2.5 4 cyl to 2.8 rwd swap, harness ??

[zombiedeth]

hey guys, i have a 86 s10 shortbed\cab 2wd with the 2.5 and 4 speed auto. I really wanted a stickshift truck, but i got a good deal on this truck and its in decent shape. I picked up a parts truck, a 90 2wd shortbed\cab with the 2.8 5 speed. the 2.5 i have in the car has 175k on it, the 2.8 has about half that, plus im thinking it would be easier just to pull the motor and tranny as a complete unit. the 90 was hit in the front, and the frame\cab is tweaked so theres no way I can just fix it and drive that one.



my question is, how interchangable are the wiring harnesses? being that theyre both tbi systems, i would imagine they should be very similar, if not identical. would i be able to swap the motor and just hook the 2.5 tbi harness up to the 2.8 and just switch the computer at the other end?



if not, the 2.8 engine harness should just be plug and play where it meets the body harness right? i shouldnt have to manually splice anything seeing as they are both from s series pickups right?



i tried searching and mostly all i come up with is people asking about the swap and others saying it isnt worth it for the power increase you get. i would agree under normal circumstances, but i have both motors already in 2 complete running trucks so i wouldnt have to outsource any parts. also, if i did this i would probably build a 3.4 to swap in at a later date. any input is appreciated, thanks guys!!

[geoffinbc]

The harnesses are very close. But I think it would be quicker to swap the 2.8L harness. Do yourself a favor and get a GM service manual and confirm the wiring is the same at the bulkhead plug. Chances are they are the same. You could compare wire colours on every pin and that should confirm the theory also.

The reason I say switch the harness is the wire lengths and the 2 injectors for the 2.8L will require modifications. So if you have a ready made harness then use it.

[neo71665]

asking all over the place are we, lol.