I have a customer that wants to swap his V-6 out for a small block V-8. He has an 85 Cutlass supreme with the V-6. He has an 81 Cutlass Supreme with the V-8. He wants to put the 81's V-8 into the 85. Are the bolt patterns the same? My AllData program doesn't cover back to 81's. Any information will be greatly appreciated. You can email me at themobilemechanic@comcast.net

 

Gosh, my experience doesn't go that new 81, 85 that's like yesterday.
If you don't get any info here try a G body site, they might know....Good luck.

 

There were some changes in those years, but I don’t remember when the changes occurred. What transmissions are in both cars? If they are both the same transmissions then the patterns will be the same, provided are rear wheel and both are carbureted engines. One can’t be throttle body and the other carbureted because you will have computer problems. With a throttle body vehicle the computer will not allow for the change.