Worst Automotive Parts / Components of All Time: GM HEI Ignition Module

[@brentfellers9632]

Hei was a huge upgrade from points

[@jimpalmer1969]

I've owned a couple of HEI equipped vehicles. A 1975 GMC w/ 454 and a 1981 Eldorado. I had the truck for 15 years and never had a problem with the module. The Eldo was blowing one about every month. A close examination of the factory wiring showed a ground that was missing on the car. There was a thin metal strap in the distributor cap that was missing. Once the ground was restored it never blew another module, but it did blow a couple of transmissions. That is another story.

[@warricksmith2640]

Exactly I eliminated blowing modules by running a separate ground from Distributor body to good engine ground. Been good for 5+ years now. Still carry a spare just in case but gladly haven’t needed it.

[@Tipman2OOO]

@@warricksmith2640 wow are you serious that's pretty hilarious, they could have actually prevented the problem had they build it better.

[@Tipman2OOO]

@@warricksmith2640 and I don't even mean the part itself, just the ground!!!

[@billc7187]

I've been thru the ground fix suggestion to no avail, they still last about 2 years in my 75 Corvette. I always carry a spare and have used it twice on the road.

[@billc7187]

I meant to add that I took one of these AC Delco failed modules apart once; the electronics are filled with a clear epoxy. Under a microscope I found an integrated circuit that had tiny jumpers welded to it and the other end of the leads welded to the circuitry. One of those wires was open in the middle. Looked just like a blown fuse would look. The ends of the tiny wire were round as if they were over headed. I suspect over voltage from some failed component overstressed the wire and it blew.

[@scottymoondogjakubin4766]

I love the gm HEI ignition system ! an upgrade with accel components never failed me ! what did fail on me was using a cheap rotor ! the carbon nub that makes contact with the center tab would burn thru and cause a misfire or no start ! and always carry a spare module ! the real beauty of gms HEI is it only needed power and rotation to operate ! chryslers had the dreaded ballist resistors i owned 2 and always kept spares in the glove box ! pretty cool channel you got ! very knowledgeable and informative !

[@richardprice5978]

i cannibalised my k1500 1986 for awhile and my 1970 b-bbm ran better with it. but yes on that engine all old school or new 2010-up engine management not the uncanny valley in-between the 2

[@Koexistence13]

!

[@sauluribe7082]

Anybody saying it's not a good system I disagree.

[@edwardmartinez9459]

Also rotor burn you check and there's no spark so you think HEI module. but don't forget that rotor look for a burn hole hard to find when it's black plastic. if you can't see try an old good wire on the center button the other end to everything connected crank it if you see spark it's the rotor for sure not the module.

[@scottymoondogjakubin4766]

@@edwardmartinez9459 the voltages are unreal ! i upgraded my 68 c10 to hei and got a mile down the road on a rainy day it started running bad ! i forgot to tighten the distributor hold down clamp ! truck was still running and i went to turn it and got knocked on my ass ! I'll never forget that ! never had a prob with hei since !

[@chrisjeffries2322]

I had a 1976 Nova 5.7 that had 250,000 miles before the valves pounded out, it had the factory HEI module still in the distributor. At tuneup always clean and replace the white module paste under the module, lube the centrifugal weights. Then check the vacuum advance canister, along with the Cap and 8mm plug wires. Then always install a new distributor HEI Rotor and Spark plugs.

[@VinnyMartello]

If you take care of your machine it will take care of you.

[@THE_DOC_RAD]

Hi Adam, just wanted to add some thoughts for clarity on the issues seen with GM's HEI modules. The original modules were white in color when they were incorporated in the familiar large-body HEI distributors in the fall of 1973 for select 1974 model year vehicles. By the fall of 1974, all passenger cars (the 1975 models) received HEI ignition systems to meet the increasing demands for Federal Emissions requirements and basically provide a "hands-off" approach to maintenance on the distributor which affects ignition timing (as anyone with points will know that regular maintenance is required) and ultimately the emissions out the tail pipes. Unfortunately, as you stated, things weren't so hands-off. The original white modules were VERY problematic. This stemmed from the fact the internal control chip designed by Motorola had an output transistor (the main switch for turning the coil on and off to generate spark) was not adequately designed to protect itself from back EMF (this is the spike that occurs when the magnetic field collapses when the power to the coil is turned off). To add to the problem, GM increased the spark plug gaps to coincide with the higher available voltages from the HEI system to ignite the leaner fuel mixtures being used by the industry at that time. The weakness in the module was exploited by these conditions. Many times not only did the module have to be replaced, but also the integrated ignition coil as a shorted module with constantly supply un-interrupted power to the coil, thus overheating and shorting out the internal windings. GM was then faced with a full on replacement campaign to change out the white HEI control modules with the more reliable black colored modules. Spark plug gaps were also closed to reduce the risk of misfire/back EMF events. The biggest issue is owners using supplied (or purchased on their own separately) silicone grease/dielectric grease/"tune-up" grease under the module. Completely WRONG. A good heat sink compound paste needs to be used. It is opaque white in appearance as the silicone stuff is clear or translucent. It is critical to provide the thermal conductivity between the bottom plate of the HEI module and the mounting pedestal in the base of the distributor with the use of the heat sink paste compound. You did hit the nail on the head with N.O.S. parts. Modern components (even genuine GM replacements) are all made off-shore and the quality is lacking. Even simple replacement points for points distributors are lacking! I've been in the electronics industry for decades and worked on cars and electronics for a long time. My classic car retains the original Delco distributor with points as I know as well as others, with electronics, it is not a matter of IF it will fail, it is WHEN it will fail.

[@donreinke5863]

Ah, then you should be familiar with the early Ford Duraspark ignition modules whose failure rate was so high that Ford was starting to get a bad reputation for the cars so equipped...1974 and newer. They would either stop functioning altogether or develop a "hot open" when the ignition would fail after some minutes of driving, only to work again when they cooled down. Ford improved the module circuitry on replacement modules, the upgraded ones were identified by sticker on the module which read "Motorcraft..Tested Tough" If we didnt see the sticker or a quality aftermarket module such as NAPA/Echlin or Standard Plus--we replaced it, and NOT with the Wells junk that was common in the day. These failed at least as often as the GM HEI modules, and the other problem with the GM distributor was replacement of the rotor with a cheap aftermarket unit which would often burn through in the center shorting the spark directly to the distributor shaft.

[@chrishensley6745]

You are dead on man.......down to the RIGHT grease that goes underneath which I have seen guys do soooo many times years back.I still run 3 G.M. s with this style module installed right with quality part is and excellant design.

[@pancudowny]

Your last two paragraphs sound like good reasons to swap-in an MSD distributor. [:\

[@codyluka8355]

@@pancudowny Unfortunately, MSD is not as good as it once was. They have issues now too. A lot of this stuff is now made in China and it's all crap.

[@jimmccoskey8253]

BTDT...You are exactly correct in every portion of the failure mode description. The original black GM modules are the only ones that are worth using as a replacement. Other aftermarket modules are junk, Pertronix included. The white thermal conductivity paste (don't use the clear grease, source the white from an electronics store) is also a key element in the reliability chain as heatsinking is absolutely necessary with these modules. It's also a good idea to tape a piece of 320 or 400 sandpaper to a piece of glass or other very flat surface and lap (rub) the metal base of the new module on the sandpaper to ensure flatness. I had one module with one of the two staked eyelets (rivets) that extended below the metal base mounting surface of the module, ensuring a terrible heat transfer surface. A SPARE IN THE GLOVE BOX, WITH TOOLS, is mandatory!

[@stoneylonesome4062]

This is a very good series idea. A lot of people talk about engines and transmissions, not so much about individual commonly shared components.

[@redband6011]

I've been using GM HEI ignition distributors on all the vintage and classic GM cars I've had over the years and have never had a failure. I use them today in both my 71 Nova SS and my 72 Buick GS (retro fit). I remember my brother had a Pontiac Grand Prix that had the module fail on the way home from picking the car up brand new from the dealer. That was the only case I was personally aware of. I was in the construction business for over 20 years and we had a large fleet of pickups, mixed Ford and Chevy's and I never recalled having an HEI failure. Actually, we were also in the snow removal business and everytime we had temps go below 0-5 degrees, a few of our Ford plow trucks wouldn't start (they were parked outdoors). We had to pull the ignition modules off the drivers side fender well and warm them up. Fixed. Maybe I was just lucky but I still rely on and have confidence in the HEI system. Mazda, Toyota and a few other foriegn makes had their modules in the distributors. My dad's Mazda MPV had a module failure in 1994 and the module was not replaceable. He had to buy an entire distributor at the tune of about $500. Ford Probes used the same ignition.

[@member57]

My experience is the same as yours. I have had north of 30 GM vehicles, never had a HEI fail. Didn't even know this was a thing. I upgraded numerous pre 74 to HEI. I also replaced DuraSpark modules with GM HEI.

[@richardprice5978]

getting good QC easy and ok cost, points or carbs based systems parts ect. in 2022 good luck i quit and moving forward with my classics ( 440bbm/hemi ) is modern engine control 2005-up as the aftermarket makes kits/diy for older generations of engines ect. but im not driving a pebble wining car ether so i see it doesn't matter as much if it's modified tastefully

[@bbb462cid]

The 1972 GS uses a slightly different shaped ram air bucket on the distributor side compared to the earlier models with that cool air setup. No fitment issues? I didn't use the radiator hose bracket off the t-stat housing on my '70 with the HEI, and I used an Edelbrock dual plane intake, the iron one was just so heavy. The aircleaner sat a little closer to the hood in my car but it worked just fine.

[@spikeprotien9023]

I remember the GM HEI the coil could put out 50k volts. When the plug wires would go bad and create an open circuit the spark would usually jump through the rotor and ground to the centrifugal weights, you could tell from the rust on them. Of course every now and then the current would hit the module. Game over. Thanks for covering this!

[@GTRxMan]

The problem with electronic ignitions, beyond the thermal/weather related issues, is that their life cycle curve is basically a cliff. Unlike points and condenser systems, they don't gradually degrade with perceptible differences in performance. They're simply on/off and as Mr. Murphy states, they fail at the worst possible time.

[@willallen7757]

Awesome analogy .

[@Tipman2OOO]

Wow, completely corrwct!

[@jeffbryan3224]

I've replaced at least a half dozen in the same vehicle over the years. The most recent was just last week and I got a SLIGHT warning. (not a great warning cuz I didn't realize what it was warning me of) Shut it down hot. Went to buy milk. Came back and it stuttered on startup like it was somewhat flooded. ( it NEVER does that). Drove it home and parked it no issues. Wouldn't go again. Installed spare I bought only 2 months previous. Didn't even trouble shoot it. Just prayed it wasn't a dud right out of the box like the LAST one I got at NAPA!

[@richardcumber5476]

The rest of the known automotive world installs an HEI and makes an oil pump primer out of the old points distributor.

[@countryroadautopartsusa6466]

I never forget my first and only experience with a failed module back in 1997. Going 70 MPH in my 1981 Trans Am in the "fast lane" of the local interstate and cruising, suddenly the engine shut down and all the warning lights came on. I was able to shift the automatic transmission to neutral and nurse the car to the shoulder. This is an interstate with 5 lanes, mind you and it happened around 4 PM semi-rush hour. Like others have mentioned, the problem is that its failure is sudden death, and you get no advance symptoms whatsoever.

[@catsaregovernmentspies]

I heard of people wiring a backup module to a toggle switch to avoid becoming stranded.

[@richardprice5978]

@@catsaregovernmentspies my k1500 seamed to always fail in the driveway sofar🙏🤞 after starting up and putting in gear aka stuck at the house 🏡 and easy fix vs no mans land. and yes keeping cold 50-65 f and using better tremale pastry lol from the computer 🖥geeks does help as does keeping the turning + battery/alt 👌ect.

[@shedred1967]

@Logan Forney race cars do it every time. And yes, my truck has one thermo pasted to bare metal on the firewall, wired on a switch. My tach fails, I switch and Ignition!!!!!!!!! I like to street race to the speed limit in my old jalopy and patina'd 79 chevy 3/4 all-time AWD that looks like a slow one. It's overbored, sbc 400, with AFR 227, drag race cylinder heads with offset lifters prove otherwise. People will pass me at full speed when I shut down at the speed limit. I've got them until I do. I had a Honda passport really upset in a 60 zone. I left him at the light, he floored it and caught up to me at 40 mph. I floor it to 60, completely dusting him for a few seconds when I shut down and he goes peeling by me with bald tires to be pulled over with his speed being over 80 mph I'm sure! Lol Baiter!!!!! People hate that old chevy being fast at all.

[@richardprice5978]

@@shedred1967 as a teen-26 id have tried street racing but my old man would have strung me up by the rafters lol 😂and then i got married and the wife didn't want to be a widow and or stupid in my 68 C10 or k1500 and more so in the 1967-70 charger ( as one point we "shared that car" and mom hates that car 😂😁 i told her at 14 i was going to buy one so good luck stopping me ( By 21 i had it ) besides most of my bs was in a v6 sedan or the rusty C10 SBC-sm465 4:10fg lol 😂as the bbm charger is a 🚓magnet lol ) or her caddy pissed 😤😡 off so i limted my self to "testing parts " 😉😁 and or not breaking and laws or getting chout

[@richardprice5978]

@@shedred1967 is yours a stick? because at 16 my k1500 700r4 went bad and a buddy at the time was parting out is k1500 1-ton sm465 so my mom threw a fit somehow in her mind that = a 6c chevy on full kill lol 😂no way and she would have hate yours as "its a race car" nope lol

[@bernardocisneros4402]

I've had 2 trucks with the GM HEI ignition module. A 1989 Chevy C1500 and a 1992 GMC Sierra both had the 350 (5.7L). I owned both of them since new and put over 260K miles on each one. I only had to replace the module once on each of them. Luckily, I was never stranded. My friend had a 1990 Chevy C1500 and replaced the module a few times before reaching 200K miles. It turns out he wasn't using "heat sink grease" between the module and the distributor because it didn't come with the module when he bought it. The ones I bought at Autozone didn't come with heat sink grease either but adding the heat sink grease was one of the steps in the replacement procedure in my Haynes' manual, so I bought some and put it on. I like to think the grease helped, but one thing for sure: I was lucky to get so many miles from these aftermarket modules.

[@JeffKing310]

I'm bloody addicted to this series! Thanks Adam, much appreciated.

[@johntierno546]

New to your channel by the way and enjoying. I did 17 years as a GM dealership mechanic and the biggest component failure that I remember was when they went to the plastic intake manifold gaskets on V6 engines that carried coolant through the intake. The 3.1 or 3100 they may have called it and the 4.3 come to mind. This was in the 90's and Dexcool had come out too. These were 100% failure rate for coolant leaks. Coolant would leak externally and internally at the corners of the intake. It wasn't if but when. You would pull off the intake and those plastic gaskets were in pieces. I think the idea itself was as bad as the component. Felpro came out with rubber coated aluminum gaskets that were much more durable. We were paid a flat rate per job and I did so many I was making triple time on the 3100s. You could leave the rear valve cover on then use a line wrench on the rocker arms to open the valve enough to slide out the push rods and change the gaskets

[@Marc816]

You had to remember to use the insulating paste that came with the HEI module. If that was used, the module was good for a long time.

[@TheLionAndTheLamb777]

It's actually not for insulation, it's to help the heat transfer from the HEI module into the metal of the distributor.

[@rickh8380]

@@TheLionAndTheLamb777 Exactly! Couldn't have said it better. Take care. Cheers

[@BrewBlaster]

The only problem with many of the replacement parts was the source was quite important; as the commentator mentioned.

[@fleetwin1]

I would suspect that many failures were due to improper paste installation as well. And, I'm sure build quality degraded over the years as this system was changed and quality was forgotten about.

[@johnl455]

I've been driving GM HEI since 1976 (including in my 77 GMC Motrohome which you have referenced)and never had a module failure. You have to keep all the secondary components in good shape-- cap rotor wires and plugs and gapped correctly (.038") Any degredation in the secondary allows the coli voltage rise to increase very high before discharging. This proportionally (it's a simple windings count ratio) raises the back EMF to the module when it opens the primary circuit. They can take this for a while but not forever. Also the heat sink compund dries and shrinks after 30 years and does not provide good heat transfer. Furthermore some incorrectly use dielectric grease instead of white heatsink compound, which works but not as well..

[@lesliemclean4381]

One thing i notice when i did use dielectric grease After a year i would go back to look under ignition module,and the grease was still there.That clear grease that came with the module would almost or be gone under the module. Now i use the white heatsink grease .When i look under the module after a year it is still plentifully there.eleminating any chance of the module frying.Now to eliminate heat from the coil in cap by getting one to put on the fire wall.

[@LakeNipissing]

Interesting to keep a spare HEI module in the glove box... kind of like 1960s-1980s Mopar owners keeping a ballast resistor in the glove box! Never really had too many problems with the HEI, but the GM "Optispark" ignition system used on the 1990s LT1 V8s was not known to be one of the most reliable, and certainly not easy to access / repair, being behind, under the water pump. As a 1996 Buick Roadmaster Estate owner with the LT1, I can attest to this.

[@glennk1931]

Exactly Lake.

[@classicwefi]

95 Impala SS owner here agrees putting the water pump over the top of the distributor so coolant can leak on the ignition ,bad idea.

[@fredsimmons6188]

I used to carry around a spare Ford TFI module with me.

[@DYLAN102001]

Try an optispark in a 92 corvette. One stroke thru a rain puddle and the car starts missing, or dies all together.

[@scottg391]

The GM HEI units were substantially more reliable than the Ford units of the same era. I went so far as to mount a second module on the fender well of my 79 Ford truck just in case the operating unit failed. This eliminated the need to rifle around in my tool box looking for a new one on the side of the road. I would simply plug it in to the new unit. 3 times in 3 years. I never had a factory GM module fail. As a rule I replace the module along with the cap and rotor at tune up time. Easy to change and not expensive to purchase. The aftermarket modules are junk, especially Petronics.

[@rubenp8750]

Yeah those Ford modules were crap but i bought the house brands from the auto parts stores. The oem fords were better built.

[@dougpersell8776]

You can refit a GM module to a ford.

[@MrWayneJohn1]

I couldn't disagree more with your assertion that the GM electronic modules are one of the worst components in the auto industry. Leaving a person stranded was far less likely to happen with an ignition module than the "good ol' points" system. Points systems are in CONSTANT failure mode as the rubbing blocks wear, condensers fail, points arc and corrode, etc. After-market replacements were and are often cheap imitations of the originals, so you can't bash an OEM part for that failure. I worked as a mechanic at a GM dealership and can't recall ever replacing a failed ignition module. I drove a late 70's Ford and at the very least, had to annually replace the failed 'brain box' mounted on the inner fender. Ford's electronic ignition was much more failure prone than GM's, and let's not even discuss the Mopar junk that was mounted to the air cleaner - that system was NEVER any good. Age is not an asset to electronics so if you're asserting that the original parts are currently failing on low mileage cars from that era, then that's not even a viable argument. Replacing a GM ignition module is a quick operation, one that takes much less time than replacing and setting points.

[@caseyrevoir]

A preventative measure is to refresh the compound between the module and the mount, and flat file the mounting faces. The white Goo never provided is "Super Lube #98003 Silicone Heat Sink Compound" (made in USA). The replacements come with dielectric silicone grease that although is not inhibitive to heat transfer, does not enhance heat transfer either. Such usage is to prevent water ingress and corrosion only. Do not use compound meant for computer CPU's because the stuff goes bad sitting for 3 years or while in use for 5 years (such as a great Noctua Brand paste). The Super lube stuff seems to last a looooong time (decades easy), and is what you find on everything (MOSFETS, etc...) Zinc oxide in the product makes the silicone transfer heat better. Unfortunately I have not found anything with a better heat transfer ability that has the extended service of the plain white Super Lube stuff. On my ford I modified the distributor mounted TFI or TFI-IV (Thick Film Integrated Ignition) module to a later designed fender mounted module. (EEC-IV) I'm working on a video documenting the mod. Ill try and remember add it to the comment when finished.

[@jayrider892]

As a 70's and 80's era GM tech, seems I remember replacing more failed pick up coils than modules. This issue went away when they eliminated the vacuum advance which would flex the wires on the pick up coil to the point of breaking. I still have a collection of GM pick up coil magnets on my tool box...

[@jimsix9929]

yes same here, you can only flex a wire so many times it is going to break

[@mikechasse1016]

I worked in GM garages from 79 -88. The early HEI modules had issues but from like 78 on they were quite dependable. The biggest culprit I found were aftermarket rotors not working. You needed to use a white GM rotor. Black or blue ones would fail right out of the box. You need to do a video on Chrysler ballast resistors. Talk about leaving people stranded!

[@ronschauer839]

I have never had a GM HEI module fail in any of the dozen or so GM vehicles we have owned that used them. However, I always placed generous amounts of electronic-grade heat sink grease between them and the distributor bodies as soon as I could after purchasing the vehicles because I was aware that they ran hot. On the flip side, I ended up donating a Ford truck that ate firewall-mounted ignition modules on a regular basis because I became so sick and tired of dealing with them. And I had an MSD 6A module on my last truck (K1500 Chevy) that stranded me on several occasions. I would be driving along happily and then sudden silence with no restart and absolutely no prior warning. It got so bad that I carried a spare MSD box (despite the cost $$$) before I gave up using them completely..!

[@jamesemmett864]

The distributor on my 1975 chevrolet truck finally failed last July. Don't know exactly what failed, but it was burning hot. I was amazed that an original component (excluding the rotor, wires, distributor cap) could last that long. An original GM replacement cost less than $100.00.

[@vincenzodigrande2070]

If you look on my channel, you can see I made an ignition system on my car using COP and it didn't improve reliability. I was surprised at first, basically there are many arguments going for it, and it still might, but long story short, what I learned from it are: 1. New isn't always better (the allowed dwell times were really low, lower than on the single coil on the old system that had to do all the cylinders!) 2. Coils on a heat cycling and vibrating place last shorter. 3. IGBT transistors on heat cycling and vibrating places last even shorter (best have the IGBT pack located somewhere further away from the engine) 4. IGBT driver circuitry inside the COP's is even worse, best halfway solution might be to put just coils in the COP's and let the drive circuitry and IGBT 'amplifier' sit somewhere less shaky and less hot.

[@133dave133]

Car parts, or the lack of. Finding good quality replacement parts, or NOS parts is getting hard. I'm not a Chevy at all, but I couldn't resist. I bought a very clean, sheded it's whole life, one owner, 1982 G20 conversion van with a 6.2 diesel. Chevy made millions of G20 vans. I can't find good or bad quality parts for it, including NOS parts. Chevy made millions of 6.2 diesels, same issue. It's getting kind of scary. Even getting a gasketed windshield is getting hard to find. I'd like to really start driving this vehicle, but I'm worried about being able to maintain it as well. Doorman has become the Harbor Freight of car parts. Although Doorman has stepped up to the plate in many cases, their quality is terrible. On the ignition side of things, I always carry a spare ignition module in my 1984' Bronco. Cell phones have made being stranded easier these days. Back in the day, you'd better have a good pair good walking shoes.

[@guillermojimenezcastelblan8456]

Hello Adam, nice explanation. In my former spare parts selling job back in the 80's and mid 90`s, the electronic ingnitions systems were a tricky stuff for all old school mechanics who believed that contact points were the real deal. No way, the electronic ignition was something positive devices for the automotive industry, thanks to Mopar, the very first one to featured such an element. The heat inside the distributor probably caused over heating component isolating the power supply, so fot my personal experience, the Mopar system was superior over the GM H.E.I one as I could see over the years, because the Ignition External Module from Mopar did not suffer for heat or humidity, because was an external fitting unit, almost placed above the inner fender dust skirt or over the fire wall. In my Chevy Celebrity I owned some years ago, and with almost over 162.000 miles. that module was the original Delco Remy factory unit!!, believe me, but was little different, with 4 or 5 contact tips rather than your 4 contact module, 1875990 GM catalog part number. They were cheaper to buy, in many brands, such as Wells, Standard, Valley Forge, General, United among many others as well, keeping a higher price for the Delco Remy unit. But to be fair and serious, the HEI ignition GM system is a world class design, very dependable, long lasting performance. Thanks for the info, very ilustrative. Salute, from Bogota, Colombia. Take care, man.

[@danielslocum7169]

the old mopar system was very good also.nowdays though,its hard to find a good replacement ignition module as they are all chinese junk.

[@TheOzthewiz]

Mopars of the '60s and '70s used a 'power' resistor in series with primary coil circuit to drop the input voltage to 6V after startin g the engine. What happens is: that HOT resistor gets hit with rain water, causing the part to crack resulting in engine shutdown! The engine will start normally, but will shut off as soon as you release the ignition switch!

[@joelongjr.5114]

My dad's last pickup was an 86 Chevy half ton, 4.3 L Vortec V6. His Chevy ate those HEI modules like candy. The V8 version was about 20 bucks at NAPA, the V6 was $100. I was working for a division of Echlin at the time and he asked if I could get some modules with an employee discount. I found out I could buy them for about 5 bucks each, so I got 3 for him. He replaced only one and that lasted for the rest of his life. When mom sold his pickup after he passed away in 1993, the other two HEI modules were in the glove box.

[@mikechasse1016]

I also worked at a Napa store for 10 years. Think I sold 1 HEI module. Sold dozens of Ford Modules Part # TP32. Also had a Chevy wagon in the shop once that had most of the distributor cap missing and it still ran!

[@tbm3fan913]

So I have five cars between 1965-1973. The 73 being a Dodge and the others all Ford products. All the Fords use the Pertronix II since it first came out powered through a relay. One car had a first year Pertronix I and all have performed great. However, for some reason the Dodge had trouble with the Mopar system and also blew two Pertronix II modules. I made my own HEI system for the Dodge using an NOS GM Module, a Ford e-coil, and powered through a relay. The module attaches under the Mopar distributor using the heat transfer paste. I get 13 volts to the ignition, great looking plugs, quick start, and so far am now 6 years into.

[@life_of_riley88]

Yeah I have an HEI on my 340, runs great. Hot spark, and has zero problems with a 10.9:1 compression ratio, or 7000 rpm. I think these systems get a very bad name from GM rushing them into production too early.

[@pjmazar4533]

Thanks for the informational video. I couldn't start my car yesterday, but it fires up and is running today. Is there a test for the module or do I just replace and be done with it?

[@robertlewis1965]

A buddy of mine was giving me and a complete motor a ride to have it installed in my car. 20 miles from destination the HEI ignition module died , fortunately we had a spare in the back of his truck . Now I always carry a spare in the glovebox.

[@onlyhereonce7290]

A very good series. Always fun to watch.

[@52CA]

This is why aircraft still use points type magnetos. Reliability is more important than emissions or power.

[@garypeatling7927]

This man explains it so well I try and tell people about new electronic modules

[@leroygreen1877]

Owned several GM's with HEI and only had one module go bad on me. The flaw is when the silicone dries up and the chip frys. Not a bad design when serviced right during a replacement.

[@njwebste]

I had four Hei modules fail in a month. All standard motor products modules, bought at the local parts shack. I got a Davis module off summit, no problems since.

[@67daltonknox]

All experience is personal. I doubt you have owned a vehicle with Lucas points based ignition, but these were awful whereas in the last 40 years I have owned 13 cars, bikes and trucks with electronic ignition without ignition problems. My last experience with points was on a group climbing trip to Mexico where a VW camper would not start. The owner was perplexed because he had just laid out a lot of cash on an extensive service. I fished out a plug and found no spark. Opening the distributor and removing the rotor, the points were shut because of a loose locking screw. Using a thumb nail in lieu of a feeler gauge, I reset them and it fired up.

[@markg6328]

Remember these issues all so well! At our shop we also would see the Ford TFI modules and the 86-92 various GM vehicles with what insiders called "Phantom Stall". On those GM cars we would have to look at the date codes on numerous sensors (crank, cam, MAP/MAF) and replace the ones in question. The worst issue was the intermittent "stall and cranks but won't restart". By the time the car was towed to our shop the car would start right up and could be driven off the tow truck and we were "unable to duplicate the condition". Customers were pissed to say the least. My brother and I wound up doing a series in Motor Age Magazine on how we finally repaired these intermittent problematic cars. Needless to say it took a lot of hours of driving these cars with scan tools and lab scopes connected to various components trying to duplicate the stall condition and catch which electronic sensor was out of range.

[@karlporath8904]

Little known fact. Later air-cooled Porsche and triumph (Lucas electronic ignition) used this module but in a firewall mounted box. If you need the Lucas part, it'll cost you $150 the Porsche part $400+ or you can remove the rear cover and just replace the module in the case for $30.

[@jeffshadow2407]

My 1972 Toronado has had the HEI system from a donor 1976 Toronado for over twenty years now. No failure, ever. My 1979 Pontiac Trans Am; yes, the HEI failed and Roger's Automotive in Orange, California repaired it in thirty minutes, including the tow!

[@timalentiev6276]

Good Video. Had a 81 Chevy Citation Duke engine that modules fail in hot AND cold weather…32 degrees. Also distributer gear that year changed to plastic/nylon. Only car that stranded me 3 times, and I tried to maintain it like an airplane.

[@cousinfester4621]

With the market flooded with only Made in China ignition points now, you might find yourself stranded more than you'd expect.

[@tacoheadmakenzie9311]

That's why I've bought several sets of 40 to 50 year old N.O.S. point sets in the swap meet section of car shows over the years. Old Standard Blue Streak or Echlin points are good.

[@rawouch]

Just had to replace ignition modual in a 3 week old Accel HEI. Car died while driving 3 days ago and just fixed it now Was driving me nuts because no one has a video on how to trouble shoot modual. Tested everthing else and all good. Watched 2 vids on bad modual so I said screw it spent another $50 bucks on Petronix Flame unit and started right up. Thanks.

[@michaelv3340]

Ford put their ignition module on the distributor in the eighties. There was a class action lawsuit and they had to warrant them to 100 thousand miles. There are companies that sell kits where you can relocate the module to the fender apron.

[@21stcenturyfossil7]

I seem to remember that Ford relocated that module to a bracket behind the grille.

[@pjimmbojimmbo1990]

I had several GM cars with HEI, and never had a Problem with any Ignition Module

[@Bbbbad724]

These porch chats are great! I hope that you have time to continue with them!

[@tonyscarcare5657]

Let's do one together on the early GM cable driven window regulators that was my bread and butter throughout the first decade of the 2000s. Grand Am, Alero, Intrigue, LeSabra, and so on.

[@scrappy7571]

Or go back further to the plastic tape window regulators. We had tape in bulk rolls and were required to replace the only tape. Ridiculous!! Funny how, now we almost never do electric regulator repairs on the newer stuff. my paycheck is hurting.

[@tonyscarcare5657]

@@scrappy7571 yep all those were guaranteed income and now they finally figured out how to make them good.

[@trainships1795]

I have only once had a bad experience with Mopar Electronic Ignition System in 1972 to 1989 Rear Wheel Drive cars. It was a 1976 Dodge Aspen SE Station Wagon. Water got in and fried it. Good thing it was still under warranty at the time. The K-Car Ignition System fail point is the Electro- Magnetic Pick-up, the little wires break over time. Should change it about the same time as the Timing Belt on the 2.2 and 2.5 liter engine.

[@fourdoorglory]

Nomination: Chrysler’s ballast resistor.

[@christopherconard2831]

A legendary part. Unfortunately for all the wrong reasons.

[@highwayman1218]

As a tech for alot of years from late 80s to early 00s. I really didn't have too big an issue with the GM modules. Honestly I dealt with way more GMs towed in with bad fuel pumps vs modules. Now the Ford Dura Spark was always an issue. At least they made em easy to replace. 😊

[@edwardmartinez9459]

They're ez to change but the connector could cause a no start and be hard to find.

[@davebaker9128]

I have moved this component to the firewall, mounted on an extruded aluminum finned heat sink from a p.c. of course with the white paste goo on the module, make sure all 4 spade connectors are snug and I would paint the connections with dielectric grease, never had a failure mounted this way, and I will never use Accel components because a tech at Accel let it slip when I called their tech support when I worked at a H-D dealership, that Accel had an acceptable failure rate of 70% right out of the box, they would replace the bad new units free of charge, but installing 6 or 7 of the same new part that was non-op right out of the box seriously cut into my paid work time as I would be paid book time to do a job once, if the new part was bad, I'd have to R&R it until I got a "good" one. And yes, seriously I have had on more than one or two occasions had to install every single Accel voltage regulator in the shop, only to tell the customer they weren't getting a chrome "dress-up" part but the stock, factory installed black regulator was the part that worked, didn't fail instantly, and if they absolutely had to, just block sand the edges of the fins lightly, and now it's shiny and custom, but I will never ever use any Accel products for any reason because of the incredible lack of quality control this company deems acceptable, by the way, I was a Jaguar dealer tech for years after I restored Jags from the late 40s through early 70s models, I also am primarily an engine builder, and after the Jag dealership I was the lead tech at a Harley-Davidson dealer for thirteen or fourteen years, I drive the same motorcycle I've had for 41 years, and have a Citroen 2cv that I've had even longer than the bike, thanks for letting me express my thoughts based on a lifetime of experience, db

[@chrispompano]

My idea exactly... Mount the module remotely to a computer heatsink with Artic Silver heat sink compound.....also use emf shielded wire.....and even extend it to mount under the dash. I went thru 4 Accelerent modules, they kept sending me free ones....I gave up & went back to a genuine GM MODULE!!!!!!!!!!

[@chrispompano]

I also read once to be sure to run a separate ground wire from the grounded bolt of the module to the distributor housing, the to the block to be sure the module has a good ground for protection of the circuitry......

[@freetoroam7769]

Another homerun video! When I bought my very low mileage '76 Coupe DeVille back in 2002, I read about some of the horror stories of this module. Even though the car ran great, I went ahead and changed out the module with a new one as insurance. I think it was an aftermarket brand though. Regardless, the car is still running great today. I really enjoy your videos and always look forward to the next one!

[@Primus54]

Hello Adam. Your channel has quickly become “must see TV” for me. Thanks! 👍👍👍

[@MrHewilson2]

I replaced replaced the ignition module on my 1985 Chevy LT-9 engine and it was original. The original mind you from 1985 still functioning in 2023. The problem was a burned rotor probably secondary to old spark plug wires. I went ahead and replaced the ignition module as well and bought a backup to keep in my glove box.

[@DrRust]

Compared to the ford and Chrysler ignition systems of the time h.e.i was the best, simplest and they all took the same parts. All the olds, Pontiac, Cadillac and Chevys shared a v8 cap and rotor or v6 and most of the 4 cylinders that made the parts cheaper and easier to get. I was told a story about my grandpa where he paid for a vacation to Florida from the mid west by fixing ford ignition boxes on the road side he just kept the 7 or 8 different part numbers in the trunk this was the late 70s early 80s I work in the auto parts industry and I still have more problems with none gm ignition systems and recommend to people that they should get a conversion h.e.i distributor for ford and amc motors that use that box on the fender

[@KO-pk7df]

Maybe because I was in Arizona and drove lots of miles I removed the Points/Condenser and installed the Pertronix electronic kit. I kept the Points/Condenser in the glove box but never had the any trouble. I finally installed a HEI from a used farm truck never had any trouble with it either. I believe everything you say because I know others had trouble so I maybe I was lucky for once.

[@bobqzzi]

One of those cost me a race at Mosport back in 1990. Was leading when it stopped dead.

[@mercedesclassicswithpierre1753]

i have never had any issues with points either. had a bad condenser once. even the dual points in my 1967 300sel are super reliable.

[@drf-1382]

The GM HEI module is not problematic. I worked as a tech in the 80s and 90s. Most GM ignition problems are due the pick up coil, oil wicking up the distributor shaft or a missing ground for the coil. The factory module pictured rarely gives trouble in my experience. Ford's Duraspark is really horrible though.

[@edwardmartinez9459]

The HEI rotor burns a hole in the plastic then spark goes grounds to the advance wight's no spark. Replace the old one with the DR#318 rotor from standard ignition it's almost burn proof.

[@billyjoejimbob56]

Adam: Always appreciate your point of view and understand that you are not a big fan of the early attempts at electronic ignition and fuel systems. GM's HEI, variable venturi carburetors, electronic Rochester carbs, and arguably the worst of all... Chrysler's Lean-burn! They were all plagued with teething problems, and the parts available now are ancient IF you can find them. However... you have what 30 or 40 cars? None are driven more than a few miles per year. Rebuild a carb and distributor and the car will stay in tune for a decade if you treat it to a trickle charger and some Sta-bil. Personally, I like modern systems MUCH better. Nine years, zero fuel or ignition system maintenance, original plugs, one new battery. Starts every time and runs like new!

[@VinnyMartello]

I still like the older stuff. I can replace the engine in my 66 Chevy four times in the same span it takes to replace the head gasket on a PT Cruiser.

[@zeon5323]

And the rotors would burn through and ground out the spark, and the wires that were in the distributor and went through the housing would break due to the action of the vacuum advance.

[@chrisjeffries2322]

Yes, burn thru rotors and burnet 8 mm plug wires.

[@21stcenturyfossil7]

And some electrical power would be capacitively coupled to the advance weights under the rotor and would arc at the pivots. The arcing caused pitting and freed up powered iron would quickly oxidize and form an abrasive right there in the pivot. Given time, the pivots would be undercut and the holes would be worn to slots.

[@donreinke5863]

We used to see both all the time.

[@paulstewartcrane]

My Dad had a 1977 Maverick 6 cyl. Great looking Blue, but a dog to drive. After having a 302 cubic 1968 Fairlane. The Module on the Ford Maverick went out 3 TIMES. And he worked for that company. He was very Unhappy. If it wasn't for the 1st Gen Taurus he bought, he never would have bought another Ford .

[@thomaswarner3060]

I sold/installed lots of ignition modules in the 80's and beyond. Yes the GM modules were quite common but FORD ignition modules were the "big seller" Stories back in the day...like Ford went ahead with manufacturing ignition modules after having over a 54% failure rate in prototype testing... Needless to say, there where broken down, mostly Ford's getting towed in to the shop from all over...

[@chrisjeffries2322]

They also were color-keyed at the box

[@donreinke5863]

If it wasnt the newer improved circuitry Ford module (Identified by a sticker that read "Motorcraft..Tested Tough" or a QUALITY replacement module (not the cheap Wells crap) we replaced the module to head off inevitable failure.

[@mikekokomomike]

They used to make these modules right here in Kokomo at Delco Electronics. Now the plant is empty and GM is using the parking lot to store unfinished new GM pickups, ironically waiting on chips.

[@sunbeam8866]

I remember back in the '90s paying a Chevy dealer for a new HEI module, thinking it would be better quality than aftermarket. Maybe it was. Imagine my 'surprise' when I opened the Delco box to find 'Hong Kong' on the bottom of the new module! Even worse were those GM HEI distributors with vacuum-advance. A wire to the captive pickup-coil would break. Then you would need to pull the distributor, drive the pin from the gear, drive off the gear, drive the shaft from the housing, etc.... Worst of the worst was the HEI on a Chevette with AC. It used the same massive HEI ignition-coil-in-cap unit as a V8, but with only 4 plug-wires. You couldn't do anything without first pulling the AC compressor AND its' bracket. Then, if you needed to remove the distributor, the fuel-pump ran off a cam on the distributor-shaft, so the pump had to come out too!

[@nathanrice1796]

You're the first person I ever ran across that said the GM HEI modules aren't very reliable, but I guess it's good to listen to all viewpoints. I would buy a replacement module from Pertronix or Performance Distributors.

[@RareClassicCars]

They’re reliable until they give out.

[@fixinggrace]

I prefer the old style breaker points too. Perhaps the worst electronic ignition module that I’ve ever seen was the Ford TFI module. I had a friend with a Ford tempo and escort with those on them and they failed like clockwork every year or so

[@jimc9581]

I haven't thought about this in a long time, always carried a spare under the seat just in case.

[@richardcrouse9074]

Putting some good quality thermal grease between the module and its base helps tremendously.

[@robertbennett212]

my 2003 Buick lesabre ICM failed in Chihuahua, Mexico. Due to the scarce availability of parts, my mechanic here in Mexico found a used ICM at the junk yard. I will replace it when arrive in Tucson, with a new OEM. Wish me luck!

[@jamesgurney6576]

A nice talk about electrical components on a cars , GM. I had an 87 Dodge D150 pickup with an 318 V8. I always keep Ed a spare ballast resister and voltage regulator in the glove box. I had to replace the regulator twice and the ballast resister once.

[@ceciltrane5418]

The other gizmo I remember lol

[@WinnfieldCustoms]

the only time my truck ever left me stranded on the highway it had no spark or injector pulse, got a ride to autozone and bought two ignition modules. never again

[@scolley0616]

My mother's 1978 Chev Monza with the Iron Duke 4. Went through several of these, left her stranded a few times. Knew to let it cool and then would work. Warranty replaced about 3-4 of these. This was the 1/2 moon 4 connector type, I replaced most of them myself. Used the gel as directed. Finally after these 3-4 replacements got one that worked for more than a few weeks.

[@Payne427]

My first ever vehicle was a 1994 lowered C1500 (Still have it) and the Accel Ignition module behind the cap decided to have a stroke while I was driving and it instantly shut off. Back then, I wasn't as knowledgeable as I am now about C/K series trucks so, I literally had a panic attack on the side of the road. Lol, my father is an expert mechanic and helped me fix it.

[@chuckmiller5763]

We always carried extra modules in our trucks in the early 80's. They seem to go bad when you hit the gas at the green light. Or pulling into traffic.

[@TheBrokenLife]

I've heard these problems reported from mostly the old timers that were there when they came on the scene in the '70s, but by the time I was driving in the '90s I never heard anything about it. I've probably put a half million miles on GM HEIs without ever having a failure. Maybe I'm just lucky?

[@life_of_riley88]

Nah, the modern modules last a lot longer and are more reliable than the parts of the 70's and 80's. It's a pretty good ignition system in modern times.

[@StephenGiovi]

Thanks for the info. I am working on a GM HEI, and at this point, I have had a great deal of trouble with timing the car. The timing mark is basically, all over the place with a variation of about 10 degrees. How should I fix it, I wonder? I'll work on that and possibly send some information which I've learned to you. Wish me luck!

[@robertbryce7626]

I have converted two Corvettes, a 350 ci and 454 ci over to HEI ignition during engine replacements, one in a 1965 Corvette and one in a 1968 Corvette. Both have been working fine for over 35 years. Had to replace several caps and rotors, but I have never yet had to replace a coil or ignition module. Don't know why you are having all these problems, but I have not.

[@The_R-n-I_Guy]

My mom's 88 Chevy Celebrity died on me without warning. I was young and knew nothing about cars. Luckily my friend's dad knew what it was and showed me how to change it. After that I started learning as much as possible about cars. Now I fix everything myself. So thanks GM. If not for being stranded by a bad component placement, I might not have been interested enough to learn about cars. Now I work at a collision repair/body shop.

[@robertthomas5906]

I had one problem with that module. It was in a late 1970s Chevy 305. I replaced it and it ran to being disposed of because the rings were shot. The HEI ignition was wonderful. I never understood why the spec was 35 thou for the plugs. I increased it to 55 thou and that increased the power dramatically. An old mechanic suggested 55 thou. All of my other cars and friends cars I did that to and everyone was happy about it. That car went from 15 MPG to 18 consistently. Points - love them while you have them. Friends that I know that still use points tell me that the quality of them are going to crap. One guy does racing in a Porsche. He had to break down and switch to electronic because he couldn't buy points that would work anymore. They're dying out. The only place that I know still uses them are prop aircraft. They have self contained magnetos. Two of them. Some old tractors have Bendix mags as well.

[@WhittyPics]

I had an 84 Pontiac Grand Prix that never had any ignition issues and I owned that car about 15 years. I think it was the early years of these systems from 1975-1980 that had the most trouble.

[@carlmatheny4517]

Yeah I had a 1978 TransAm and I put over 150k miles on it. Only thing the "pick up coil" failed at about 30k. Otherwise no problem at all.

[@georgemaragos2378]

Hi, great story. I am based in Australia and our local GM's are called GMH. We had point is GMH until 1982 ( strange as local chryslers got them 1973 and ford 1978/1979 ) We used the same bosch 4 pin model you should, however as ours was basically same 6cly from 1964 and same V8's from 1967 we also used the same distributor and what the factory done was added a metal "shield / plate" on the lower distributor body and mount the hei module on that metal plate A short 4 pin wiring harness went into the lower distributor metal body - while the distributor was basically the same and electronic internals instead of points they did get a larger diameter cap and rotor to stop the arcing between each lead terminal in the underside of the distributor cap Now these ran great for 5 to 10 years then the problems emerged, originally with V8's as the lower distributor housing is shorter and mounted basically rear engine like a gen 1 chev 350 / mopar small block Plus the module was in the rear so it was a pain, to note the rotor position, remove the distributor and work on the plate, new module would work 6 to 12 months then the same problem - the importance of the thermal paste was basically unknown and many people did not clean the surface and re apply the thermal paste 6 cylinders were actually OK as they were on less vibration engine, not driven as hard and the module faced east west with plenty of clear fresh air and not much water - there problem was being parked outside and the metal plate would tarnish and thus bad conductivity between module and plate A trick everyone had was throw a bottle of water over the module if it starts it was hot and you can run the car for another 30 mins / few days - if it did not start it and it was a hot day it was probably fuel vapour lock - another problem as we did not have fuel pump return lines on mechanical fuel pumps I had a issue with my car, the sparky was busy and he said " can you fix it yourself" i say NO, he said can you use hand tools, i said YES - so he spent 1 minute telling me what to do, i removed the dizzy, took of the module, took of the wiring harness, used a hand file and sandpaper on the mounting plate, applied the paste and bolted on a new module - reinstall the dizzy and he got me to look where the dizzy was now and rewired the firing order from there - turn the key - bang it fires up He just charged me the counter price for the module - and said if i have a problem come back, if the car runs hot ( as it was a V8 and the commodore has a cramped engine bay ) i can come back and he will do a mod, i told him i would see him next week and the car had messy under dash wiring due to a prior owner being a butcher and a radio install, he said if i promise to come back he would order the nder dash harness from GMH and help me out I week later i turned up he had the harness and i was simple to removed from the fuse box power and use the new speaker wiring, he asked about the HEI and i said fine, and he said we will do the mod - it was simple, it was a simple rectangle hollow box section of aluminum - he had a few 6 foot lengths of it, he chopped of about 4 inches of it, ran a large screw into the firewall and mounted the alloy then grabed a premade 4 pin extension harness he had and with new thermal paste moved the bole from the dizzy to the firewall, the hollow box section had better thermal conductivity plus being hollow and on the firewall was no more vibration of the engine. That worked for the 8 to 10 years i kept the car, he also had some mopars and used that module instead of the factory ECU The secret was simple use genuine bosch component, keep them as cool and vibration free as possible

[@TeeroyHammermill]

It typically last around 20 years before corrosion takes it out. The failed modules usually have green electrical corrosion inside on the contacts where they connect to the circuit board. It's actually a well made well insulated part as the module circuit board is covered in heavy silicone epoxy so it resist moisture and corrosion for possibly decades. Usually when they give out, the car will restart in a few hours then conk back out again when the module overheats. I've only had one fail on me but the car was 22 years old at the time and had 145,000mi on it. Possible symptom of it going bad are low struggling acceleration in hot or damp weather.

[@mysock351C]

"OMG please make it stop. PLEASE! WHY, OH WHY? I JUST WANT TO DRIVE HOME!" Typical response to having a distributor with one of these. The major reason they died so fast and so often was the boneheaded decision to use the distributor base as a heatsink. Its sitting inside a hot crankcase. It has a worm gear on the end of it that makes even more heat. Its already at about 230°F with nothing else attached to it. Why not put a semiconductor on it that has to pass up to 15-20A? It will stay cool, right. Well, not really. They always died a slow death because of that, with the spark getting weaker and weaker until it just quit altogether. I can't say what a relief it was going to the L31 crab distributor system. People would say that's waaay worse, but add a billet distributor, flip the distributor gear around backwards, and change two parameters in the PCM and it literally runs forever. No more spare modules in the glovebox. No more misfires. No more lack of power. It just works like it should. The module is externally heatsinked and has an IGBT die in it the size of a postage stamp and runs stone cold. With the modified distributor the only reason I had to finally change the cap was the distributor simply rotted out inside and needed replacing. Greatest ignition system GM never made. Shame as one simple change makes it bullet proof.

[@scotttwombly6528]

80’s 90’s Jaguars Used this ignition module. From Jag over two hundred bucks to replace. You could open up the Jag module Enclosure. Then put a 18 dolled GM modular in it.

[@RGIGANTI]

This takes me back to my first car, 1976 Chevrolet Malibu Classic, that module went out at 60000 miles at a gas station.

[@Cameraman148]

I worked for Autozone for almost twenty Years, this part was a Hugh seller and I have tested hundreds of these, the aftermarket does have some problems for quaulity....

[@johnsalster8206]

My '88 XJS V12 HE has a GM HEI module located inside the AMP which is mounted on the driver's side intake manifold. That HEI module is, by far, the biggest problem I have w/the car. I always keep an extra AMP and an extra HEI module (along w/tools) in my trunk. I have had modules last for as long as 2 years, while the last two I had both lasted less than 2 hrs. Prices have doubled in the last couple years (although still around $50), but it's really the issue of just shutting down somewhere out on the road that sucks....sure wish I could find an alternative.

[@JAMESWUERTELE]

Ford 7.3 power stroke Crank Position Sensor. Most of us owners keep a spare in the glove box and a ratchet,. The gray one now to my knowledge is the last revision. Oh and the fuel bowl heater. I think it’s fuse #12, also causes a no start condition. Pretty common.

[@martyjoseph9507]

My 76 Nova went out in the mid 80's but I was lucky enough that it only failed when it was cold, once I took it off and warmed it up with a hair dryer and reinstall it the thing would work fine until the car again sat for 8 hours or so. It took me a few days to secure a new one so I got pretty good at pulling things apart.

[@MrGilstorf]

Good advice Adam on the HEI. My Chevelle had an old MSD electronic ignition and I debated putting an HEI in it instead since the MSD was failing intermittently, yes leaving me stranded a few times! It was tough to troubleshoot since MSD kept saying their ignitions don’t fail intermittently. Not true! Long story, I ended up getting a new MSD, so far after one year no issues.

[@drsnooz8112]

I hate to admit you're right about points, but my 89 Accord has been dead in my yard for the last few years because I can't find a working ICM or pickup coil for it.

[@johnkrag6]

The Olds V8's I'd say '75-'77 had .080" spark plug gaps to fire lean idle mixture. This lead to the "rotor" burning a hole to centrifugal advance. Also the plug wire terminal closest to a coil mounting screw would burn through the plastic causing a dead miss on that cylinder. Another issue was rust would lock up the centrifugal advance. That lead to removing distributor taking it all apart glass beading the advance and greasing the reluctor on the shaft. Also the nylon bushings on the weights would fall apart. Thexton at that era had a kit to install new improved bushings on the weights. There's no telling how many HEI's I rebuilt in that time. Oh I might add on the Olds. We'd knock the plugs out of the carb to richen idle mixture and install .035" gap spark plugs.Happy customer. In addition while the distributor was apart a new GM pick-coil was installed. The white and green leads would break caused by action of vacuum advance.

[@Ian-of9oi]

This is the first time I ever heard a guy complain about these. Only time I ever saw one fail was an aftermarket module.

[@gkindustrialmachine1]

64 deg f in Phoenix Arizona... High today is expected at 73 deg F....

[@royshashibrock3990]

Just wanted to remind anyone doing this upgrade about a safety feature of these "big cap" HEI distributors. If you attempt to start the engine with no fuel in the carburetor bowl (no fuel getting to the cylinders), the module will sometimes shut down and the engine will not fire or run. From that point, as long as the key is not turned fully off, the safety will remain turned on, and the distributor will not function. To reset it, turn the ignition key fully OFF (no power to the distributor), wait 8-10 seconds, and then try again, this time, making sure fuel is getting to the cylinders. Even foreign made versions of this distributor have this feature. This happens because inductors (coils) pull more current when the resistance it sees increases. If there is no fuel in the air around the plug, the resistance seen by the coil increases greatly, which in turn means the coil in the distributor will try to "sink" a much higher current. To prevent overheating and destruction of the ignition coil, as well as damage to the electronics, a type of auto-reset circuit breaker was implemented in the module. Once activated, it will remain "on" as long as there is power to the module, and can be reset as described above. My guess is that it was too expensive to implement current limiting in the module and this was the solution used. I can't tell you how many guys I know who thought the distributor went bad and got rid of them because they did not know the above.

[@americarsqueensland1667]

Points Distributors are ultimately more reliable If you do the occasional maintenance BUT I have to say the GM HEI distributors fitted to the late 1970's onwards are very durable and reliable. I have several oldsmobile V8 cars with HEI distributors from 1978 to 1987.

[@Wiencourager]

The competing Ford Duraspark system had issues too, they used a single low gain transistor, which required high current in the driver circuits with big hot ceramic resistors, which generated heat and the thermal cycles would degrade the circuit board connections. some of the better aftermarket modules (Wells) had a Darlington transistor for more gain and had driver circuits that didn’t produce so much heat.