77 cj5 prestolite to motorcraft conversion

[rufus1138]

ok, wanted to start a new thread on this since all the old threads on this subject include tons of fighting about the cam gear on the dizzy I DONT WANT TO TALK ABOUT THAT PART OF THIS MOD IN THIS THREAD, ok moving on the project is as such, autozone as a supplier since i want all new parts

new 1978 cardone reman distributor for amc258 i6 44.99 (website)
new 1978 AMC 258 i6 / 4.2l i6 ICM 34.99 (website)
new 1978 ford i6 cap and rotor 19.99 + 6.99 (website)

my coil is fine for now and the wires/plugs will suffice initially.

the big question, what wiring harness mods to i need to accomplish to make the 1978 system work with my current harness. im going to slowly collect all the parts and have it ready to swap in as a weekend project and later on i will add a dui kit to the system that will replace the coil and wires.

remember no arguing about the cam gear, we are talking about the icm interface from the motorcraft system to a prestolite equipped harness.

 

[IOPort51]

As I recall, it will just plug and play.

 

[rufus1138]

k so the icm for the motorcraft has two plugs coming out of it, that should be one to go to the dizzy and one that will mate up to the harness no problems?

 

[rufus1138]

k, reason i ask is that the junkyard genius website says there is some splicing that has to happen, ur saying that my prestolite icm will pop out and the new one will plug one connector to the new dizzy and one to the harness? just wanna clear up what im getting from the jyg since hes the only one that has addressed the specifics of the swap from presto-motorcraft.

gah, sorry about two posts. i didnt see that the first one had taken properly.

 

[Torxhead]

If you have plans for adding the GM style module, I would suggest doing it now as the wiring would be easier. I did not realize that AMC made an icm, The later CJs came with a Motorcraft version. Good luck with wiring up that new ignition, it is a great upgrade.

 

[rufus1138]

the new icm is a motorcraft unit that autozone sells as oem replacement for the 78 CJ5 with the AMC 258 i6 / 4.2l , i didnt know there was a gm option, i like the ford parts beter but i just hadnt heard about the gm side of this yet.

 

[Torxhead]

I thought you would have seen this:Junk Yard Genius.com 'Stealth HEI Page. Although you will still have to do the wiring conversion from the Prestolite to the Motorcraft.

 

[rufus1138]

nope hadnt seen that, im more interested in having a motorcraft female plug on the wiring harness side of the system, most of these wiring diagrams arent really clear on how that connection works unless its a gm style single wire that only needs switched 12v power.

 

[Jimbos76cj]

The splicing is to go from the comp controlled system to no comp control. If you look up the nutter bypass you can find the proper way to wire it. The ICM plug should be kinda round with 4 female connectors on the inside. The dizzy side will have 3. I'm at work right now so don't have acess to my diagrams but can get some pics tomorrow. I may have a set of stock wires at home I'd send you if you pay the shipping if you don't have yours.

 

[Jimbos76cj]

The "Nutter" Bypass

The second picture down shows the right way to wire it.

 

[Jimbos76cj]

Wait.. Now I'm confused! Your jeep is a 77 so it should not need the 78 distributor and the nutter bypass does no pertain to your jeep.

 

[Jimbos76cj]

So I'm an idiot.. Double checked my facts yes you need the 78 distributor which you already know. For the wiring you will need the different plugs from the 78 and up. Like I said in my dumb post 3 posts ago I may have a set of stock plugs I can send you.

 

[rufus1138]

lol ur talking about the stock plug assembly that would be on the engine harness side of a 78 motorcraft type system right? ill have to look and see for sure how mine is set up, should be factory prestolite, id love it if i could get the plugs from you, we can work out payment thats fine.

 

[IOPort51]

The 78 motorcraft distributor is 2 wire and I think it has the same plug on it as the presto lite distributor has. The ICM is different from the 77 but will still plug in to the distributor and the ignition wires. I think,

And you have no need for a nutter bypass.

 

[rufus1138]

sorry to seem flaky here but i went and dug around under the hood last night after work and it seems for the moment that i may have a motorcraft system already, while i was researching yesterday i definitely didnt remember the big shiny vacuum can on the dissy that the motorcraft has but sure enough it was staring right at me when i popped the hood. so the jury is out at the moment, not gonna worry about it right this second and when i get the tag sorted out ill take the cj up to autozone and see if i can talk them into letting me compare what ive got to known parts on the shelf to be sure. after that we will see where it goes from there. ill pm you io if i need that plug

 

[Hedgehog]

Youi more than likely have a Motorcraft Dist. My 82 motor had a motocraft dist., motorcraft carb. and starter ...... many Ford type parts were found stock on Jeeps.

 

[rufus1138]

77 was the last year of the prestolite system, it may have been changed over, more research will confirm or deny.

 

[Torxhead]

So, if you have the Motorcraft, with the the metal vacumn advance, the Ford cap, adapter, and rotor should fit right on. You did not mention having the adapter though, or the correct spark plug wires.

 

[IOPort51]

you need to take some pictures for us.

 

[rufus1138]

yes the adapter should fit, i have to confirm that the internals are working properly and get the dizzy timing set properly, the plug wires are appropriate, however they are aged quite a bit as is the cap, which im pretty sure is not the ford type. like i said more research is needed, unfortunately it will have to wait till we get the tag title and registration worked out.

lol io thats another project all its own, ive gotta figure out how to post pics from my phone. i tried a while ago and couldnt get it to work, ill make another attempt soon.