258 harness question

[Tony Marc]

Well.... After searching... I'm still not 100% sure. I have a 258 from a 86 CJ. I'm looking to take out all the computer stuff as well as go with a MC2100 set up as well as the TFI ignition upgrade. The 258 came without the engine harness so I have nothing to "nutter". So I'm trying to figure out my best and most cost effective options... Do I :
1. Get a used 258 harness and do a "nutter bypass" on it ? Of course it will need to be from a Jeep that was ECM equipped.

2. Get a used harness from an early 258 that didn't use any computer carb stuff? I'm guessing a 81 or so harness would work. And do I need both the engine harness as well as the dash portion?

3. Bite the bullet and get a brand new harness (this is really beyond my budget at this point).

Keep in mind ... I do have the dash part of the 85 harness for the fuse box,gauges, and the computer hook up. I'm not looking to keep it period correct or about emission laws. It's going to be registered with historic plates... And visual inspection shouldn't be a problem in NJ.

Any help or suggestions would be appreciated.. I'm kind of at a crossroad with this build.... Well... This is the 2nd crossroad. The 1st one was when I ditched the idea of a FI 5.0L...I seem to always have a negative cash flow position. Thanks for any help

 

[PoliceMonkey161]

Tony,

If I understand what you're after, then you won't need the ECM harness portion of the engine harness. They are seperate, so if you had all the OEM stuff from the get go and wanted to do the upgrades you mentioned, you would just remove the ECM, it's harness, solinoids, etc. If your installing an upgraded distributor and carb, you wont need that part of the harness. You'd be essentially installing it to bypass it.

If you still have the bulkhead at the firewall (the black plastic box that the front engine harness plugs into, you can track down a used engine harness. There will be some minor mods like removing the spark control module plugs/connectors and running a new power source for the TFI, all of which is do-able. If your existing dash harness is usable, re-use it if your on a budget, it really did not change from year to year (some minor changes, but nothing that can't be worked out).

If you have the money, Painless and Centech both make OEM style replacement harnesses or there are several companies that make a "universal" harness if your so inclined mechanically.

Once you remove the emissions stuff from the Jeep, the basic 258 was the same regardless of the year it was manufactured (beware, some of the internals like oil pumps and headbolt size were slightly different from various years).

 

[Tony Marc]

Tony, If I understand what you're after, then you won't need the ECM harness portion of the engine harness. They are seperate, so if you had all the OEM stuff from the get go and wanted to do the upgrades you mentioned, you would just remove the ECM, it's harness, solinoids, etc. If your installing an upgraded distributor and carb, you wont need that part of the harness. You'd be essentially installing it to bypass it. If you still have the bulkhead at the firewall (the black plastic box that the front engine harness plugs into, you can track down a used engine harness. There will be some minor mods like removing the spark control module plugs/connectors and running a new power source for the TFI, all of which is do-able. If your existing dash harness is usable, re-use it if your on a budget, it really did not change from year to year (some minor changes, but nothing that can't be worked out). If you have the money, Painless and Centech both make OEM style replacement harnesses or there are several companies that make a "universal" harness if your so inclined mechanically. Once you remove the emissions stuff from the Jeep, the basic 258 was the same regardless of the year it was manufactured (beware, some of the internals like oil pumps and headbolt size were slightly different from various years).

Hey PoliceMonkey161, thanks for the response. So if I understand correctly...an older non-ECM harness should work? You hit the nail on the head... I have zero engine harness at this point (no bulk head connection to firewall). I do have the bulkhead connection from the dash to the firewall and intend on reusing that.

I'd love to get a brandy new harness.... But it's just way out of my price range at this time. So I guess my new job will be trolling c/l or eBay for a harness that's not too hacked up. The prices I saw are a bit up there.

Thanks again .... Appreciate the assistance.

Sent from my iPhone using Jeepz

 

[superj]

An ez-wire harness is 180 bucks and is very nice. I just put one in a cj5 we are putting together.

 

[PoliceMonkey161]

It does not have to an older "non-emissions" era harness. The ECM part of the front (engine) harness is separate from the engine harness. Any engine ( and if you have nothing other than the dash, you need the front and rear light harness sections as well) harness from 76-86 for a CJ7 258 will drop in. You could even use a 76-83 CJ5 258 engine harness but the rear section from a CJ5 will be to short. I mention this because it will broaden your search.

 

[carnuck]

You can run a GM HEI dist with AMC drive gear with a carb of your choosing. The harness will be needed for lights etc, but the motor will run that way.