Electronic Ignition

[belmateo]

Hey Guys, just want some last minute input on this if you have time. I want to upgrade my 69 vert GTS clone to a Chrysler distributor and have read about using GM parts of all things. Have already read what others like slant six Dan have contributed. So here is my question, do you really get a hotter spark with the HEI style or is there really not much of a difference with the Mopar orange or chrome control box?
Thanks as always I truly value your opinions.

 

[powerwagonpaul]

i can tell you this, using the HEI i passed smog with last years plugs. did nothing to it this year and passed smog first time. both the valiant with a slant six and the powerwagon with a 318. i am sold on HEIrayer:

 

[belmateo]

good point

 

[67Dart273]

Mine APPEARS to be hotter but I'm not sure that it really IS. I no longer have access to the sophisticated test gear that would be necessary to evaluate this. It's much MORE than just spark voltage or the casual appearance of the spark. It has to do with spark ENERGY (power if you will) as well as the rise and decay times of the pulse

For example, YEARS ago (70s) when there were a couple of aftermarket CDI add on units kicking around, there was speculation that even though these develop a VERY sharp and high voltage spark, UNDER SOME conditions, they might not develop the ENERGY to punch through some fouling conditions

But for me, a "hotter spark" was not really the issue. In my case, the coil that I happen to have seems happy with an HEI and no ballast resistor, so the wiring is quite simple. It is small, so to carry a spare is easy, and with all the do-de-do about some aftermarket Mopar ECUs leaking resin, etc, I'm happy with the HEI.

 

[belmateo]

Okay, so how can I wire it under the hood and keep it clean looking without worrying about the unit getting too hot?

 

[KitCarlson]

A thick aluminum block is often used to mount the module to the bottom of the distributor top casting. The GM module controls the dwell timing such that ballast is not required. It may save energy, releasing a bit of HP. It also may make the coil run cooler.

The mopar box starts the coil current too early and the increasing current is limited by the ballast resistor. The GM module predicts the dwell time prior to spark, such that the current limit happens just when the spark is desired.

 

[moparlover]

but you can tool around town just fine with the mopar electronic + orange box
~$225 there is one for LA engines one for B and one for RB
P3690426 LA 273 318 340 360
P3690427 B 383,400
P3690428 RB 426, 440

 

[67Dart273]

Okay, so how can I wire it under the hood and keep it clean looking without worrying about the unit getting too hot?

Some will scoff, but I mounted mine direct to the firewall. Someone had already punched a couple of holes in my (67) firewall to the pass. side of the wiper on a flat spot there, for an ECU conversion. So I used one of the holes they drilled and made one more.

I broke off a locating tab on the back of the module so it lays flat, used the supplied grease, and screwed it down. Two wires to the pickup coil. They ARE polarity sensitive, and the rotor will be "out of phase" if it's wrong.

One more wire to coil neg, one last wire to coil pos, and the power lead, and you're done.

 

[powerwagonpaul]

i used an old computer heat sink for the truck. mounted it to one of the coil bolts. for the car slant six i made a nifty bracket that mounts to the alternator bracket, puts the module right between the dizzy and the coil where it needs to be wired.

 

[4woody]

I haven't got mine running yet, but I mounted the module to a piece of 1/8" aluminum about 3x4", which itself is bolted to the intake just under the coil: Will this give it enough cooling?

How hot is too hot for the HEI module?

 

[67Dart273]

Personally, I'd get it off the engine if possible.

 

[powerwagonpaul]

I haven't got mine running yet, but I mounted the module to a piece of 1/8" aluminum about 3x4", which itself is bolted to the intake just under the coil: Will this give it enough cooling?

How hot is too hot for the HEI module?

that should be fine, GM put them inside the dizzy with NO airflow:burnout:

 

[BillGrissom]

I suggest the "GM 8-pin" HEI module and "GM external coil" since it has connectors to keep everything clean. Search my recent post on a junkyard trip for more info. I will mount on a CPU fins I had from an old PC, and put on the fender to get out of the nasty grease zone where the distributor sits. The advantage over the Mopar module is you get rid of the ballast, can use an E-core coil, is more reliable and available, and probably more energy.

To realize the better combustion potential, you must open your spark gap to 0.060" (reduce to 0.050" if it mis-fires on WOT). For even more spark, I have an MSD Stacker module I got cheap on e-bay. It adds to the ignitor, giving multi-spark. No longer made (not Stacker 8 which is for new COP engines).

 

[powerwagonpaul]

I suggest the "GM 8-pin" HEI module and "GM external coil" since it has connectors to keep everything clean. Search my recent post on a junkyard trip for more info. I will mount on a CPU fins I had from an old PC, and put on the fender to get out of the nasty grease zone where the distributor sits. The advantage over the Mopar module is you get rid of the ballast, can use an E-core coil, is more reliable and available, and probably more energy.

To realize the better combustion potential, you must open your spark gap to 0.060" (reduce to 0.050" if it mis-fires on WOT). For even more spark, I have an MSD Stacker module I got cheap on e-bay. It adds to the ignitor, giving multi-spark. No longer made (not Stacker 8 which is for new COP engines).

Bill, how do you wire the 8 pin module? i have not seen diagrams for that module. and what are the advantages over the 4 pin unit?

 

[BillGrissom]

powerwagonpaul,

The best info I found is www.megamanual.com/ms2/GM_7pinHEI.htm.

One factory GM cable (~1 ft long, 2-wire) goes from the HEI to the "GM external" coil. It has connectors on both ends.
The coil has another connector for ign (+12V pink) and a tach signal output (wht, if you want).

Run a ground wire to the HEI module mounting bolts.

Connect the 2 wires from your distributor pickup to the P & N terminals on the HEI module via GM connector. Of course, you need a later Mopar electronic distributor, though I have heard of upgrade kits for older distributors.

I think you can leave the 5-pin connector open if not using computer control of timing, though there is a ground wire that might need to be connected. In that case, your existing weights and vacuum advance control the timing and the HEI just replaces a Mopar box.

Raid the junkyard, mainly for the connectors. You can buy all other components new, if desired. Look for any 85-95 GM truck or V-8 GM cars to ~93, all with TBI (some V-6). The coils come with various brackets. I have 2 types, but wish I had one I saw in a photo that sits the coil on its side, which is better for my 225 engine.

I am just now installing HEI on my 64 slant six. I chose it since my other two 60's cars have Crane XR700 ignition. I haven't fired yet, so don't accept above as gospel. I must determine correct polarity for the pickup wires. HEI fires off a positive to negative transition, which I will check on an O-scope. Many people just try both polarities and choose the one that fires near the timing mark. An issue even with GM cars since their pickups vary in polarity (GM engines spin backwards? or maybe distributor rotation varies like Mopar SB vs BB). The HEI module requires a VR pickup like 70's Chrysler distributors. Later Hall-effect pickups won't work directly, but might if you provide 5 V power and capacitor coupling to shift the signal down so it crosses zero.

I will later try the Holley Commander 950 on some of my cars. It has a direct connection to GM 8-pin HEI.

While on a JY truck, you might also grab the knock sensor (water jacket drain plug, passenger side, looks like oil pressure switch) and processing module (ESC, 5-wire flat module usually on intake manifold or on firewall passenger side). The Holley Commander and other controllers can be configured to respond to the knock signal, or you can just wire it to a warning light.

 

[nqkjw]

Use a 4 pin module either Bosch BIM024 or GM IM112
I've got them on my slant 6 1967 ute,440 1970 challenger,318 1972 Dart Swinger,413 1960 Imperial and blown 360 magnum 2000 Ram.
You'll notice the difference IMMEDIATELY.
They just start so much easier.

Don't forget to bridge the ballast and use a full 12v coil.