My first mopar "stranded" moment with the HEI setup

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gdizzle

gdizzle

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Well it happened yesterday, driving home in my 66 dart 270 sedan full of groceries. Stopped at a light, then the car just stopped dead. Tried to start it and just spun with no spark ( I guessed). I have had the car for almost 2 years and had recently (2 months ago) completed the HEI swap from the old points. I thought I was feeling over confident that the car was stable and good to go for years to come.
(I am new to all of this mopar stuff, learning from you guys on the site and reading materials)

So I got out and pushed to get the car to the side of the road. Waived people to go around me (no e flashers on this car). Popped trunk, got out my bag of tools. Popped hood, everything looked ok. Why in the hell wont the car start? Gotta be ignition issue? So the only thing I could try was the ignition module. And yes, thanks to you guys on this site, I had a spare module in the glove box. Because of how I installed the GM bracketry it is a serious pain to get that module off, but I did. now grey paste all over my fingers. Put the new module on, reconnected battery. started right up. Whole thing took me about 15 minutes.

Now if you have read this far my question is: Why would the module fail? It was a Standar Motor Prod LX301 for $35 on Amazon. (which I have now asked for refund).
I had noticed the last few mornings when I started the car it was sorta rough for a few seconds, but then evened out. Was that a sign that the module was farting out?
Time to order another spare. When it started up, the first thing going through my head was, I do not have the stomach for the HEI, and the points are going back in. But I have since thought I would give it another try and see if it happens again. Fool me once, shame on you. Fool me twice HEI and shame on me.:)
 
I have had mixed results with replacements. Some last awhile, some don't. Have seen them crap out in different ways. Quit once they get warm and act stupid cold or just spit and sputter till they fail. Just one of those parts that you're better off buying local.
 
Always at an inconvenient moment too..... :(
Points are very reliable if you don't mind looking in there once a year or every 10,000 miles. Not the most efficient, but simple, cheap and very serviceable.
I've not had any issues with the Chrysler electronic ignitions. More efficient than points, and a lot less maintenance.
 
It happens, but it's rare.
It's possible that the module was sold as a Standard Motor Products part, but actually isn't also.

Been running the same module on my car for 4 years and thousands and thousands of miles without so much as a hiccup, but I use factory GM 8 pin modules.
One other thing is that 4 pin modules are prone to low voltage death, so you may very well have run across one of these shortfalls.
The 8 pin module is a lot more stable and less prone to voltage issue's, and this is one of the reasons we use them in our HEI Kits instead of the four pin.
(well that and the 8's are a much more reliable and visually cleaner connection setup.) which could have killed your 4 pin from low voltage with the blade connections.
 
They failed a lot on GM's back in the day. If an HEI GM wouldn't start it was the module 90% of the time. The new modules came with a small packet of dielectric grease. I don't know what the grey goop is that you used.
 
Sedanman said:
They failed a lot on GM's back in the day. If an HEI GM wouldn't start it was the module 90% of the time. The new modules came with a small packet of dielectric grease. I don't know what the grey goop is that you used.
Click to expand...

Or the rotor got burned through. :D
The grey goop is the same heatsink compound I use in our HEI kits. (for computer processors)
There is white, grey, silicone based, ceramic based and a few others.
They are all thermal paste that transfers the heat from the ECU to the heatsink. (not dielectric grease)
 
As a shop owner, I have replaced LOTS of gm modules over the years, and in comparison the mopar ecu in my truck is orginal, so it's 37 years old.... The main issue, is a lack of quality replacement parts, but this is a issue for ALL brands. Now, you wanna start a ****-storm, just tell someone that a points dist is a extremely reliable device, and watch the comments.
 
Points and only points in any machine functioning in my life.
There is nothing ever created by man in the material world more reliable and simple to service than a points ignition system that receives even the most basic maintenance.
I use them in my daily, I have used them in Top Fuel dragsters, I have played with every type of ignition system you can name, and have never found anything that proves itself clearly superior and worthy of the complication and expense.
Play around with whatever ignition system you choose, but keep a loaded points distributor in your trunk for when.your electronic ignition takes its inevitable **** at the least convenient time and place.
 
replicaracer43 said:
As a shop owner, I have replaced LOTS of gm modules over the years, and in comparison the mopar ecu in my truck is orginal, so it's 37 years old.... The main issue, is a lack of quality replacement parts, but this is a issue for ALL brands. Now, you wanna start a ****-storm, just tell someone that a points dist is a extremely reliable device, and watch the comments.
Click to expand...

Same here, and they were almost all four pin style.
I guess when you sell a billion vehicles with that same part it adds up over the years. :D
I ain't touchin the points over electronic or vise versa statement. :D (like asking what the best trans fluid to use is)
 
TrailBeast said:
It happens, but it's rare.
It's possible that the module was sold as a Standard Motor Products part, but actually isn't also.

Been running the same module on my car for 4 years and thousands and thousands of miles without so much as a hiccup, but I use factory GM 8 pin modules.
One other thing is that 4 pin modules are prone to low voltage death, so you may very well have run across one of these shortfalls.
The 8 pin module is a lot more stable and less prone to voltage issue's, and this is one of the reasons we use them in our HEI Kits instead of the four pin.
(well that and the 8's are a much more reliable and visually cleaner connection setup.) which could have killed your 4 pin from low voltage with the blade connections.
Click to expand...
Do you have a link to your kit? Been thinking of doing that swap but wasn't sure about it
 
dustadude said:
Do you have a link to your kit? Been thinking of doing that swap but wasn't sure about it
Click to expand...

Actually I am not sure you need the kit, as you must already have a coil. (unless you running a canister instead of an E core style)
I might be able to walk you through just swapping over to the 8 pin module if you are ok with that.
I'll PM you about it.
 
I hope everyone understand that thermal compound is to be used sparingly, its a micro gap filler as it will not work as intended if you have a thick layer of it between your heat source and whatever means you have to conduct heat.
 
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HEI modules with bad ground and/or too low voltage can act up and give rough idle.
Also, HEI modules start to heat up quickly at idle rpm's.

Low engine idle-RPM, and almost no charge from a stock Mopar alternator, AND insufficient cooling of the module = Shortened Lifespan.

If they can't get rid of their heat, they'll fail easily.
Had it happen recently. Did have a spare with me, but it was already toast. Great fun...

My current HEI module setup (I have 2 of them mounted under the hood, so I can swap wires in 5 seconds) also has forced air cooling, like in a computer CPU.
I would really like to wire it so the CPU-fan comes on when the module gets over a certain temperature.
Don't have the CPU fans hooked up yet, as they about 1 AMP in power, so they need a seperate power source first.

But I notice the module and its copper cooling block heat up quickly when the engine is idling.

IMG_5184.jpg
 
dano said:
I hope everyone understand that thermal compound is to be used sparingly, its a micro gap filler as it will not work as intended if you have a thick layer of it between your heat source and whatever means you have to conduct heat.
Click to expand...

BigBlockMopar said:
HEI modules with bad ground and/or too low voltage can act up and give rough idle.
Also, HEI modules start to heat up quickly at idle rpm's.

Low engine idle-RPM, and almost no charge from a stock Mopar alternator, AND insufficient cooling of the module = Shortened Lifespan.

If they can't get rid of their heat, they'll fail easily.
Had it happen recently. Did have a spare with me, but it was already toast. Great fun...

My current HEI module setup (I have 2 of them mounted under the hood, so I can swap wires in 5 seconds) also has forced air cooling, like in a computer CPU.
I would really like to wire it so the CPU-fan comes on when the module gets over a certain temperature.
Don't have the CPU fans hooked up yet, as they about 1 AMP in power, so they need a seperate power source first.

But I notice the module and its copper cooling block heat up quickly when the engine is idling.

View attachment 1714998400
Click to expand...

Mine is on a 1/8 x 1.5 x 3 inch flat aluminum plate mounted to body metal.
In AZ if it was going to get too hot it would have already,and this is the newer 8 pin module that doesn't die from lower voltages.
Remember, they normally ran in a distributor that was 180-220 all the time and they were fine there.
 
The one that failed recently for me was a 4-pin DUI performance module.
I'm now using a 7-pin module, but I notice it still gets almost too hot to the touch when I let the engine idle in Drive (550rpm) for a while.
The cooling block also gets that hot so the heat transfer is good.

The module has its own relay so it gets full battery/alternator power @ 14.4v while driving.
 
BigBlockMopar said:
The one that failed recently for me was a 4-pin DUI performance module.
I'm now using a 7-pin module, but I notice it still gets almost too hot to the touch when I let the engine idle in Drive (550rpm) for a while.
The cooling block also gets that hot so the heat transfer is good.

The module has its own relay so it gets full battery/alternator power @ 14.4v while driving.
Click to expand...

Sounds good, though I don't know much about the 7 pin modules personally.
I don't know a reason why they shouldn't be just as good as any of the other newer modules.
 
The 7-pin module was sourced from a stock HEI distributor. Not sure of era.
Do want to hijack the topic, but would you know anything about the 'bypass'-mode on these modules?
Without the remaining pins hooked up, the module will always run in 'bypass-mode'. I'm wondering if this has any effect on its dwell settings perhaps.
 
If you wanted to be Space age you could run a TEC between your HEI and a heat sink. Something like this:

TEC1-12706 Thermoelectric Peltier Cooler (12V, 60W) - ElectroDragon

With the thermal stuff I've dealt with at work air flow is key. Some of my rules of thumb are (I'm far from an expert but have real world experience):
-No thermal conduction going down, remember heat rises. Place your thermal conductor above or vertical. This allows for natural convection.
-Fans help if done correctly. They need a correctly sized intake and exhaust just like an engine. (I got a fun work story on that one)
-Flatness and surface roughness is key to excellent thermal conduction, this is where the thermal past can help if used correctly.
-Use quality materials, copper, aluminum or Diamond if you have some sitting around.
-Avoid barriers like anodization, paint, grease, goo-goo,and boogers. Acceptation is thermal compound.

A good read is Hot Air Rises and Heat Sinks: Everything You Know About Cooling Electronics Is Wrong

Hot Air Rises and Heat Sinks: Everything You Know About Cooling Electronics Is Wrong: Tony Kordyban: 9780791800744: Amazon.com: Books

This is a great book written by a Thermodynamic engineer throughout his career. Its explains in layman terms and is quite funny. Its not a boring engineering nerd book.

Now that my nerd hat if off it seems a lot of electronic ignition modules from Ford to GM are not well made anymore. On my Ford side people who still have Duraspark swear by Motorcraft only or like us, buy two department store ones and pray the second one gets you too the store or home or swap to HEI so you can at least guarantee the store will have one..
 
BigBlockMopar said:
The 7-pin module was sourced from a stock HEI distributor. Not sure of era.
Do want to hijack the topic, but would you know anything about the 'bypass'-mode on these modules?
Without the remaining pins hooked up, the module will always run in 'bypass-mode'. I'm wondering if this has any effect on its dwell settings perhaps.
Click to expand...

As far as I know bypass (called limp mode in the industry here) only locks the timing at a fixed spot so it doesn't move.
The timing was a function of the computer in the car it came out of where the timing wouldn't advance if the computer thought there was a problem somewhere in the system and limit the cars performance.
Once the timing is set on them in a mechanical advance capable distributor they act like a standard ignition module that doesn't have computer control.

This is what I was told when I first started to look into them, and I can't think of any reason the 7 pin would be any different.
 
There seems to be a lot of problems with the HEI. I just drove Route 66 to Santa Monica Ca from Battle Creek MI with a 65 Barracuda slant six with a Chrysler electronic distributor and a MSD Street Fire box. We ended up driving 5889 miles and had the center electrode in the distributor cap started to crumble at about 3000 miles. I changed it in San Bernadino and drove it back to Michigan.
The friend that went with us had a 65 Dart slant six with HEI. He had ECU trouble all the way to California and back, changing multiple ECUs.
I think I'll keep the MSD.
 
Run a MSD cap box,until it dies... Will reload with a large cap HEI, mopar version... (No,I am not afraid of firewall modifications,I massage sheet metal...) The big cap HEI,has too many benefits,in my opine....
 
A photo of the setup would help us comment, but would risk ridicule especially if one of the gomer'ed installations some have shown. One guy had loose wires strung all about with alligator clips. If you don't twist the wires from the distributor pickup and keep them short, you are asking for trouble, like "positive feedback" which could make the ECU self-destruct. Need a good heat sink and solid electrical ground (not rusty sheet-metal screws). The 8-pin GM module is simplest, and what TrailBeast kits. Use the GM cable and coil for simple & robust. But smart to carry critical spares. I have a Crane Cams XR700 (ca 1990's) on my 65 Newport, and lost spark on a Sunday drive. I had a spare points distributor in the trunk, but also a spare XR700 ECU, so the later was an easier swap and quickly got us home. BTW, the Newport has a big trunk (spare carb, ...).
 
HEI = Have Extra ICM (nearby). Since I installed it I was concerned about how hot it gets. The module itself is very hot. The bracket it is on (heatsink attached to bracket GM all in one) wasn't nearly as hot. Maybe the thermal paste is too thick? will see how the replacement does.
 
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