gm hei ignition help

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mr.318

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Okay i needed a new ecu and fiugred i'd install new wire.I see some here use it i got the the insts, from alink on here by golduster.Anyway now no fire no start.The hei is grounded the only wire i reused is the brown one to coil took ballast out put jumperwire in ballastwire to ballastwire as insts.say i have power to + side of coil key on and while trying to crank is that right? anybody done this that can help me out thanks
 
If I recall correctly, the HEI module should only be grounded by its connection to the housing (screws mounting it). I may be off as it's been a while, but a connection to chassis ground from any of the (presumably) 4 terminals will prevent the module from operating.

Someone that's more familiar with this particular application may have a more accurate diagnosis. I've only dealt with them on GM stuff and my brain is running on fumes.
 
Yea it says to ground it but like you say with the mounting screws i just checked the screws with testlite
 
I had to pull up some schematics to keep it all straight in my head. I'm looking to make sure I'm on the same page.

Terminal B should be connected to both the positive side of the coil and the wire that's hot with ignition 'on'. Terminal C should go to the negative side of the coil. Terminals W & G should go to the trigger (magnetic pickup) which serve the same function as terminals at 11:00 and 8:00 on the Mopar box. The trigger connections shouldn't be picky about polarity.
 
yea thats the way i got it just not sure bout the feed wire to coil the directions said to use blue wire from ballast but the brown ones hot it was converted from points before i got it the wireing was a mess thanks
 
Hmm. Sounds like the wiring is schematically correct. If there are no errant strands of wire finding a ground anywhere strange and the module is getting at least 8 volts (I think) at Terminal B, it may be something goofy like a bad module. I used to buy them two at a time to save a trip into town (and/or to keep a spare in the glove box). Faulty new ignition parts happen occasionally and they drive one mad.

It may be worthwhile to disconnect the battery and confirm a lack of continuity between chassis ground and each wire on the module. Possibly swap in a known good coil to shorten the list of possibles.

I doubt it's causing this problem as it hasn't had a chance to build heat yet, but a healthy dose of heat sink grease is vital to the module's longevity. Heat kills more of them than anything.

Now, I must zonk out. I hope the root of the problem avails itself soon.
 
I went and bought a acell gei just morning still no start switched wires going to dist. no l;uck let me change the coil i got 3
 
The only power connection an HEI needs is the B+ to the unit via the original power wire and bypassing the ballast resistor is the correct thing to do. It gets ground from the engine block. If you have B+ going to it the problem can only be one of 3 things. Either a bad module, coil, or pickup. Since you changed the module it has to be one of the others as it's unlikely you got another bad module. The way I used to test the module and coil was to take the cap and rotor off leaving the coil hooked up and unhook the 2 prong connector from the pickup going to the module and wet a finger and touch it across the module connections where the pickup plugs in. This simulates the pickup firing. Of course you need the key turned on and keep your hands away from the coil output cause HEI will hurt you. When you touch your finger across the module input you should hear a click sound coming from the coil firing. If you do hear the click the pickup is faulty. If no click is heard it's either the module or coil. You can also check the pickup with an ohmmeter. It should have approx. 600-700 ohms.
 
Well changed the coil and it cranked but when i put it in gear it surges and dies tried swaping the wires going to dist, and it won't crank at all that way + it wouldn't crank at all with the accell hei took it back they checked it said it was bad got another one still won't crank with the new one but will crank with the gp brand one ? i even took my coil feed off put a hotwire from bat on coil cranks then dies when put in gear i'm lost
 
Contrary to all the stuff on the web you can't eliminate the ballast resistor unless you purchase coil that is specifically designed to be used without a ballast resistor.
 
Yea long as you have a per.coil or one from the leanburn ign. your good without ballest, Not beliveing this 3 new hei modules.bad in a row 2 accells,that wouldn't even start and one g.p.t.than barley run, Put a new napa one on she runs good.All that trouble with new parts no pride cheaplabor.I seen on another post that the plug gap should be @ 40 with this setup is that right ? I noticed that it's idled alittle higher and starts rightup is it puttin out the same as the mopar system ? thanks all
 
Mine is hooked up like this
100_0539.jpg

MVC-004F.JPG
 
dgc333 said:
Contrary to all the stuff on the web you can't eliminate the ballast resistor unless you purchase coil that is specifically designed to be used without a ballast resistor.
Click to expand...

Dave your right when talking about many ignition systems but if you read his first post you'll see it's a GM HEI type ignition. No GM HEI system used a ballast resistor. All coils designed for the HEI are designed for no ballast resistor. If he would have left the stock ballast resistor in place it might have run for a short time but would have burned it up pretty fast because the HEI draws approx. 5-7 amps @ 13 volts equals 65-91 watts and the stock resistor won't dissipate that much heat.
 
mr.318 said:
Yea long as you have a per.coil or one from the leanburn ign. your good without ballest, Not beliveing this 3 new hei modules.bad in a row 2 accells,that wouldn't even start and one g.p.t.than barley run, Put a new napa one on she runs good.All that trouble with new parts no pride cheaplabor.I seen on another post that the plug gap should be @ 40 with this setup is that right ? I noticed that it's idled alittle higher and starts rightup is it puttin out the same as the mopar system ? thanks all
Click to expand...

Man what a deal having to go through that many to find a good one. So much for quality control.

You can try gapping them at .040 and see if runs better. Sometimes they do and sometimes they don't. I read a tuning article yrs. ago that said to gap them .005 wider at a time and test run it in the 1/4 after each gap change. When you finally reach the point when it slows down close the gap up .010 and that's the point of best power. I tried it on my Dakota and it slowed down at .055 so as per their recommendations .045 is best power.
 
fishy68 said:
Dave your right when talking about many ignition systems but if you read his first post you'll see it's a GM HEI type ignition. No GM HEI system used a ballast resistor. All coils designed for the HEI are designed for no ballast resistor. If he would have left the stock ballast resistor in place it might have run for a short time but would have burned it up pretty fast because the HEI draws approx. 5-7 amps @ 13 volts equals 65-91 watts and the stock resistor won't dissipate that much heat.
Click to expand...

The GM HEI module is no different than the mopar ECU, it is a switch to ground that opens and causes the magnetic field in the coil primary to collapse and creat the high voltage in the secondaries. The module itself may draw 5-7 amps which I am quite sure the mopar ECU does also but the power to operate it does not go through the ballast. The ballast is to limit the current flow through the coil.

GM did not use a ballast but they also designed the coil it to operate without one. If you use a stock mopar coil or an after market coil that is designed to be used with a ballast without a ballast you will allow to much current to flow through the coil causing it to run hot at low rpm's shortening it's life expectancy. This is true whether it is a GM or mopar ECU. The original poster is just replacing the mopar ecu with the GM HEI module, no mention of using a HEI compatible coil and from the picture he later posted it looks like an Accel Super Coil which is designed to be used with a ballast.

A ballast resistor by definition is a variable resistor where the resistance increases as it gets hot. This characteristic limits the current flow through the resistor. It is also this characteristic that allows more current flow at high rpms, because it does not get as hot, to offset the natural drop off in the coils output do to the decreasing time current is flowing through the primaries. It also allows for completely bypassing the resistor in the start mode to get more output from the coil when starting the engine.
 
dgc333 said:
The GM HEI module is no different than the mopar ECU, it is a switch to ground that opens and causes the magnetic field in the coil primary to collapse and creat the high voltage in the secondaries. The module itself may draw 5-7 amps which I am quite sure the mopar ECU does also but the power to operate it does not go through the ballast. The ballast is to limit the current flow through the coil.

GM did not use a ballast but they also designed the coil it to operate without one. If you use a stock mopar coil or an after market coil that is designed to be used with a ballast without a ballast you will allow to much current to flow through the coil causing it to run hot at low rpm's shortening it's life expectancy. This is true whether it is a GM or mopar ECU. The original poster is just replacing the mopar ecu with the GM HEI module, no mention of using a HEI compatible coil and from the picture he later posted it looks like an Accel Super Coil which is designed to be used with a ballast.

A ballast resistor by definition is a variable resistor where the resistance increases as it gets hot. This characteristic limits the current flow through the resistor. It is also this characteristic that allows more current flow at high rpms, because it does not get as hot, to offset the natural drop off in the coils output do to the decreasing time current is flowing through the primaries. It also allows for completely bypassing the resistor in the start mode to get more output from the coil when starting the engine.
Click to expand...

Dave your right the module does work the same way as a Mopar module works and draws similiar current. And yes your correct the ballast does limit current flow through the coil when wired like a Mopar is. But if he's using the Davis Unified HEI system like I assume (maybe I'm wrong there) the original ballast resistor is in the wrong place in the circuit. That's why it needs bypassed.

If you look again at the picture shown that you refered too you'll see that it was not from the original poster but someone else showing his setup.

Since the original poster said he has a GM HEI system I assumed that he has one of the Davis unified systems which is the only GM HEI system for a Mopar I've seen. :dontknow:

Maybe MR.318 can verify which system he's actually using.:-k
 
No i'm just useing a gm module, But dave theres a couple post on here one guy said he'd been running this setup 5 yrs. no ballast no problem.I also read on another site 2yrs stockcoil no ballast like i said i read this so i don't know.My coil is a chrome superstock i tried it with the ballast it will start but will not idle.I'm thinking it would need a small ballast close to coil like a accel one.So do i need one or not??
 
I am not sure about using that module in a conversion ..but on a gm hei the terminal you have marked as number one is the tach drive .it doesnt go to battery neg. if you dont have a tach for hei then you may not need to use it at all, .also ...aftermarket coils that are mopar specific may very well need a ballast resistor, I just replaced my accel coil in my dart and it even came with a specific resistor for the accel coil . but i also have a dual point dist. like i said i am not sure if this applies to your application or not ....but it sounds to me that you are burning up the modules. hope you get it straightened out....
 
There are coils out there that are designed to be operated without a ballast resistor. If you are using one of those then you do not need one with the GM HEI module or one for a mopar module either.

You can get away for a long time without a ballast resistor with a mopar ecu too. But, not running one when it's designed to have one increases the likely hood of a failure dramatically.

I might make a decision to reduce reliability if it meant an increase in performance but leaving out the ballast resistor does not provide any performance increase so I fail to see an advantage to doing it. I know folks complain about the reliability of the ballast resistor but a road side break down due to ballast failure is so much easier to deal with by either plugging in a spare or by bypassing it all together to get home.

I notice 70Valient's wiring diagram shows the module getting it's power from the coil plus. If you are using a ballast this will reduce the power to operate the module and likely could cause all sorts of operating issues. I would recomend the power to operate the module come from upstream of the ballast as it does in the stock mopar electronic ignition.
 
That's one of the sites that talks about elminating the ballast resistor with no mention of the need to have a coil that is specifically designed to operate without a ballast.
 
I notice 70Valient's wiring diagram shows the module getting it's power from the coil plus. If you are using a ballast this will reduce the power to operate the module and likely could cause all sorts of operating issues. I would recomend the power to operate the module come from upstream of the ballast as it does in the stock mopar electronic ignition.
Click to expand...

That is correct on mine the module is getting its + and - from the coil, my ballast resistor has been eliminated.
I put the pic of how it is actually setup on the car since I realized the coil could be confused for a battery.
 
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