What do I need to change in my 1985 olds Cutlass supreme to change aa 307 to a 305

Asked by Dan Dec 06, 2015 at 09:20 AM about the 1985 Oldsmobile Cutlass Supreme

Question type: Car Customization

My Cutlass has a blown 307 in it and I can
get a 305 cheap that is ready to go pretty
much just need to know if I have to change
my transmission and motor mounts to do
this? Or will everything for the 307 work

7 Answers

223,695

She'll bolt right in there, but set it up as the old motor is.

1 people found this helpful.
Best Answer Mark helpful
223,695

That could be different, Oldsmobile vs Chevy... It still might, I can't remember at the moment, If it bolts in you will be fine. If you can, it would be wise to compare the two looking for any differences before doing anything.

1 people found this helpful.
223,695

Ok finding out a few things, what side of the 307 motor does the starter bolt up to? The driver side? If so the Chevy motor will not bolt up. I went back to my archives...

1 people found this helpful.
103,035

I think the battery, fuel line, starter are on opposite sides. Up until 1981 Olds Cutlass' could have a factory-installed Chevy 305, after that came only with Olds engines. It will bolt in, and you should have the multi-pattern bellhousing so it should bolt up, the wiring harness is nearly the same, other than the battery/starter being on different sides, you'll have to make some modifications.

2 people found this helpful.
223,695

Putting in a Chevy 305 AND transmission can be done with a lot of work, The cross-member doesn't line up and and the drive shafts are different lengths. The Chevy will not bolt up to the Olds trany.

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