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75 CJ6 Not Really A "Build"

Discussion in 'Builds and Fabricators Forum' started by fesser, Dec 12, 2015.

  1. Nov 5, 2020
    neohic

    neohic Gentleman Jeepist

    Woodland Park, CO
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    500
    Had another read through the whole thread. Brilliant! Such a great CJ6 project.
     
  2. Nov 6, 2020
    fesser

    fesser Napa, CA 2024 Sponsor 2022 Sponsor

    Napa, CA
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    Thanks Neohic. I will probably need to read through it again to remind me what I was doing. Mike and Kyle, I doubt I will be selling it. I was speaking out of frustration caused by my lack of progress on about a half dozen projects. I will keep you guys at the top of my list if I do decide to do something crazy.
     
  3. Nov 6, 2020
    '74Renegade

    '74Renegade Active Member

    Fair Oaks, CA
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    I know the feeling, I've toyed with selling now and again, but always know that I'd want it back later. Glad to hear you're thinking about the jeep again.
     
  4. Oct 28, 2021
    fesser

    fesser Napa, CA 2024 Sponsor 2022 Sponsor

    Napa, CA
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    Well, it has been another year of neglect for the CJ6. Had to clean out the shop for a retirement party. After the party mess was cleaned up it dawned on me that there was enough room to bring the CJ6 back inside. Not sure how quickly I can get back to work on her though. I have a list of things that need to get done first but moving it (and getting the rat sh-t out of it) is a start.
    Fresh out of the tent carport and home for wayward rats...
    [​IMG]
    [​IMG]

    Getting stripped of parts that were last put on for mock up purposes...
    [​IMG]

    Gave it a quick bath/disinfecting. Then gave myself a lesson about failing to see if it is still in neutral before dragging it forward with the old Kubota...
    [​IMG]

    Safe and sound in the shop...
    [​IMG]
    [​IMG]

    I built a good fire and put every fan I could find on it. Too late to stop the rust, but I want it dry so I can look it over tomorrow. I think I will start with trying to wire it up so I can get it started. I might be a lot more motivated if it will move under its own power.

    Question for any body/paint guys. Does all the body need to come off since it has been exposed to humidity and other elements for over a year?
     
  5. Nov 1, 2021
    fesser

    fesser Napa, CA 2024 Sponsor 2022 Sponsor

    Napa, CA
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    After dragging all of the boxes of parts I could find back into the shop I bolted the radiator in for a test fit. The stock shroud isn't going to work but I am not surprised. The engine sits a little lower and off center than the 304 did. I still need to figure out hoses since the stock Chevy ones won't work. Installing the radiator only required a slight hogging out of holes on the rad support to get better alignment.

    [​IMG]

    The biggest hurdle (that I keep ignoring) is the wiring issue. I have the stock 91 Chevy tbi harness still on the engine, and the stock Cj6 harness sitting on a bench. I am not liking the overall condition of the CJ harness. There are a lot of cracked wires, cut wires, and wires that some prior owner spliced in in the past. I have been told that combining the TBI harness and the CJ harness isn't all that hard, but, to be honest, the more I read the more I feel like walking away from it and towing it to a shop. One problem I have is trying to figure out what the engine doesn't really need. What I mean is, most sites I find want to eliminate almost everything on the engine for performance reasons or to eliminate smog. I personally don't mind leaving harmless smog related items on the engine if it doesn't hurt anything. This engine, smogged out, will be more than enough power for my needs. I am worried that I will eliminate something that will end up confusing the computer down the road.

    I found a place (I think) to mount the computer from the Chevy. The heater takes up most of the room under the dash on the passenger side. I have it temporarily hanging from the cowl air intake duct. As near as I can tell, this spot may work if I can aim the speedometer cable away from it. I am waiting on a 90 degree cable adaptor to see if I have enough clearance.

    [​IMG]

    [​IMG]

    While searching just now I found where I asked the same wiring questions on this forum in April of 2019 including lots of useful replies. Going to start with what TIMGR suggested back then...

    "GM charging system should be just a 10SI or 12SI alternator. Look at the wiring diagram for the 1975 or 1976 CJ and copy that. The sixes had a 10SI from the factory, so the scheme for them is mixed in to the same diagram for the V8s. Look at the diagram with this in mind and it should be clear.

    There are lots of systems that depend on the ignition system. You will need a connection to ignition power to turn the ECU and fuel pump on. You need the original distributor since its advance is controlled by the ECU. I don't know where the TBI/MPI Chevys take ignition power from. If it's from the ECU, then you will not need any connection to the ignition, since you've covered that by sending power to the ECU. If it's separate, than you will need to arrange a power lead to the ignition, likely from your new relay-driven panel that turns on the ECU and fuel pump (see next paragraph).

    You will be eliminating everything that goes along with the Prestolite ignition. The Prestolite stuff has a power lead to the module and a coil lead. Both of these plus power for the regulator come from splice "G" hidden inside the loom under the hood. This is shown clearly in the TSM wiring diagram. I would take those wires back to that splice and use that lead to my new EFI power panel. That may not be enough power to run the fuel pump; typically a separate wire is run from the solenoid that powers the panel and the original switched power is used to turn the panel's relay on and off. The Prestolite ECU needs nothing from the starting circuit, so leave that unchanged.

    You will need to figure out where to put the GM ECU and how to run the wires. As I recall, there are a lot of extra wires in the GM harness that you can prune out. I know nothing specific about this, but there are articles on-line that discuss it. I expect you will at least need the harness diagram from the donor, maybe the pinout and description of the ECU to complete this part.

    This should give you a place to start. (y)"
     
    Last edited: Nov 1, 2021
    txtoller and ITLKSEZ like this.
  6. Nov 1, 2021
    ITLKSEZ

    ITLKSEZ Hope for the best, prepare for the worst

    Liberty Lake, WA
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    When I was heading into the wiring on mine, the thought of it was making me feel physically ill. There were whole hours where I’d sit and stare at it, unsure where to start and questioning my reasoning for starting down this road. It really helps to not look at the whole picture. Focus on one wire at a time, and walk away when you’ve had enough or get stumped. Chances are, when you come back to it after a short brake, it’ll make sense again. Good luck!
     
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  7. Nov 1, 2021
    fesser

    fesser Napa, CA 2024 Sponsor 2022 Sponsor

    Napa, CA
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    You described exactly how I feel, which is actually kind of scary because I consider you one of those people who can do everything. I am following the advice of you, Timgr and others though and am going to approach it one wire at a time. I bookmarked my old posts, all the efi sites and articles that seem to be understandable to a novice, and made a big clean work area to lay out the harness(es) on. I even dragged the laptop out to the shop. I am going to start with the Jeep under hood harness first as I don't think much, if anything, is going to change under the dash. I dug up my 75 and 76 manuals for the wiring diagrams and I guess I am ready to start chasing and labeling wires.

    [​IMG]
     
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  8. Nov 1, 2021
    Norcal69

    Norcal69 Out of the box thinker 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Northern California
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    The chevy TBI is just going to be a matter of removing the unnecessary pins and installing some pins in the basic necessity spots. The really simple ecm's just need power in from the battery, engine cranking signal power and engine run power. You will just need to find those wires in the old jeep harness and allocate them to the TBI harness. How complete is your TBI harness, do you have the fuel pump relays and all? If not you may want to talk to Affordable Fuel Injection and get a stand alone TBI harness setup.
    If I lived 2 hours closer I would help you knock this out!
    Whats your ECM number? I may have the ECM pin out locations and descriptions that you need.
     
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  9. Nov 1, 2021
    fesser

    fesser Napa, CA 2024 Sponsor 2022 Sponsor

    Napa, CA
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    Thanks for the positive thoughts. I have been staring at the wiring diagrams, and the harnesses and I am sure I am overthinking a lot of this stuff. For instance, On the CJ wiring diagram, they show wiring for the oil pressure gauge and sending units. My Jeep had been swapped to a mechanical oil pressure gauge at some point. No problem, until I started wondering if the Chevy computer is going to care that there is no gauge...probably not...but is it going to care if I eliminate the Chevy oil pressure sending unit so that I can run a mechanical one...maybe. And that's when I start thinking too much.

    To answer your questions, my TBI harness is pretty complete.
    [​IMG]

    [​IMG]

    [​IMG]

    The ECM number is 1227747.

    I think one of the things I need to find is a diagram that shows what the terminals on the Chevy bulkhead fitting (the square one that goes through the firewall) are. There are a lot of plugs that are hanging off the engine harness that have nothing to plug into. I would feel better knowing what they were before pulling them.
     
  10. Nov 1, 2021
    Norcal69

    Norcal69 Out of the box thinker 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    You have the same ecm that Howell uses. I’ll get the diagrams posted tomorrow.
     
  11. Nov 2, 2021
    fesser

    fesser Napa, CA 2024 Sponsor 2022 Sponsor

    Napa, CA
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    Thanks!
     
  12. Nov 2, 2021
    Norcal69

    Norcal69 Out of the box thinker 2024 Sponsor 2023 Sponsor 2022 Sponsor

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  13. Nov 2, 2021
    duffer

    duffer Rodent Power

    Bozeman, MT
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    Radiator hoses:
    I used these on my 3B. Upper Radiator Hose: Gates 20603, Lower Radiator Hose: Gates 20609. I had to trim a couple inches off the radiator end of the upper so it may be just about perfect for your project.
     
  14. Nov 2, 2021
    fesser

    fesser Napa, CA 2024 Sponsor 2022 Sponsor

    Napa, CA
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    Thank you Norcal69 and Duffer! Still messing with tracing back wires. Norcal's top image is a great help already (I am a "visual learner"). As soon as I get fed up with playing with wires I will look up the hose numbers. Much appreciated.
     
  15. Nov 10, 2021
    fesser

    fesser Napa, CA 2024 Sponsor 2022 Sponsor

    Napa, CA
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    Wiring is coming along, slowly. I am getting close to the point where I will be asking for people to confirm if wire x goes to terminal y.

    In the meantime I set my son-in-laws Christmas present in the back of CJ6 to get it out of the way and to see if it settled the rear springs any. Not sure what a 225 Buick weighs off-hand, but it did settle the Jeep a little as I lowered the engine onto it. Some of you may recall that I don't like my rear shackle angle very much. Here is what it looks like with the engine in the back.
    [​IMG]

    [​IMG]

    The thing that bothers me about the rear shackle is knowing that it isn't anything I did wrong. The kit indexes off of stock mounting points. I am thinking of moving the forward spring hangers back an inch or so. Any thoughts?
     
  16. Nov 10, 2021
    Norcal69

    Norcal69 Out of the box thinker 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Northern California
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    You might want to think about moving the rear hanger forward.
    Moving the front hanger backwards will move the tire backwards and increase the chance of tire contacting the quarter panel when the suspension flexes.
     
  17. Nov 10, 2021
    fesser

    fesser Napa, CA 2024 Sponsor 2022 Sponsor

    Napa, CA
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    That would be easier to do too. Do you think the front looks like it has enough clearance? I know it moves backward under compression, I am just not sure how much. If it went straight up now it would hit.
     
  18. Mar 7, 2023
    CraigE

    CraigE Member

    Greeneville, TN
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    Any updates on this project? I enjoyed reading through the entire thread. (y)
     
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  19. Mar 7, 2023
    vtxtasy

    vtxtasy oldbee 2024 Sponsor 2023 Sponsor

    Tucson, AZ
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    X2..."Not Really A Build"
     
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