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  1. #1

    Default 84 LTD LX CFI/AOD to SEFI/T5

    Looking to convert my LTD LX to SEFI and a T5 this summer, and I've heard/read around the web that a harness from an 86 mustang will be almost plug and play. My questions are:
    1. Is this true? (I have an 86 GT factory T5 parts car that I bought when I owned my mustang)
    2. Is this swap difficult?

    P.S. I also have the EVTMs for both cars and Haynes manuals for both. Any help is greatly appreciated!! Also first post and glad to be apart of this community! Four eyed ftw!


    Sent from my iPhone using Tapatalk
    1984 LTD LX, 160k mile Explorer 5.0, Comp XE264HR-14 cam, Alex’s Parts springs on stock GT40 3 bar heads, Unported Explorer intake, 1 5/8 shorty headers, off-road H-Pipe, Spintech 9000 mufflers, Holley Terminator X Max, J-Mod 4R70W, Mustang 8.8 w/ 3.73s, Tubular front and rear control arms, front coilovers, Turbocoupe rear coil springs

  2. #2

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    welcome.

    I've owned quite a few 86-88 sefi cars. There is a vast difference between some of the connectors on some cars depending on options, then there are some cars that are exactly the same.

    My $.02, The engine is almost completely isolated wiring wise from the body except for a few fuseable links that feed the ecm/fuel pump and wires through the ignition switch. If you are comfortable with wiring and proficient at reading wiring diagrams, it really shouldn't be all that bad.

    This forum is a great resource and people are very willing to help, especially with specific questions when described accurately.

    Wish you the best and let us know the plan, maybe post a few pictures.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  3. #3

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    In 1990 I converted a '78 fairmont v8 wagon using a complete wrecked 1986 mustang gt with a 5 speed and called it the Musmont. I took out all the '78 wiring harness, dashboard, suspension ,heater ac unit and installed all the '86 parts. I remember having an "ah ha moment" when I first took the dash cover panel from my wifes' '86 gt daily driver and super imposed it on the '78 dashboard.

    I did have to modify the firewall a bit for the ac, but not difficult.

    There is a 5" difference in wheel base so the the wiring to the rear of the car and fuel lines and exhaust will have to add 5" of length. In addition, I left the '78 roof courtesy lights wiring in and spliced them into the '86 wiring.

    All the suspension bolts in, including the k member, you can even install the rear quad shocks.

    The driveshaft can be reused or a newer one can be made using the '86 yoke ends. The ears of the trans cross member needs to be modified to fit the '78 brackets.

    The '86 fuel tank can be made to fit if you modify the spare tire well, or you can use your ltd tank and reinstall the pump and sender units. There may be some information posted by others about that on this website.

    The k member and engine /trans can be removed as a single unit from below by lifting up the front of the donor car and dropping out the assembly and reinstalling the assembly into the project car. I also reinstalled all the old parts back into the donor car for storage/scrap purposes to use a roller.

    Good luck with the swap, it is worth the effort in the end. I have done three of these swaps so far and actually have a fourth one in progress that is for sale. Look for my ad in the for sale section here for pictures of before and after using a '90 donor car.
    more foxes than cents

  4. #4

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    Since you have a parts car it should be a fairly easy and painless conversion.

    The trickiest part will be getting the shifter through the console. This is one area where the previous owner of my car really messed up when converting to 5-speed. He hacked up [destroyed] the console to fit the Mustang hump and boot.

  5. #5

    Default

    Quote Originally Posted by frinkspa View Post
    In 1990 I converted a '78 fairmont v8 wagon using a complete wrecked 1986 mustang gt with a 5 speed and called it the Musmont. I took out all the '78 wiring harness, dashboard, suspension ,heater ac unit and installed all the '86 parts. I remember having an "ah ha moment" when I first took the dash cover panel from my wifes' '86 gt daily driver and super imposed it on the '78 dashboard.

    I did have to modify the firewall a bit for the ac, but not difficult.

    There is a 5" difference in wheel base so the the wiring to the rear of the car and fuel lines and exhaust will have to add 5" of length. In addition, I left the '78 roof courtesy lights wiring in and spliced them into the '86 wiring.

    All the suspension bolts in, including the k member, you can even install the rear quad shocks.

    The driveshaft can be reused or a newer one can be made using the '86 yoke ends. The ears of the trans cross member needs to be modified to fit the '78 brackets.

    The '86 fuel tank can be made to fit if you modify the spare tire well, or you can use your ltd tank and reinstall the pump and sender units. There may be some information posted by others about that on this website.

    The k member and engine /trans can be removed as a single unit from below by lifting up the front of the donor car and dropping out the assembly and reinstalling the assembly into the project car. I also reinstalled all the old parts back into the donor car for storage/scrap purposes to use a roller.

    Good luck with the swap, it is worth the effort in the end. I have done three of these swaps so far and actually have a fourth one in progress that is for sale. Look for my ad in the for sale section here for pictures of before and after using a '90 donor car.
    I've done pretty much the same thing except I kept the late Fox ('90) dash. So, I honestly don't know what you'll have to do to make it play nice with an LTD dash.

    The thing about the crossmember he mentions won't be necessary on yours. The crossmember brackets changed around '82, so you won't have to modify a regular Mustang double-hump crossmember at all.

    If I were you, I'd keep the LTD tank and sender, and modify it to fit a high pressure SEFI fuel pump. This is what I did on mine. You should't have to do anything with your CFI fuel lines, they should work as is (I think). Unless there's an external pump too, in which case you'd have to make something to bypass it.

    The only other thing I'd add to what frinkspa says is, you can use Mustang exhaust. I have '90 LX 5.0 h-pipe and catbacks on my car, only I did have to lengthen my catbacks between the forward flange and mufflers, and then again between the axle and the end of the tailpipes. Fits like it belongs there!
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  6. #6

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    Just found this one. I hope you haven’t given up. You certainly have many of the tools and parts you would need. I used an aftermarket conversion harness and the evtm for the 1985 ford ltd wagon. This past week I have driven it twice to work and I cruise it in the evening after work quite a bit. I believe the rumors are true about 86 harness making it easier for you. Since you have the evtms you should be able to trace out the connector you need. Look for the connector that powers the computer. Not sure if the 84 has an eec-iv computer but that’s an important one. The aftermarket ford harness requires the location of 7 wires I believe. In answer to your second question, yes, it can be difficult. It all depends on you. Do you like working on cars? Experienced with engine replacement? Willing to spend a lot of money on a car project? I personally have spent thousands on my car and I completely ignored cosmetics. All of my labor was performed by me in my driveway. I used 2 different donor mustangs, 1 for powertrain and 1 for suspension and brakes. Can you imagine going to one of those tv mechanics and having them build one of these. I’m sure they can and would do it at a cost probably equivalent to a new mustang if not more. Currently I am throwing gaskets at a lightning 351w to put into mine, even though I am having a blast with the 302. Good luck and keep us updated. Happy Thanksgiving and welcome to FEP!

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