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Questions On Rebuilding A Turbo Block.

Discussion in 'Jeepster Commando and Commando Tech' started by Henry Nachtsheim, Nov 6, 2019.

  1. Nov 6, 2019
    Henry Nachtsheim

    Henry Nachtsheim New Member

    Mar 1, 2019
    I'm rebuilding a 231 for my jeepster, The tech #s show my block turns out to be a "turbo block" early 80s, to get compression up, using flat top pistons I can only find .60 over. My very able mechanic was questioning boring more than .30 over until we discovered the turbo aspect. My question's are; anyone know where i can get .30 over flat tops, or what's the feeling about boring the block to .60 over? Whats the difference in the turbo block than the standard 231 block? Should I stick with my 225 fly wheel? And where can I get a rebuilt odd fire crank? The jeepster is mostly used for running around the island I live on, not over 55' or creeping around the Glades at slower speeds.
  2. Nov 7, 2019

    Dauntless1971 Member

    Bend, OR
    Oct 22, 2004
    It would be interesting to see what the casting numbers of your odd fire turbo block, heads and crankshaft. My understanding is some early turbo engines used the same block as the N/A engines. I figure if you are building a even fire engine, just supply your machinist with the odd fire flywheel and have it balanced with the rest of the parts. Years ago I had a small block Chevy engine built and used flat tops pistons. I have regretted for many years trying to get more horsepower by raising the compression. As mentioned in your other post TA Perforce may be your only choice for a quality piston. Bay Burton may also have something, though it might still be a dished piston since it is designed for use with a turbo.
  3. Nov 9, 2019

    Keys5a Sponsor Sponsor

    Florida Keys
    Jan 23, 2014
    If I recall from your other post, this turbo block 231 came out of a Jeepster parts chassis? I thought you said it was an odd-fire? The main difference between an odd and even fire is the crankshaft its self. The odd-fire rods share the same journal on the crank. The even-fire crank has a "split-pin" rod journal where each rod has a separate offset on the same journal.
    What crank do your have? The early 80s turbo Regal block was an even-fire engine. The 231 odd-fire engines were only used from '75-'77, and they are essentially "bored-out" 225s, with some improvements.
    You should be able to rebuild your 231 with all the stock parts. Often, the crank is fine to reuse with only a minor polishing. Is your 231 block worn so much that it needs a rebore? Does your engine, in fact, have the deep dished low compression pistons used with the turbo, or are they the shallow dish pistons? The 231 shares the same bore diameter with other Buick engines, but using V8 pistons would require machining to account for the offset of the split-pin 231 journal. There was also a 3.0 liter Buick V6 thay shares the same bore, and has the split-pin crank, only shorter stroke. I have heard of using these pistons in a 3.8, but I don't know the pin height. You should be able to just rebuild your 231 with the same parts as any mid-80s Buick 231 out of a naturally asperated Regal. For your purposes, your not trying to build a high-performance engine.
    As far as the flywheel, what did the "parts" engine/chassis have you are trying to use? You could have the machinist re-balance your 225 flywheel, but the Jeep odd-fire part was very heavy (and designed to dampen the odd-fire pulses) compared to the passenger car 231 flywheel, so it is not an ideal candidate, this is all assuming you have a manual transmission. Many Jeepsters came with a TH400 automatic, simpifying the flywheel delema.
    Lots of questions!
    Dauntless1971 likes this.

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