stupid GM HEI conversion

-
M

mopower440

Well-Known Member
Joined
Oct 12, 2014
Messages
797
Reaction score
141
Location
TN.
Cant find my original thread so starting this new one. I got the parts from the junkyard to do the HEI conversion, got the 8 pin module that trail beast recommends. I rigged it all up to make sure it all worked and it did. I decided that i wanted to gut the original mopar box and hide the HEI in it and just use the original mopar plug and all so it looked original. Well, got it all done and it wont spark. Should have known it wouldnt work with my stupid luck. Theres no reason for it not to work but it wont. I even ran a jumper from the negative post on the battery to the module ground to make sure it is properly grounded.. Just really dont understand why it wont work through the factory wiring and plug.. pisses me off as ive been wanting to get this done for a month and finally do and it aint gonna work!
 
Thanks. I think im just so pissed that i cant think straight, probably looked right at the post and didnt see it.
 
Just step back, take a breath and relax. Look at the diagram. There aren't many wires and connections. You'll get it.
 
RustyRatRod said:
Just step back, take a breath and relax. Look at the diagram. There aren't many wires and connections. You'll get it.
Click to expand...

Thats the thing, its wired correct but wont work. Its like it doesnt like the factory wiring and plug or something.. like i said, i just set all the parts on top of the engine and wired it all up just to try it out and it worked and ran nicely..
 
What brand HEI module is it? Is it the used one from the junkyard? Is it a cheap big box replacement? They can be pretty sensitive. You may have shorted it out somehow.
 
Personally I think its neat that its possible to hide the little gm module in the mopar box for aesthetics....but in my experience I have changed more gm hei modules in my chevys, than I have ballost resistors in my mopars. Mopar and gm electrical ignition is about the first thing I toss in the trash in place of an ignition box. This HEI module conversion stuff is pinching pennies that end up costing dollars. If you dont want to see the box, hide it under the dash. But anyways...I have had good luck with these as an inexpensive option. Good luck
http://m.summitracing.com/parts/sum-850610
 
RustyRatRod said:
What brand HEI module is it? Is it the used one from the junkyard? Is it a cheap big box replacement? They can be pretty sensitive. You may have shorted it out somehow.
Click to expand...

Its all genuine GM stuff. And like i said, when i got it home from the junkyard, i tried it all out and the car ran very nicely with it..
 
I think I am the first to suggest the 8-pin HEI module, but not my idea. Read all about it on the Megasquirt site. TrailBeast decided to kit new parts to sell, which is great and convenient for many. Long before, SlantSixDan and others showed the 4-pin HEI use. The 8-pin is easier since a GM cable plugs module to coil, leaving just a few wires to hook to your car.

Why not back up to what worked? Assemble as you did initially and see if that still works. Since you didn't, and are all pissed off, it sounds like you are new to developing things (not so easy when you try it yourself). If it still works, you then know you didn't fry the HEI module.

It will need a good heat sink to avoid frying it. GM bolted it to aluminum and you are bolting it to thin steel, which is a much poorer heat conductor. You also must use thermal grease. It also needs an electrical ground to the car's body. It also needs full 12 V, so bypass your old ballast resistor. I assume you kept the 2 pickup wires from the distributor the same as before. They must be twisted and not run near the spark plug wires, and don't change the polarity from what worked.
 
BillGrissom said:
I think I am the first to suggest the 8-pin HEI module, but not my idea. Read all about it on the Megasquirt site. TrailBeast decided to kit new parts to sell, which is great and convenient for many. Long before, SlantSixDan and others showed the 4-pin HEI use. The 8-pin is easier since a GM cable plugs module to coil, leaving just a few wires to hook to your car.

Why not back up to what worked? Assemble as you did initially and see if that still works. Since you didn't, and are all pissed off, it sounds like you are new to developing things (not so easy when you try it yourself). If it still works, you then know you didn't fry the HEI module.

It will need a good heat sink to avoid frying it. GM bolted it to aluminum and you are bolting it to thin steel, which is a much poorer heat conductor. You also must use thermal grease. It also needs an electrical ground to the car's body. It also needs full 12 V, so bypass your old ballast resistor. I assume you kept the 2 pickup wires from the distributor the same as before. They must be twisted and not run near the spark plug wires, and don't change the polarity from what worked.
Click to expand...

The module is bolted to an aluminum heatsink with thermal paste between them, and hidden inside the gutted mopar box, and yes it is grounded to the firewall, i even ran a jumper wire from the module to the negative side of the battery. The ballast is bypassed and i have 12 volts to it. No, im not new at this stuff, i built this whole car from the ground up. Im just pissed because it all worked untill i ran it through the original wiring and plug to the mopar box and was excited about it..
 
Im assuming you stuck with the stock harness for the stock look as well....

I did this conversion also and hid the module in a Mopar box. Love the look of it! Make sure that your wires are soldered very well to the pins on the Mopar ECU. When I was assembling everything the one thing I notice when putting it together, was that the wires were tight in the box.. Make sure that they didnt break off inside the box at the pins. Also make sure that when you connected the mopar wire harness to the box that the pins didnt push into the box and not making a good connection on the harness.

Just a couple of things to look for.. The above things are a couple of things that Im worried is going to happen when Im out driving my car and then Im screwed and stuck on the side of the road.
 
johnnymac2k6 said:
This HEI module conversion stuff is pinching pennies that end up costing dollars. If you dont want to see the box, hide it under the dash. But anyways...I have had good luck with these as an inexpensive option. Good luck
http://m.summitracing.com/parts/sum-850610
Click to expand...

Actually it's very efficient,,

Tell me,, when your unit breaks down on the street,,, do you tow it home?..
how long do you wait to get a new part..??

Can you walk to the closest auto parts supplier,, and buy that summit unit?? for under $20.

You can the HEI.. lol

hope it helps
 
mopower440 said:
The module is bolted to an aluminum heatsink with thermal paste between them, and hidden inside the gutted mopar box, and yes it is grounded to the firewall, i even ran a jumper wire from the module to the negative side of the battery. The ballast is bypassed and i have 12 volts to it. No, im not new at this stuff, i built this whole car from the ground up. Im just pissed because it all worked untill i ran it through the original wiring and plug to the mopar box and was excited about it..
Click to expand...

ok, i swapped out the module and it now works. Starts up and runs fine, BUT, the spark is NO stronger than what the mopar box could do. If i undo the coil wire at the distributor and have someone crank the engine over, it only produces a yellow spark and i can only get the cable about an inch away from the block before the spark dissapears. From past GM experience, and from watching trailbeasts video, this thing should produce a blue spark and be able to jump MANY inches to ground...any ideas..?
 
HMMM, ok, so after i got it all up and running through the mopar wiring and plug and the module mounted and hidden inside the mopar box, i decided to go in the house to use the bathroom and think about why the spark is so weak..I come back out and she wont start! I pull the coil wire and no spark!! Damn, thought i burned up this module also, but its not! I took the first module, that i THOUGHT was burned up and rigged it all up like i did the first time when i brought it home from the junkyard and BOOM!, Big fat lightning bolt spark like in trailbeasts video! SO, the problem seems to be the length of wire. For some reason, if i run it through all that original mopar wiring, it aint got enough to fire it and the few times it did, it was a very weak yellow spark. Yes, this obviously makes no sense because trailbeast had some length to his wires also, but on my pig, it wont work. I dont understand it and it makes me mad after digging all the guts out of the mopar box and having the box painted up and fabricating an aluminum heatsink for it and all, really makes me mad. I guess now if i want to run the GM crap i will have to buy that little mount that guy sells that mounts the module right up under the distributor so the wiring doesnt have to be very far. Again that sucks because that mount he sells is for the 4 pin module and i have already bought 2 of the 8 pin modules. Just dont understand..
 
Is it poss that something is getting pinched inside the module,, take it apart,, and let all the wiring hang loose, then try it..

Sorry if I missed it,, ballast resistor bypassed.??
 
inertia said:
Is it poss that something is getting pinched inside the module,, take it apart,, and let all the wiring hang loose, then try it..

Sorry if I missed it,, ballast resistor bypassed.??
Click to expand...

Ya ive tried that and the ballast is bypassed.
 
Something isn't right.
My wires are about 30 inches long, not twisted and I don't have a problem one with mine.
Going on 2 years now, and the only problem I have EVER had with it was a broken solder joint from unhooking and hooking it back up from testing other people's kits on my car.

I would suspect low voltage/amperage issue's at the coil itself (which also powers the module) after going through the coil.

Try powering the coil directly off the battery pos and see what it does.
(everything else will work the same except you will have to pull the coil wire from the battery to kill the engine)


OH, and this isn't very confidence building about that summit CDI unit.

Quote,
I used this box on my 650whp Civic over two years ago with great results. I loved it. So when the time came to upgrade the ignition on my current car I logically went for it. Hooked everything up, and no spark. The LED lit up for a second when I first put the key to the on position however there was no LED upon cranking telling me it was sending spark. I then checked and double checked my wires and their voltages/currents with a multimeter. I then concluded that it was bad. Later I noticed that many others in the Honda community have been having problems with these recently as well. Some were bad out of the box like mine, others are working fine for 50 miles then "hiccuping" like crazy. It seems to be only on the recent boxes sent out that I see the trend. Maybe the manufacturer was changed (it is rumored it was originally Mallory that made them) or just some quality control issue has come up. To play it safe I would opt for the Mallory 6852 box. It's 20 dollars more and hopefully more reliable. I hate to write a bad review on something but I also don't want people going through the same thing I did wasting time and effort. I hope Summit gets these issues resolved because they were awesome boxes for the price back when they worked. If the problem continues I hope that Summit does the right thing and starts not selling them....

End quote.
 
That's the only negative review on that unit. I thought about doing the GM swap but it does not provide an rpm limit. The summit box does for under $150.
 
Idaho said:
That's the only negative review on that unit. I thought about doing the GM swap but it does not provide an rpm limit. The summit box does for under $150.
Click to expand...

One, but about apparent multiple instances (but who knows really unless we experience it personally, right?

I love the HEI fire but not permanantly attached to the module, so I have been thinking to use the E-coil with the Pertronics 3 module that has a user settable RPM limiter.
(I see they have them for us now for V8 only if you click the "Buy" link.) I may change to one of these now even though I already have a brand new Pro Comp 2 stage.

This is the module with the RPM limiter http://www.pertronix.com/prod/ig/ignitor3/default.aspx
It's been awhile since I looked so if I got a detail or two wrong that would explain it. :)

CRAP :) I see they changed how the limiter works in the 3 version now.

The older one had a single wire than ran into the cab with a button to ground it, and you would run the engine at 50% of desired RPM limit and press the button.
Then upon turning the ignition on it would bounce your tach to that RPM without the engine running for verification of your rev limit.

Dammit, I liked the old one better.

Maybe I'll just start working on building inexpensive plasma fired ignition kits.:D
 
You must log in or register to reply here.
-

Back
Top