Olds 260 replacement

DP in OC

n00b
Jun 9, 2024
1
0
1
I have a 1981 cutlass with a V8 260 engine. I was wondering should I replace with a olds 350 or 455? I know I am going to have to replace the transmission. Without having to make a lot of modifications, will a olds 455 drop in engine bay without modifications and can I run ac? Thanks
 

69hurstolds

Geezer
Supporting Member
Jan 2, 2006
8,321
17,978
113
To choose between them, you'll be miles and smiles ahead if you put something in that FITS with virtually no modifications, such as the 350. Looks the same dimensionally as the 260, yet is way better on performance.

As far as build, you can do anything your heart and wallet desires. Issue with BBO in the 78-88 Cutlass is that there's limited room under the hood to do anything crazy like tall intakes, spacers, etc. with a 455. Unless you start cutting hood holes or buying scooped hoods, just adding to the expense.

Can you do it? Sure. But you'll need to modify some A/C brackets if you want to keep your original pulley setup, etc., with a 455, or just swap them over to a 350, for example. Put a TH350 behind it, and you're set for a great fully streetable situation.
 
  • Like
  • Agree
Reactions: 6 users

doood

Amateur Mechanic
Sep 24, 2020
620
862
93
People have suggested the 78-ish 403 (trans am motor) 200hp - they are on the marketplace. Pre 1976 350 would be a good find.
 

78Delta88

Royal Smart Person
Supporting Member
May 23, 2022
1,304
1
1,096
113
SW Arizona
I did back in early eighties. Last one i did was 78 or 79 cutlass. Pulled the 260 and trans, and replaced with 350 and th350 out of a 73 Custom Cruiser. Everything was basically plug and play.

Visually looks the same. Nothing needed changed. Car was console shift so cable hooked and up fine, drive shaft yokes were the same, crossmember the same.
 
Last edited:
Oct 14, 2008
8,840
7,808
113
Melville,Saskatchewan
The A/C brackets will not fit on the BB 400 through 455. Also a factory air cleaner will have issues. Either an Olds 350 or 403 with a short tail TH350 will bolt right in. A 2004R requires frame extensions on a 81, I believe.
 
  • Like
Reactions: 1 user

buick7332

Master Mechanic
Oct 21, 2014
353
597
93
N.E. Philadelphia area
I did back in early eighties. Last one i did was 78 or 79 cutlass. Pulled the 260 and trans, and replaced with 350 and th350 out of a 73 Custom Cruiser. Everything was basically plug and play.

Visually looks the same. Nothing needed changed. Car was console shift so cable hooked and up fine, drive shaft yokes were the same, crossmember the same.
In the early eighties that was the very first engine swap I did. 79 Cutlass with the 260 to a Rocket 350/ th350. Everything just fell right into place like it was ment to be there.
 
  • Like
Reactions: 1 users

GBodyForum is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. Amazon, the Amazon logo, AmazonSupply, and the AmazonSupply logo are trademarks of Amazon.com, Inc. or its affiliates.

Please support GBodyForum Sponsors

Classic Truck Consoles Dixie Restoration Depot UMI Performance

Contact [email protected] for info on becoming a sponsor