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Topic: 83 v8 thunderbird efi swap (Read 431 times) previous topic - next topic

83 v8 thunderbird efi swap

 I just bought a 1983 v8 thunderbird to do a 5 speed conversion on. Also I thought it would be some what simple to do the 5.0 foxbody injection conversion on since its already EFI.
 I did read the sticky conversion.. But it was for 86 and up. Any pointers from anyone that has done this?

Re: 83 v8 thunderbird efi swap

Reply #1
Being an 83 it has CFI with an EEC-III. To go 86-93 Fox Mustang SEFI you're going to have to swap to an SEFI EEC-IV harness. Best bet for that is an 86-88 Thunderbird or Cougar with a 5.0. Or go with an aftermarket stand alone engine harness for an 86-93 Mustang. You're also going to need fuel lines from an 86-88 5.0 Thunderbird or Cougar.
88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, bunch of other stuff.

Re: 83 v8 thunderbird efi swap

Reply #2
So what your saying is find an 86-93 v8 bird or cougar and get the wiring harness? Will it just plug up to the my 83 chassis??
 I was thinking just get a fox body engine,o2  and trans harness , get rid of the 83's engine harness and wire in the fox body harness..

Re: 83 v8 thunderbird efi swap

Reply #3
Unlikely that it, or anything, will just "plug in".

My car ('83) was originally a 5.0/auto. I manual swapped it and kept the EECIII for a while. Later I 2.3T/T5 swapped it, using stock EFI stuff. I used a harness from an 85 or 86 TBird, I think. I don't remember. It was almost 20 years ago when I did it. It however, did not just plug and play. It's got a MegaSquirt in it now, which has been in the car for a while now.

There isn't going to be much on the "chassis" side that you're going to need. You need to sort out a couple main power wires, but most of the main stuff will be there, seeing as the car was already EFI with electric fuel pumps. You're just going to have to grab wiring diagrams and compare to see what's what.
Long live the 4-eyes!  - '83 Tbird Turbo

Re: 83 v8 thunderbird efi swap

Reply #4
10-4.. I appreciate the help. Think I could just wire in the foxbody harness...I have all the info on wiring that I am building a 2000 v8 5 speed ranger as well.
 I just ran across the is 83 with 90k original miles one owner that I couldn't pass up

Re: 83 v8 thunderbird efi swap

Reply #5
So I would highly suggest going aftermarket like Painless like one of these two:

or Ron Francis like this one:

The reason I say this is I stripped the EEC completely out of my '83 to put the carbed 351W in it and everything works as it should.  You can take this same approach and then put an aftermarket harness in the car which will avoid stuffing at best a 27 year old harness EEC-IV from a Mustang or at best a 32 year old EEC-IV harness from a T-Bird or Cougar in it.  With the EEC-IV cars the engine harness integrates into the dash harness so everything plays better with factory harnesses.  You are not in that category so why put an old harness in the car and risk electrical issues which make a project like this a bummer.

However, if you are a wiring guru then play on with the factory harness.

As for the fuel lines there are two ways you can do this that I know of.  One is to modify the stock sending unit / fuel pump hanger assembly to accept a high pressure fuel pump like a Walbro 225 lph unit.  The pump that is currently on it is a low pressure unit that moves fuel to the high pressure pump mounted on the passenger rear subframe.  Then you will need to either find factory 5.0 fuel lines for the high pressure and return lines to the motor.  Another option would be to remove the low pressure fuel pump from the stock sending unit / fuel pump hanger assembly and weld up the holes from the fuel lines that pass through the stock sending unit / fuel pump hanger assembly and reinstall into the tank.  From here you will need to build a high pressure fuel system with a fuel filter, regulator, and return line and a way to get the fuel out of the tank like a sump.  Lots of ways to do this as the Fox Mustang guys have been doing this for years with Aeromotive pumps and the like.  You can score a set of factory Mustang fuel injector rails and install a good regulator on that. From there Aeroquip and Russell both make fittings that will connect to the stock fuel rails and allow a guy to run the Teflon lined braided fuel lines back to the tank.  So lots of ways to get fuel from the tank to the motor.

The aftermarket harnesses will have a fuel pump turn on wire or possibly even include a relay then all you have to do is wire that up to the fuel pump.

Things like a clutch switch to interrupt the start circuit so you cannot start the car unless it is in neutral is up to you.  My '83 does not have this as I just did not wire it in.

If you need the Factory wiring diagram for your car I have one scanned up and can email it to you.

83 351W TKO'd T-Bird on the bottle

93 331 Mustang Coupe - 368 rwhp


Re: 83 v8 thunderbird efi swap

Reply #6
Perhaps it was different in my 2.3T swap, but it was also EEC IV and I don't remember any odd shenanigans with the dash harness. Sure there are connections to be made for idiot lights, etc, but nothing too deep.

It was however almost 20 years ago when I did it, and my notes are kind of spotty, but the non-2.3T dashes in the '83-'84 cars are pretty basic.

Whatever harness you start with, you'll just need to pare it down to what you need.

I used an old factory harness when I did the original 2.3T swap, but built a new one when I did the MegaSquirt install later.

If budget allows, a new, fresh harness is nice, but sometimes you have to work with what you have.
Long live the 4-eyes!  - '83 Tbird Turbo