I am a 2nd generaion owner but just bought 2 3rd generation cars. My question is can I switch the motor and tranny from a 1991 191ci v6 LHO with manual to the 1985 173ci v6 LB8 with auto.
I am woundering if the harnesses will inter change?
This is a project I would like to do with my son and want to know if it is possible.
Thanks for the replies Shawn

 

Yes, but is most bestest if the you have the donor car for the 2.8.

 

It really depends on which parts you're using for which cars.... The ECU harnesses are completely different in both, serpentine vs V-belt (two different oil pans, front covers, and water pumps), internal vs. external balance (flexplate/flywheel are not interchangable), etc etc...

Really need to know more to give an accurate labor estimate... and the way you worded the question leaves me with no clue which engine you're planning into swapping into which car with which transmission...

 

Also depending on the smog laws in your state you may not be able to put the engine from the 87 into the 91, but you would be able to put the engine from the 91 into 87. California smog laws state you can use an engine from the same year or newer, but there is no visual difference between the 3.1 and the 2.8 blocks, but they will be able to spot the fact the 91 has V belts if you put the '87 2.8 in the '91.

More states are moving towards adopting Clifornia smog laws. Your local DMV or in some cases your state web site may have more information about what can and can not be done as far as engine swaps.

Also other then what was metioned above one of the temp sensors is in the rear of the pass side head on the 2.8. On the 3.1 it's on the front drivers head. So you would basicly need to swap these around unless you are swapping the wire harness as well.

I'm not sure if the '87 2.8 had a cold start injector or not, but I know my 3.1 does not. made need to swap fuel rails around to make things function correctly.

I would get a shop manual for for both years so you have something to compare the two with before starting, or if you can take your time doing this just around here when you run into a stumbling block.

Most differences are minor and can be worked arund easily. I think it would be a great project as it would help foster good problem solving skills. Some thing a lot of kids growing up today lack.

 

Thanks for the replys, my original plan was to switch the motor from the 91 into the 85, after talking to my son he believes he would rather have the 91 rs. We will leave the motor in this car since it had a recent overhaul and new clutch installed. I have completly redone his 85, including the body work and paint. Someone had changed the MPI to carb and it is now somewhat of a dog (V-Jet carb is junk). Here is the 85 after I had redone it, but looks like I will have to start again and do this all to the 91.
Thanks again Shawn