Genuine Junk Yard Genius.com Ignition Upgrade For:
AMC/Jeep 258 CID (4.2L) I-6 Engine, 1976-77


The biggest problems with the '76 &'77 AMC Jeep Ignition is it was manufactured by Prestolite.
Prestolite manufactured a distributor with a 'Hall Effect' trigger. This means there is a full 12 volts going to the trigger, and no aftermarket module will work with it.

Prestolite also made the distributor with a plastic vacuum advance canister that is guarinteed to fail as the gasoline vapors from the vacuum source (intake manifold) condense in the plastic.
Add to that mix, intense engine bay heat, petrolum 'crud' collection on the outside, and age, and you have a part guarinteed to fail in the shortest possible time.

The Prestolite ignition module was a very weak and poorly designed unit (as most first generation are).
Prestolite built that ignition as a 'Stand Alone', there are no upgrades in later year models, so there are no updated parts we can adapt for use on this particular ignition.
This means no quick change for better parts like there are for GM, Ford & Chrysler Ignitions.

Now, for the bad news... There are NO UPGRADES for the prestolite ignition in AMC I-6 Engines I'm Aware Of...


Now, for the good news...
The AMC I-6 Engine was used with a variety of ignition systems... and with the Prestolite being a 'Stand Alone' system added as an after thought, it's easy to remove.
That means you can change the entire ignition system over rather easily to one of the other ignitions AMC/Jeep used through the years.

The 'Best' upgrade right now is the '78-'79 Jeep I-6 Motorcraft/ DuraSpark Ignition.
Available at junk yards, swap meets, discount parts stores everywhere.
Uses all stock parts from one sorce or another so parts are available everywhere.
Infinitely Reliable, Upgradeable and Tunable, this ignition system is the workhorse that powers millions of Jeeps (all Jeeps,'78 to '90) and millions more Ford vehicles (all Ford, '76 to '91), so replacment parts aren't going away anytime soon! and billions of quick starts daily can't be wrong!

There are other options,...
The '73 & Older Jeeps were equipped with Delco Points type ignitions.
This Delco Distributor can be use with the braker points to trigger a virety of aftermarket modules, Including MSD's 6 Series Modules.

These Delco Braker Points distributors can also be easily upgraded with more modern distributor caps, rotors, electronic triggers, ect.
Sence this is the same type of Delco distributor used in GM vehicles for years, everyone makes something for them.

There are also Aftermarket Manufacturers cranking out replacment distributors, but most rely on some sort of proprietary parts that only the manufacturer sells.
This leaves you stranded until the often very costly replacment parts arrive, if the manufacturer even still makes the parts you need or the manufacturer is still in buisness.
The inital cost of these aftermarket units is VERY HIGH!
Anywhere from $400 to $600 (usd) while a Motorcraft remanufactured replacment distributor from most discount auto parts stores is well under $100 (usd).
(The last one I purchased was $78. including tax.)

I'm posting the orignal wiring diagram for the Prestolite Ignition system.
All I-6 AMC Jeeps used the Delco Alternator in '76 & '77.



As you can see, the Prestolite Ignition was simply 'scabbed in' after 'Splice R', so removing the ignition in it's entirety is relitavly easy, leaving a good sized supply wire to start your upgrade from.
Here is how to properly remove the Prestolite Ignition.

As you can see, the stand alone system is easy to remove.

The biggest problem with the Motorcraft/DuraSpark Ignition upgrade is the wiring harness.
Collecting the correct connectors, correct size and color coded wire, and knowing all the little secrets to keep everything working the way it's supposed to.

Here is the upgrade wiring harness diagram you will need for the Motorcraft/DuraSpark igniton upgrade.


As you can see, there are factory connectors, resistor wires, ect. that will have to be aquired, besides the Distributor & Ignition Module, and I don't have part numbers or sources for all of these.
What I do have is listed in the chart below...

CHART...


Once you have installed the Motorcraft Distributor from a '78 or '79 Jeep with an I-6, You may want to upgrade the cap, rotor, ect. Click Here.

Now that your distributor is in, there are 3 ways to proceed.

  • 1. You can use the stock DuraSpark Ignition Module.
    This will require you to purchase or fabricate an ignition harness.

  • 2. You can use an MSD Module and skip all the harness building. The only thing the MSD module requires is a 'Ford To MSD Connection Harness' and drive the MSD Module directly from the Motorcraft Distributor.

    The MSD 6 Series Ignition Module is recomended for this application.

    Here is the wiring diagram recomended when you use the Motorcraft distributor and MSD 6 series module.


    I choose my aftermarket suppliers VERY CAREFULLY! They have to have been in buisness quite a while, be respected by the automotive community, and make nothing but top quality parts or I won't recomend them.
    I won't hesitate a second recomending MSD as an aftermarket supplier, and I don't say that about anyone but Holley and MSD.

    Using the Delco Points Type Distributor To Upgrade.
    To upgrade to the Delco Points Type Distributor, things are pretty easy, but you will have to rely on MSD as an aftermarket supplier.

    This is a diagram for the standard Delco breaker points ignition.



    Remember, if you are going to use points, you will need an ignition resistor or internally resisted ignition coil, and/or the proper ignition coil for points.
    Depending on the type of starter solnoid you have, you may have to change it also.

    This is how I upgrade the Delco braker points distributor cap, rotor & plug wires.

    This is how I update Breaker Point Distributors To Electronic Triggers.
    Once this conversion is done, you can trigger any of the factory stock or aftermarket ignition modules with the exception of the Prestolite module.


    How To Install A Distributor & Verify Timing.