Olds 260 to Buick 350 Engine Swap

Discussion in 'Wrenchin' Secrets' started by concialdi, Feb 13, 2021.

  1. concialdi

    concialdi Member

    Years ago I started an engine swap and pulled the factory Olds 260 out of my 75 Buick Skylark and rebuilt a Buick 350. I stopped the project for probably almost 10 years but now want to get that engine in and fired up.

    I have put the 350 into the car and on the motor mounts but it looks like it is not lining up with the bell housing. This is my first engine swap so forgive my ignorance but shouldn't the 350 line up just like the 260 did? Do I just need to put some muscle into it and line up the tranny and engine? It looks like the engine is sitting a couple inches too high and forward of the tranny.

    For reference the car is a 1975 Buick Skylark S/R, auto trans.
  2. Max Damage

    Max Damage I'm thinking about it!

    I have no experience with that particular situation, but I believe all Buick, Olds, Pontiac transmissions from that era should cross? Does it look like the bolt pattern is different or is the back of the engine in the wrong location?
  3. concialdi

    concialdi Member

    Thanks for the response.

    I thought the same thing about the BOP from that era. It looks like the back of the engine is in the wrong location.

    I will say I have not tried to start moving things but it just looked off to me.
  4. sean Buick 76

    sean Buick 76 Buick Nut

    Hi, what you need to make it bolt in properly are two things:

    1. 73-74 Skylark buick 231 v6 or 350 frame engine mounts

    2. 73-74 Skylark 231 or 350 engine mounts.

    100% the trans bolts up perfectly fine. No need to move anything there. Remove the engine mounts off the engine and lower it in and you will see where the engine mounts need to be.
    Last edited: Feb 15, 2021
    Mark Demko and GS464 like this.
  5. 1972Mach1

    1972Mach1 Just some M.M.O.G. guy.....

    It should bolt right in with the correct frame/engine mounts. Your trans is probably sitting nose down if you just have it resting in there with only the tranny mount holding it up. You can put a floor jack under the trans bellhousing to raise it up where you need it, but use common sense and don't get nuts if you feel resistance. One thing I will note, your trans is likely a TH200 (not a 200-4R), and it'll probably live a very short life if you don't go easy on it with the new 350. I had one behind a stock Olds 350 for a few years, and it was starting to slip when I sold the car. Hot rodding on it will give you the new experience of a trans swap, too.
  6. Mark Demko

    Mark Demko Well-Known Member

    Follow Seans directions. the Olds and Buick are two different engine designs

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