'77 Cutlass Supreme 4 door, engine compatibility?

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Well, the title says what I've got, it has the 350 GM Rocket in it. Now, it's only got 105000 miles on it, but there are leaks of one sort or another (little coolant, quite a bit of oil that is burning up on the outside of the engine)

I was wondering if a 350 that fits in a GMC Rally STX would be compatible with my car? The Van is headed for the junk yard, but the engine/carb are only 3-4 years old (20000 miles on it) And I can have it for free.

Am I smoking out the wrong end of a tailpipe, or is this possible? I've only taken a quick look at the GMC, and the mounts appear to be in the same orientation.

posted by  Millsy

Yep, that engine should fit your Cutlass.

posted by  theman352001

I've been asking around, and I get a lot of different opinions on this the last few days.

Some, like you say that it should fit, no problems. Others say nothing will be compatible and I'd have to replace everything else.

Is there anywhere I could go to find out more information about this? Like will I have to get an adaptor for the tranny? What about electrical lines and such?

posted by  Millsy

GM 350's are pretty universal. You may need to put your Cutlass's engine mounts on the new 350 but otherwise there should be no problem. As far as lines are concerned, it is easy to make new ones if needed. You just need to know which one goes where.

There may be some changes also in the computer or ignition controls. You can choose which one would be better in the long run and use that one.

The only other issue you may have is smog related. If you have to pass smog inspections then you need to ensure that the emission controls on the new motor are as-good-as or better than the ones on the old motor.

I would suggest getting the engine out of the van first and then really taking a look at the differences. I doubt there will be much.

posted by  theman352001

Smog controls.. heheheh I'm in Canada, (Alberta specifically) so no testy here. :)

The differences others have mentioned is the bell housing won't match.

I really wish there was an online source for the blueprints and such :\

posted by  Millsy

Me too. You could try picking up a GM casting numbers book. I have been meaning to get one but haven't yet. It should provide you with enough information to tell if the 2 engines share the same bell housing bolt pattern.

Anyway, you can get around the whole bell housing issue if you swap engine and tranny together.

posted by  theman352001

Tranny on the van is compleatly hooped. main reason it's getting the boot. Not worth it anymore to fix.

Where would I order the book from?

posted by  Millsy

You can google up some info. I typed in "GM casting numbers" and got a bunch of info. You may also want to try "GMC" and "Oldsmobile" with "casting numbers".

It has been brought to my attention recently that there may be some differences between the 350's your trying to swap out. It really depends on what is in that Cutlass and if it will be compatable with what you have in the van.

One way is to research both engines using the casting numbers to find out what you have. Then you should be able to research if they are compatable.

The second way is to remove both engines and check them out. Of course the problem here is if they are not compatable, then the Cutlass is out of commision for a while. Although you could always drop the motor back in again.

posted by  theman352001

The problem is the transmission match-up. The bell housings are completely different shapes. The chevys have a peak at the front, whereas the olds has a dip. They won't match up without a special adapter. Your're better to try to find another olds engine.../mkf

posted by  freeman437

There is an adapter plate available through summit racing so a chevy engine can bolt to a olds trans (and vice versa). A buddy of mine is going to be dropping in an Olds 455 into his 75 Monte Carlo and will be using the MCs tranny. The Summit Racing Part #: TCI-230000. The description reads:

"These high quality adapters from TCI allow you to connect your Chevy engine to any B.O.P. (Buick, Oldsmobile, Pontiac) transmission, or a B.O.P. engine to any Chevy transmission."

Hope this helps.

posted by  76MonteMan

youll have to change motormounts cause the olds and chevys are different. and if you change that you might have to move the crossmember a little cause i beleive the chevy sits farther back so youll probably have to move the crossmember. some olds had unibell transmissions double check to make sure it doesnt bolt up to the chevy motor. if you need help i know a demolition derby guy who makes BOP adapter plates 50 bucks plus shipping IM me and i will give you his info. i have one and it works awesome.

posted by  adamc44

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