HEI in Mopar ECU casing

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Ok I will do the heatsink then guys. Thanks for all the input. It'll be a while before I post pics of it (currently rebuilding steering box and repainting intake and exhaust manifolds) but I will get to it.
 
well, mine has been working fine for 2 years now. I havent ran it for a few months so today i go to start it and nothing.. No spark. I tried my spare GM module and also my other GM coil and still nothing. I have power to the module and coil but it just wont fire the plugs...? Not sure what is wrong. was working fine last time i drove it..
 
mopower440 said:
well, mine has been working fine for 2 years now. I havent ran it for a few months so today i go to start it and nothing.. No spark. I tried my spare GM module and also my other GM coil and still nothing. I have power to the module and coil but it just wont fire the plugs...? Not sure what is wrong. was working fine last time i drove it..
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Ground at the module is important too. The module pulls the coil - to ground too charge coil. It also needs trigger signal from pickup coil. The pickup connectors can be troublesome.
 
KitCarlson said:
Ground at the module is important too. The module pulls the coil - to ground too charge coil. It also needs trigger signal from pickup coil. The pickup connectors can be troublesome.
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Turned out the pick up coil gap needed to be tightened up. Starts right up now. I would love to know how the heck the gap just mysteriously widened while it was sitting in the garage. It was fine last time i drove it..
 
Perhaps it is cooler now, the signal output is proportional to engine speed. An engine cranks slower, and the output may fall below trigger level. An engine cranks around 200 RPM, and idle around 600+, so engine runs, but have trouble starting. At 600 the signal is 3 x that of crank.
 
Major Question! How in the world are you guys getting away with running the GM 8 pin module? I have 4 genuine GM 8 pin modules and every one of them add 10 degrees of advance at around 3500 rpm and make it detonate like crazy! Got to be more than a coincidence that 4 different 8 pin modules add this advance..are you guys sure yours isnt doing this also?
 
Well, after researching the internet literally ALL day, i have figured this out and i should have already known the answer since my boat with 350 GM engine uses this same setup. These 8 pin modules have 10 degrees advance built into them! If you are using this module on a carbureted engine, you have to put the spark timing into bypass mode to set the initial timing so it WONT try to advance the timing, and that requires jumping to pins together and hooking another pin to 12 volts. To verify this, i tried it on my car and sure enough, that stopped the advancing problem! The catch is, you cant leave it plugged up into bypass mode because it is setup to where you have to start the engine, then shut it off, connect the bypass wire, then start it up again to set the timing. once you turn off the ignition, it wont start up again until you have removed the bypass jumper and started the engine without it, then you can hook it up again. You could use it on a switched 12 volts but im not going to bother, i will just get a 4 pin module and be done with it. I happen to have the 4 pin plug that is not used on the 8 pin module when using these with our old cars so i made the ESC bypass with it to verify what i read (and already knew and forgot) and sure enough! Guys running the 8 pin: i bet if you watch it with a timing light, you are getting extra 10 degrees of advance after around 3-3500 rpms. It drops back out at WOT but makes mine ping. Hope this helps!https://forums.iboats.com/filedata/fetch?id=6932127
 
Wow, that's pretty crazy! I still haven't done this mod but plan to this winter but with 4 pin. I didn't even consider the 8 pin lol.
 
jrc4y4 said:
Wow, that's pretty crazy! I still haven't done this mod but plan to this winter but with 4 pin. I didn't even consider the 8 pin lol.
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yup, it all makes sense now too because I have an old 1986 boat with a 350 chevy engine that originally had points. I upgraded it to the 9 pin distributor system as that's what was on the newer boats and indeed that's how the engine gets its advance is through the 8 pin module. The boat is carbureted and that 4 pin plug for controlling timing is not used on the boat either, but the timing does indeed advance on its own on the boat and I remember when I installed it having to plug the jumper into the 4 pin hookup to bypass the advance to set the initial timing according to the boat manufacturer. SO, I tried the same jumper trick on the car and that stopped the advancing, But like I said, you cant just leave the jumper plugged up because it wont start with it hooked up all the time. SO, I got the 4 pin and will be switching it over.
 
Sounds like a good call then. I would have never known that. I think I'm going to put the 4 pin under my hollowed out orange box and then hardwire behind the ballast resister so it looks stock but isn't.
 
jrc4y4 said:
Sounds like a good call then. I would have never known that. I think I'm going to put the 4 pin under my hollowed out orange box and then hardwire behind the ballast resister so it looks stock but isn't.
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That is EXACTLY how I did mine! I think its cool how it keeps it original looking! The only reason I did the 8 pin originally is because they are all over the junk yards.
 
Got the 4 pin installed today, all good now! No more added advance getting thrown in..Now to buy a spare module to carry with me. I have 4 of the 8 pins for back up. Wish i could trade a few for some 4 pins.
 
I don't know if they vary the 10 degrees rpm-based. I thought they just ran on 10 deg.avance if the reference pin isn't connected.
They then really should be used with ECU controlled timing and a fixed distributor. I'm using a 7-pin HEI module in my Dart with a MegaSquirt 3X.
 
Newbee and first post.

I am thinking about doing this mod first on my 78 LRT' 410 ci Magnum stroker project and later on a few other Mopars like my/son' 65 B-Cuda and his 74 Dodge D200 with a 68 383.

Every Mopar that I have had that was points ignition got converted to Electronic ECM. Over the years I have had about 5 stockish ECM's and a few Chrome box's fail. The 1978 Orange box is still working but.... Too bad I scraped all those burnt out ECU's.

I will do the GUT the ECM potting and build an aluminum plate under the ECM box then strap a 14 Gauge wire on the ballast resistor so it all looks 100% MOPAR.

I bought 2 CHEAP 4 pin HEI modules as the test for $21 for 2. If this works then I may do the upgrade to the Pertronic Rev limiter unit for $85.

I am real good at electrical stuff, 20 years US Army telephone systems and 18 years GTE-Verizon telephone repair. Out of all my expensive test gear including an 'O'scope..., my #1 go to test piece for automotive troubleshooting is my simple 12 volt test light. If its bright then don't worry about it but if dim, check for resistance faults with a Fluke VOM meter... KISS
 
Yep putting the GM 4 pin inside the old chrysler ECM box is a great idea if your car is already electronic ignition. Once its installed, it's a plug n play sort of deal. I used a mount plate by www.designed2drive.com for my 67 since I wanted to keep it appearing somewhat stock. I gutted a stock ballast resistor and soldered a 12G wire across, then filled in the resistor cavity with the wire using 5 minute epoxy.

Theres guys on fabo that are gonna Phoo Phoo you about using the GM module. I had been ridiculed by a few of em posting 4x4 camaro pix and people with billy bob teeth, and calling it a science project looking install. However you can use one and make the system appear stock, have faster cold starts, better idle quality, better acceleration, better fuel economy using the HEI over the stock mopar electronic boxes. I believe the stock GM modules are just fine up to 5,500 RPM. Above that they start to break up.

Also use either a GM E coil or if stock appearing is your game, spec out a pertronix ignitor lll cylindrical oil filled coil designed with a .32 ohm primary and a 45,000 V output. Pix of mine I made a 90° adaptor going from the mopar pickup to the GM module plug.

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My 78 LRT has a 1978 date coded Warrenty 360. The first owner said in the first 6 months it was in shop 3 times for oil leaks and on the 4th time the Dodge dealer ordered a new cop car 360. So not a numbers matching truck. But I am putting a 2008 (?) 5.9 Magnumn with Edelbrock RPM aluminum heads and shorty headers so it does not look stock now.

If this works out I will do a second for our 1965 B-cuda. I converted it to ECM back in 1987 or so.
 
OK, I took my last failed 4 pin ECU and submerged it in boiling water a few times and was able to pry out all of the epoxy potting. Under was a PCB with what Kind of looked like what an HEI module looks like under its plastic. It was embedded in silica sand and epoxy too. Guess what? NO wires going to the 'Transistor' Cap mounted on the aluminum heat sink. There is a plastic sealing ring under the cap but not drilled for wires. Its a dummy.
We got this last one from Autozone. Duralast CR109. "Duralast products are engineered and manufactured by Wells Vehicle Electronics"
 
They stick a dummy transistor on there to make it "look" like OEM. The only thing that aftermarket box is good for is the housing with fake transistor and wiring plug. Gut it, make a backing plate, and mount an HEI module inside it, fake transistor and all. No one will ever know.
 
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