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Thread: Will 231 heads fit on a 252 block??

  1. #1

    Will 231 heads fit on a 252 block??

    Its time to build my next engine, but I cannot decide what to do with my garage full-o-parts! I'm contemplating a 252 build instead of the usual 231. I have a complete set of '83 231 heads, and I'm trying to figure what to put them on!

    Will they physically fit the 252 block (I'm guessing so), and what will the result do to the compression ratio??

    I gotta think that the heads have different chamber sizes, so will I bump the compression too much? from what I've read so far, the original CR is about 7.9:1. So I should be safe with a bit of a bump at least a point and a half- right? Anybody try this?

    I'm trying to build a totally street engine- it will NEVER see 4100 RPM (due to the auto trans). I'm planning to use a slightly hotter than normal "turbo" cam to give it ordinary street manners, but this should still allow it to breathe well.

    Any comments are welcome- chime in!!!! Gimme some ideas!!! thanx!
    "Stanley" keeps on putting along.....ya gotta love the old man vibe from this 4dr Century!

  2. #2
    http://www.gnttype.org/general/v6hist.html

    That link provides a bunch of casting numbers for the Buick V6's. It shows the same casting number used with the 3.8L (231) and the 4.1L (252) engines. Most people will agree that the casting number ending in 8445 is the best flowing head for these engines from the factory. Also the same heads were used on the naturally aspirated engines and the turbo engines. So I would feel completely comfortable bumping up the compression ratio. These engines have a huge following between the turbo engines and the Jeep fans. Tons of info on them available at www.turbobuick.com and www.gnttype.org.
    Project car + budget = headache.

  3. #3

    thanx

    thanx for the links- I apparently didnt search hard enough....yep, after a bit more checking- it appears that the heads are interchangeable. So now my next question is what type of piston should I find to bump the compression to 8.5-9??? I'm under the impression that these came stock at 7.9:1

    Anybody play with the 252??
    "Stanley" keeps on putting along.....ya gotta love the old man vibe from this 4dr Century!

  4. #4
    Anybody play with the 252??


    that's actually old tech. the 252ci / 4.1L was the basis of the NASCAR Busch v6 that terrorized the circle track world in the 80s.


    http://www.teambuick.com/reference/l...aker_buick.php

    i think this Baker Engineering is the same company:
    http://www.bakerengineeringinc.com/
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  5. #5
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    The 252/4.1 is basically just a 231/3.8 with a larger bore. All the other parts are the same. The block you have will need to be magnafluxed inside and out. If I remember right these had a bad habit of cracking between the freeze plugs on the outside of the block. You will not find many off the shelf pistons for these, other than stock replacements, you will need to have them custom made. Your other choice would be to get stock replacements and see how much you can deck off the block to get "zero deck" and figure out how much compression that will add/ The turbo guys use this block sometimes and probably some pistons are made by turbo specialists but they are usually fairly low compression so they can use more boost. Custom pistons usually run about 100$ a hole. If your down with spending that much you can get about anything you want. I would not use a cam designed for a "turbo" application. Call any of the major cam grinders and say you want a maximum low rpm torque cam if you are never going to rev it. A turbo cam and a regular cam are designed very differently. All the torque increase from a turbo engine comes from the turbo not the cam.

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