both polarity versions of the ignition coil, and has their parts-books set up to assure matched sets. Yellow pickup coil > red/yellow ignition coil; Blue/black, or clear/no color code pickup coil > red/white ignition coil.

The pickup coil polarity is important so that electro-magnetic interference (EMI )(likely from the starter motor, but that's not guaranteed) doesn't create a false signal that triggers the module. Pickup coils are essentially an antenna for electromagnetic radiation. The pickup coils are set up so that the EMI produces a positive-going signal instead of a negative-going signal. The module ignores the positive-going signal. If the EMI produced a negative-going pulse through the pickup coil, the module would trigger a spark.

With one substantial exception, all the engine families that have the starter motor on the right side use one magnetic polarity, all the engine families that have the starter motor on the left side use reversed-magnetic-polarity. And that includes Oldsmobile, which generally has the starter motor on the left, and uses the Black/Blue pickup coil and the Red/White ignition coil. The Olds Toronado has the starter on the other side, and uses the Yellow pickup coil, and the Red/Yellow ignition coil. This is why I think the RFI interference they're trying to filter out comes from engaging the starter motor.

The big exception is Buick: Has the starter on the same side as Chevy, Caddy, and Olds Toro--but uses the Black/Blue pickup coil and Red/White ignition coil. I don't know why Buick is different.

The module itself is the same no matter which pickup coil or ignition coil polarity you use. No difference.

Use the wrong parts, you maybe have occasional problems with false triggers of the module, leading to sparks at random times which could lead to backfires, or over-advanced "timing" trying to spin the crankshaft backwards especially when cranking the engine. I suspect GM took the trouble to deal with magnetic polarity in order to prevent broken starter housings.

[Formulas]

Well I have been running mismatched parts longer than I can remember without any outward obvious problems no broken starters no kickbacks no burnt coils / caps nothing but a smooth running engine.

That's why if there's better performance by matched parts it would be nice to know what that's like, what a person would gain but it appears to be a moot point

[Schurkey]

Originally Posted by Formulas

Well I have been running mismatched parts longer than I can remember without any outward obvious problems no broken starters no kickbacks nothing but a smooth running engine.

That's why if there's better performance by matched parts it would be nice to know what that's like, what a person would gain but it appears to be a moot point

You may have "mismatched" parts, but your pickup coil is correct for the application. I think that's the most important.

[Kenth]

This may be of some interest:

[george kujanski]

Years ago I said bunk on the starter motor noise relationship relative to HEI and still do. You have high voltage sparking right near a module inside the cap and i am to believe a starter motor located away from the HEI is going to bother the module? Whatever caused GM to state that probably was debunked later but no one wanted to change the status quo. Never seen that before in the corporate world right?

I suspect the system voltage drop caused by loading on the starter and cable length, etc. caused the module to misfire.. the whole thing was probably started (no pun) by a fresh engineering grad getting his feet wet in the biz.

I don't believe it and I've purposely swapped ignition coils in my HEI (they DO have different magnetic polarity BTW) and there has been no change.

I stand by what I said.

george

[Half-Inch Stud]

Originally Posted by Kenth

This may be of some interest:

Nope, that first figure is of no interest. The 2nd figure is useful.

George, George, George; you would be correct from my take on the MAGNETIC system. Even the Alternator in aluminum case would be a srtong open pole compared to the Starter (aluminum nose allows mag field to fringe out. So my take on reluctor sensitivity to magnetic variation can be verified by the Weller Gun proximity triggering to not triggering when pulled away (credit Schurkey for the solder gun triggering method).

To summarize: I observe Voltage polarity to be the same for 4-pin and 7-pin modules: they both trigger on "Make". whereas HEI articles say 4 & 7 are opposite voltage triggering. I will move on with what is observed, and share for others to investigate. For those that say gobblygook to all that jazz, no worries if their HEI works. However when an HEI seems flakey, who you gonna call.

[Ben M.]

Originally Posted by Schurkey

I don't know why Buick is different.

Distributor is on the front of the engine vs. the back like the others is the only noticeable difference.

Bias voltage being variable likely has to do with how easily triggered the system is at low vs. high RPM and the location on the B-H curve the system starts out at per pulse vs. RPM (note: this is an educated guess based on what I've done on pulsed systems I've designed).

Originally Posted by george kujanski

I stand by what I said.

I agree with everything you say now and have been saying. I use saturable reactors and high voltage charging inductors not unlike an automotive spark system in work and have for 20 years. This is why I have said I want to see voltage waveforms of everything to get a real idea of what is going on vs. what people say is happening. I 100% agree with Schurkey that GM went out of their way to specify the different pickup coils and ignition coils so obviously there was a reason, but I don't know what reason that was and I'm not 100% convinced on the story of the location of starter motor as that's many feet away and a simple DC motor - and as Schurkey pointed out doesn't hold true for FWD Olds and Buick.

Such a shame we don't have a line on anyone who worked in the ignition design on these cars, just some engineering notes or an interview or two would have gone a long way to answer these questions. And in agreement with George I'm sure a part of it is "this was the thing that stopped random hot start\stall\misfire issues so we shipped it as-is."

[george kujanski]

If someone had told me that I was to design an ignition system with the logic buried under a cap-in-coil design i would have told them that would never work well with all the EMI (ElectroMagnetic Interference) under the cap Regardless of where the starter is.

Same is true for an electric motor in the gas tank that has gasoline running thru it keeping it cool................

But what do I know?

george

[Kenth]

Seldom heard of:

[Shiny]

Thank you all for sharing your insight into this stuff. Very educational.

Originally Posted by george kujanski

....But what do I know?

george

Way too much! My guess is you know exactly why they got away with it !

Originally Posted by Ben M.

...

I 100% agree with Schurkey that GM went out of their way to specify the different pickup coils and ignition coils so obviously there was a reason, but I don't know what reason that was and I'm not 100% convinced on the story of the location of starter motor...

Such a shame we don't have a line on anyone who worked in the ignition design on these cars, just some engineering notes or an interview or two would have gone a long way to answer these questions. And in agreement with George I'm sure a part of it is "this was the thing that stopped random hot start\stall\misfire issues so we shipped it as-is."

LOL... you have all obviously worked in corporate R&D orgs. "Ship-it" was a standing joke everywhere I worked whenever a program or engineering manager forced acceptance of known deficiencies and/or issues.

Originally Posted by george kujanski

....Whatever caused GM to state that probably was debunked later but no one wanted to change the status quo. Never seen that before in the corporate world right?

george

Right!

Originally Posted by Kenth

This may be of some interest:

Originally Posted by Half-Inch Stud

Nope, that first figure is of no interest. The 2nd figure is useful.....

That document does not feel like an engineering doc. What is it?

"The purpose of these various pick-up windings is to hold in the suppression of the radio interference generated by the HEI system."

Huh?

[johnta1]

Most customers would be very pissed if they couldn't listen to their radio.

Points made a lot of interference and had the condenser on the coil to help alleviate it. (same with heater fan and alternator sometimes)

They probably had RF that would show in the radio reception under certain conditions. So the coil windings may have been reversed to counteract the RF being picked up. (cheaper than a lot of shielding on distributor or coil?)

[Half-Inch Stud]

"Ship it" was a good joke indeed, but not the attitude where i worked.

As said: The induced voltages, and time-varied Mag-fields under the HEI cap are substantial enough to be a full design-optimized.

I too don't see the Alternator nor Starter Mag fields getting into the design space, nor 8 plug wires jumping high energy neither.

Overall, i started a Thread for heads-up on Reluctor Voltage Polarity. The best I can summarized to date is: The 4-pin and 7- pin modules BOTH trigger on pole-piece "Make". All my reluctors turn-out to be setup to do such.

Such elf-investigated guidance appears to go against some articles which say the 4- pin Modules trigger on the voltage decline whereas the 7-8 pin modules trigger on the voltage rise. My inspection shows they all trigger on the voltage decline.

a proper reluctor ppears to show positive voltage rise upon MAKE, and negative voltage on Break, making a triangle wave first positive then negative and back to zero. Only one 0 crossing and its a doozy.

[Ben M.]

Originally Posted by Half-Inch Stud

Such elf-investigated guidance appears to go against some articles which say the 4- pin Modules trigger on the voltage decline whereas the 7-8 pin modules trigger on the voltage rise. My inspection shows they all trigger on the voltage decline.

You can always check out what the MC3334 IC looks like from the specifications document...

[Sun Tuned]

Kenth was posting some rather old Delco Service Bulletins. Rather informative .

[Schurkey]

Originally Posted by Sun Tuned

Kenth was posting some rather old Delco Service Bulletins. Rather informative .

The whole works was part of a .pdf hosted on the internet by FeidlerH (spelling?) but the link I had went dead years ago.

It came from a Delco service manual, with some notes taken at an HEI service training conference. Some of the notes he posted were hand-written. Eventually, I bought a copy of that HEI training manual on eBay.

Delco talked about problems at cranking speed. They didn't go into detail. Until someone proves different, I'm going with the hypothesis that it has to do with EMP from massive instantaneous current draw when the solenoid pops the drive into position against the ring gear, and first engages the starter motor For a split-second, until the starter motor begins turning, it's essentially a dead short on 4-gauge cables. Ever see a car with a shorted starter motor, when someone turns the key to "Crank"? There's so much current flow through the starter cables that they become electromagnets, they'll slap up against anything ferrous, including the block or sheetmetal of the inner fender. Same deal with engaging the motor, but the duration is fantastically short-duration. Battery cables aren't shielded. The windings of the pickup coil...pick it up. If the windings get an induced positive voltage, the module ignores it. If the windings get an induced negative voltage, the module triggers a spark. If that spark happens to travel to a rotor that points at a cylinder that has burnable mixture and the piston in the right (wrong?) position, you shatter the starter motor.

That covers the pickup coil windings. I have no idea at all about the ignition coil windings.

But what the hell do I know? I don't work in electronics. I didn't go to school for engineering. I used to fix cars. I'll update my hypothesis when someone gives me a better one, or when I get older and smarter.