Mopar to GM Ignition conversion

dkamp

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I have a 318 with a two wire Distributor without points. I'm currently running the Mopar ignition (4 wire Orange Box, 1 Ballast resistor, and factory Oil filled coil).
I want to change to a GM HEI system with no Ballast, but have a few stumbling blocks that I need to overcome first.
If I go to a Junk Yard and locate a 85-95 Chevy S10 and take the 4 pin E-Core coil, and the HEI module (ACDelco D-1906 (4 Pin)), all the needed wire connectors and the coil wire, then make all the correct wiring.
Is the Donor truck OK to use or can you suggest a coil HEI combo that is better?
Please offer a few Make/Model/Year donor vehicles.
Or quote E-core coil and HEI part numbers.
If I can only find an 8 pin HEI module, can I just only use the 4 wires like the D-1906? using this diagram?

1672539482131.jpeg


Thank You DKamp
 

Aspen500

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You could also look at a Davis Unified Ignition (DUI) HEI ignition. Basically a drop it in and done set up. Have one on my Aspen and am very happy with it.
I may be misunderstanding what you are wanting to do though.
 

dkamp

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Aspen500, I do want the HEI system. I looked up the DUI brand on Summit, and it was in the $330 range. Ouch.
I was hoping to assemble all the components needed from a salvage yard like a few other posts on the slantsix and forabodiesonly suggest. They suggested a year range of Chevy's as donor parts. But I'm a little simple and need more specifics since other forum posts also disagree with the year ranges. Hoping to stir the knowledge pot here. I may need to create an account on those sites and resurrect Old posts to ask.
 

Aspen500

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The 8 pin should work as shown in the diagram. Since yours uses the distributor to generate the signal and control the timing and not a PCM, which uses the 4 pin connection. A 4 pin should be easy to find, or get one from the parts store, they aren't overly expensive.

You probably know this but, the module has to be mounted on a heat sink and have dielectric grease between it and the heat sink. Otherwise it won't last very long.

If you can find an HEI with a remote (not in the cap), coil, it will work good. Trying to recall, think mid to late '90's Chevy/GMC trucks have what you need. Also same era and into the 2000's S10.
 

Lightning II

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decided I'd pop in on this one: the parts store part number for the module is DR100 at Autozone. AC Delco still sells the heat sink that they mount to at the parts store. I did the swap and I'd post more on it, but I'm chasing a fuel issue and I don't want to lead anybody wrong if I've missed something. I will post the picture of just the module addition though.

On the wires going to the coil, I’m needing to redo one of them.

158869E7-DD81-456A-90BF-49694C612E1A.jpeg
 

dkamp

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I did this:
Stripped the Mopar box, added the GM.
1674357803386.jpeg

Made a Heatsink from 1/8 Aluminum and used the heatsink compound
1674357954477.jpeg

that primary goal was to keep it as Mopar looking as possible. For the Coil I used an e-core that the Primary was .5 Ohms from a Chevy S10 Blazer. I had to reverse the Distributor Pickup wires to get it to run right.
I may need to tweak the timing. It runs good until you put your foot into it. It has a stutter every 3-5 sec like misfire?? but does accelerate better that with the mopar ECU. I did regap the plugs to be 40.

dkamp
 

Hayzoos

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I sourced parts for a 1976 Chevette. eCore coil, pickup (for connector) and same 4-pin module since it all uses spade connectors it does not jump out as different. I can also say I am running a 'vette ignition.
 

cal30_sniper

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96-00 Vortec trucks provide an excellent coil bracket and module heat sink.
93F5B4C7-9E87-41A3-BC10-CED69CD08C4E.jpeg

The Vortec module is not useful unless you’re running something like MicroSquirt for computer controlled ignition, but the heat sink can easily be modified to take an older 4 pin HEI module. The Vortec coil is also not great for use. It requires a special plug wire boot and clip (same retention clip and boot as LS coil packs), and will also cause an older 4 pin module to run really hot (I believe the Vortec coil dwell is significantly different than the older external coil HEI dwell times.

Pretty much any pre-computer GM product will have a 4 or 5 pin HEI module, that is what you need. 70s and early 80s pickups are great candidates, and it doesn’t have to be a V8. 5 pin modules are functionally the same, but have an extra pin that retards ignition if grounded. These were used in some special applications (early turbo cars and some other oddball stuff).

I prefer the TPI/TBI style external coil. It’s the same as the 4 prong spade connector type you see used in the swaps, but come with unidirectional sealed connectors. This provides some extra insurance against incorrectly hooking up the spade connectors in the event of a repair or replacement. These are commonly found in TBI cars, trucks, and vans from the 80s and early 90s.

New connectors for the 4 pin module and TBI coil are available to make a clean install that is repeatable if something needs to be replaced or disassembled.
 

Lightning II

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What’s everybody doing with the hot wire that’s in the body harness? (In the ‘87 model it’s Pink in color.)
 

dkamp

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If you are referring to the Ping wire for Coil 12V, I added a Relay. The 12V from Alternator goes to the relay and then to the Coil.

The Connections for this is pin 30 of the relay goes to Alternator 12V source. Pin 87 (that is Normally Open) goes to the Pink coil wire. This is switched by Relay pin 86 to Ground, and the OLD Ignition power that was on the OLD Coil 12v that is HOT with Key ON to relay pin 85.
Hope this helps.
dkamp

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Lightning II

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That actually helps quite a bit. I was going to head to the local U-pull-it to look at some relay boxes and such to see what I could make work.
 
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