QuestionI have a 87 Buick Regal with a V6 I don't know the exact CID, But I would like to replace the old motor with a 307 V8 out of a oldsmobile. Would I need to also buy a new tranny or is the existing tranny compatible? What other modifications would need to be made to make this work. Will the starter and A/C compressor from the V6 connect or will have to buy new one's. I need this done ASAP. So your insight is greatly appreciated since I'm a back yard mechanic and I'm doing this on my on. Thanks for your time.
Answer You can do this, but the extra parts you need are going to depend on what the 307 came out of. It WILL bolt to the transmission, but you will need the appropriate flexplate to go with it. The starter is different, but the A/C compressor is the same, if we are talking about the same year car. If not, all bets are off. You will need the appropriate brackets to mount all of the accessories. It's really the front of the motor that is going to be the problem. If you are taking the motor out of a G-body car (Regal, Cutlass, Grand Prix) then you will want to get the engine mounts and the brackets that go with them. You should be able to cobble the rest together, although getting it to work with the computer in the car will be impossible, you will have to use the computer out of the old car. If this engine is missing parts, and you have to scrape together all of the accessories and brackets, manifolds, pipes, etc., then you would be much better off buying a rebuilt 3.8 and going with that. Plus, depending on where you live, the swap may violate the state emission and inspection laws, making the car impossible to sell when the time comes. The 307 does have better torque than the V-6, but not a lot more power, I think you would be disappointed if that's why you are doing it. If you're looking for a power increase, and don't care about the emission laws, a bigger Olds or Pontiac engine would make more sense, say a 400 or 403. If you don't mind buying or swapping for another transmission, then go with Chevy power, it's always been the most bang for the buck. If you have the overdrive trans with the 3.8, it's worth more than a Chevy trans, as B.O.P. (Buick-Olds-Pontiac) overdrive trans are hard to come by, and a lot of guys hotrodding older Pontiacs, Olds, and Buicks will pay good money for that extra gear.
