OK, you asked for it, so here it is….
(WHY do I want to do this ANYWAY??? ** See end of article)
STEP BY STEP to convert your Mopar ignition
over to a GM High Energy Ignition system.
(The example here is for a small-block V-8 engine, but with exceptions for mounting the module, because of distributor location, this will work exactly the same for a big-block or a slant-six engine)
PARTS YOU WILL NEED:
A quality mid-late 70’s GM HEI Module (Standard Ignition # LX-301 – AC Delco # D1906 – Borg Warner CBE4)
A factory plug that will connect to the Mopar distributor pickup plug (Junkyard).
Some sort of heatsink for the module. There are different ways to do this, as wide as your imagination.
I used a flat piece of aluminum. The heatsink MUST be grounded, because the module MUST be grounded.
A couple of small machine screws to attach the module to the heatsink.
Heatsink grease or die-electric grease (This will usually come with the purchase of the module)
Four ¼” female spade connectors, four ¼” male spade connectors and a couple of eyelet connectors for the coil connections.
Several feet of 14-16 gauge wire (Different colors so you don’t confuse which wires are which)
An aftermarket coil. One that does NOT have a ‘built in’ ballast resistor (70’s era Fords for example) and can handle FULLvoltage. There are many options out there, I chose to use an Accel ‘Super Stock’ coil (# 8140M) A Mallory # 29216 or a Standard Ignition # UC12X are good choices also.
Miscellaneous hand tools. These depend on how ‘bullet-proof’ you want to make this, but a normal set of tools is all you need.
PARTS YOU MAY NEED:
The factory GM plug that fits on the ‘pick-up’ side of the module.
Solder, soldering iron, shrink tube, split loom.
You probably want a GOOD cap and rotor. A heavy-weight one with brass/copper insets. Not the feather-weight junk with aluminum inserts (Good ones are Accel # 8320 – Standard Ignition # KCR100X – Borg Warner # C156 and # D147)
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OK, WHERE DO I START?
First thing you do, is decide where you want to mount your module. This will be dictated by what kind/size heatsink you’ve decided to use, and how easy you want to make it to get to. They can be mounted almost anywhere in the engine compartment. As usual, the shorter you can make the wire runs, the better.
I decided to mount mine on the firewall, next to the voltage regulator. This made it easy to get to, short wire runs, and provided a good ground. (Again, having a good ground is very important!) I also remounted the coil, because The Dodge Boys decided to mount it to the rear of the intake manifold, but it’s not very easy to get at. I made it easy.
Now that you’ve decided where you’re going to mount the module/heatsink, you need to drill the mounting holes in the heatsink (To mount it to the body) and drill the mounting holes for the module.
IMPORTANT!
There are one or two little plastic ‘nubs’ on the back of the module. This is so it would ‘seat’ into a GM distributor. You must CUT THESE OFF (Box-knife, Xacto knife) or the module will not set flat to your heatsink.
Position your module, mark your mounting holes, and drill the holes. I tapped 10-24 threads into my heatsink, but if you have room behind the heatsink you can use screws/nuts. I suppose you could use sheet metal screws also, but I trust machine screws a lot more.
Slather up some heatsink grease or dielectric grease on the back of the module and firmly bolt it to your heatsink. MAKE SURE it fits flat! You should see some grease squish out the edges. Now, mount your heatsink.
Sorry about the fuzzy picture…
Now you can measure/cut/make your wiring.
(NOTE: Yes, you can just crimp the terminals on the ends of the wires. This is Cheesy-Mickey-Mouse though. What you want to do is SOLDER the terminals on and then shrink-tube them. You are trying to make this as bullet-proof as possible. Crimped terminals are WEAK. You especially want to shrink-tube the female spade connectors that connect to the module. Just to make sure nothing comes into contact with them. This will insure your electrical connections are bullet-proof..)
Here is the schematic… Very simple. (KISS!)
PICK-UP SIDE
OK, you’ve noticed that the module has three ¼” male spade connectors and one slightly smaller one. You can do this one of two ways. If you got the factory GM plug for that side of the module, all you need to do is splice/connect/solder the Mopar plug to that. However, if you do what I did, you can use two ¼” female spade connectors, even though the one will be slightly too big. All you need to do is, squish the connector a little flatter. (Needle-nose pliers work well) It will be a nice tight fit then, and I’ve never had a problem with mine yet.
(IMPORTANT: The BLACK WIRE coming from the distributor needs to be connected to the ‘small’ connection on the module. The other colors on the schematic I made are NOT necessarily correct, they are just ‘common’… Your colors and mileage may vary…)
COIL SIDE
This is the easy one. Pay attention to which connector on the module goes to which connection on the coil. It’s basically making up a loom with two ¼” female spade connectors on one end and eyelet connectors on the other. Make sure you leave the factory connection on the plus (+) side of the coil.
(BTW … The extra wire you see on the negative (-) side of the coil on the picture of my setup, is my tachometer connection. The capacitor/condenser on the module, is the radio noise suppressor that I relocated, when I relocated my coil.)
OK, you’ve got your module mounted, and have your wires made up. Unplug the factory connector at the distributor and plug in your new connector to the distributor. Plug your wires onto the ‘pick-up’ side of the module. If you haven’t changed your coil yet, now is a good time. The only factory lead you will want to keep is the power lead (Coming from the ballast resistor) going to the + side of the coil. Attach your other wire loom to the coil and tighten the nuts up. Connect the other end of your wire to the other end of your module. Double check yourself to make sure you have the right wire going to the right connector on the module. Disconnect the factory 4-5 pin connector going the factory ECU. (Any factory connectors, you might want to protect them with some electric tape, just in case you ever decide to reinstall the factory ignition)
You should now be able to start and run your engine! But wait, we’re not done yet! A big reason we did this was to getRID of the ballast resistor. You need to make up two wires about 5” long with ¼” male spade connectors on them. Unplug the connectors on the ballast resistor and plug in your new wires as shown.
You’ve now eliminated a weak link in the Mopar ignition system and have a system that runs off of full voltage.
OK, you’re done! Now you may want to do a ‘prettier’ job than I did, it’s up to you and your imagination. Mine is not a show truck, I just tried to make things as bullet proof as possible.