exactly what harnesses

jeremey thomas · Aug 27, 2006

doing a 5.0 swap on an 89 coupe.already have a engine/computer harness from a 89 gt.what else do i need?
ive had a few people say thats it,but some say if i dont change the dash harness i will burn up the computer. one person even said i have to change it all, light harness,engine harness,dash harness,and main body harness all the way back to the fuel pump.anyone else done this swap? ive done a carbd swap without problem but i want to inject this one.please someone help.

jeremey thomas · Aug 28, 2006

v-8 swap guys unite help me please

NFGTragedy · Aug 28, 2006

The list tends to get big if you want to do it completely.

motor
harness/computer
motor mounts
fuel lines -- 4cyl is drivers side, 5.0 is passenger side
fuel pump -- though i've heard of people running the 4cyl one.. not me.
tranny -- if aod you need the linkage, tranny, and a shifter
double hump crossmember
passenger side exhaust hangers
dual exhaust
brake lines -- though i've heard you can modify them with a few splices
8.8 rear -- if you don't want the 1 wheel peel.
quad shock brackets -- if you want to run them
5.0 sway bars
pinion snubber
front spindles -- if you want the v8 style brakes, now would be a good time for a 5lug conv also
brake booster/mc -- 4cyl came with a smaller booster minus the verts.
You will need to extend the alt harness also as the 4cyl comes up on the drivers side and the 5.0 alt is on the passenger side.

I'm sure i'm missing some other small stuff but thats basically all I can remember right now.

bullitstang1313 · Aug 28, 2006

The dash harnesses are the same between the 4 cylinders and the 5.0's. You can either change the headlight harness or just extend the alternator wiring.

RsStanG1987 · Aug 28, 2006

bullitstang1313 said:
The dash harnesses are the same between the 4 cylinders and the 5.0's. You can either change the headlight harness or just extend the alternator wiring.

They dont work together ive been there and done that before. Your better of getting all the harnesses from a v-8 car.

superhuaman · Aug 28, 2006

RsStanG1987 said:
They dont work together ive been there and done that before. Your better of getting all the harnesses from a v-8 car.

mine works fine, but of course i got the same year v8 harness. i had to run a couple wires, so i could keep the 2.3 fan controller running my electric fan, but that was all.

TC93 · Aug 30, 2006

The 89 engine harness will work fine with and 87-89 dash harness. You will need to swap the tach for a V8 tach or swap cluster from an 87-89 v8 car.

And like mentioned above can use the 4cyl light harness and lengthen the alt wires or swap for a v8 hanress. Also need an 02 hanress froma v8 car...

jeremey thomas · Aug 30, 2006

so since my 89 coupe im using an 89 v8 harness i shouldnt have to change the dash or chassis harness.only the ecm/engine and headlight/alternator

superhuaman · Aug 30, 2006

on my 90, the 2.3 alternator harness came out completely seperate from the headlight harness. has its own fuse link and everything. only one wire goes from the alternator harness to the dash harness. the rest, go to that fuse link.

jeremey thomas · Aug 30, 2006

what year is your car?did you encounter any other problems that i should know?

jeremey thomas · Aug 30, 2006

what year is your car?are ther any other problems i may encounter?

superhuaman · Aug 30, 2006

its a 1990...its kind of hard to understand how the wires between the dash and engine harnesses match up, especially with regards to the A/C. but remember, the 5.0 doesn't have an electric fan, unless you added one. i know i had to run a couple wires, because i have a volvo fan hooked up to the 2.3 electric fan controller, and i wanted to keep it working. so i had to tap the 5.0 a/c circuit so it would activate the fan with the a/c. i like the 2.3 fan controller because of its time-delay, to help with electrical loads.

but if youre using the mechanical fan, dont worry about all that, just plug it in and go.

jeremey thomas · Aug 30, 2006

sorry for the double post the first didnt show up on my computer

jeremey thomas · Aug 30, 2006

cool sounds good,thanks alot.

superhuaman · Aug 30, 2006

it's alright. the extent of my custom wiring is limited to the cd player, shifter light, accel ignition box, electric fan, and various grounds. everything else plugs in like it is supposed to.

superhuaman · Aug 30, 2006

no problem, glad to help.

TC93 · Aug 31, 2006

jeremey thomas said:
so since my 89 coupe im using an 89 v8 harness i shouldnt have to change the dash or chassis harness.only the ecm/engine and headlight/alternator

Right.. All you need to do is add the engine,, injector, and 02 harness. And can either swap the light harness in or lengthen the alt wire to reach the P-side of the car.

But will need to swap fuel lines or modify the 4 cyl ones to work for a V8..

Also stuff that an be done but don't have to for the car to run & drive......

Swap front brakes out for 5.0(v8) stuff, swap 7.5 for 8.8, swap out body brake line so you can run tail pipes. If you run turn downs the 4cyl brake lines will be fine. But if ypu want tail pipes, need to swap to v-8 body brake line, because of where the back body brake lines connect to the axle lines..

superhuaman · Aug 31, 2006

im not sure...i think i may have solved the 4 cyl brake line problem. the bracket where the brake line goes to the hose, is located where one of the exhaust (muffler) hangers needs to be. but the way i have the hose routed, it should not be in the way of the exhaust pipe going over the axle. i have seen some cars, in particular a 98 v6 with dual exhaust, where they left the rubber hose in the stock location. it was close, i wouldnt recommend it for long, but it was still ok when i saw it. here's my car:
View attachment 443866

superhuaman · Aug 31, 2006

if you swap the brake line, you need a special bracket and adapter (discontinued) to attach the tubing to the hose above the axle.

jeremey thomas · Aug 31, 2006

well i guess since i already have the ecu/engine harness in i will go ahead and drop the motor and everything in and see what happens.i mean worst case scenario i lose an ecm right.anyway what about the fuelpump,do i need to change it?i dont know what size the 4cyl is but i would think it would be way small.
next question this car came from lower al.but has some kind of black goo from one end to the other,but none in the engine compartment.some of it is hard and brittle and chips off easy but the rest seems like in the heat of the summer it has almost turned to tar.i usually clean the underside of my project cars before i get started as you wouldnt believe the amount of weight loss just in getting the dirt out of certian cracks and crevices,but i have never seen anything like this.

exactly what harnesses

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