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Narrowing Main Bearing Caps

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  • #16
    but wonder whether he had it right to fit and torque then bore?
    This is the correct procedure since this will be as the engine operates when assembled.
    Home, down in the valley behind the Red Angus
    Bad Decisions Make Good Stories​

    Location: British Columbia


    • #17
      Originally posted by paul463 View Post

      Line boring isn't going to make that cap and block in the photo work together. It's waaay too offset to one side. Unless it fits closer
      turned around.
      That was my first thought having worked in an engine building shop and having line honed many blocks. There is just no way that will ever cleanup.


      • #18
        He said in the first post they would be turned 180 degrees.


        • #19
          Think about what you want as a result. Make some decisions about cost. Find a machine shop that you are comfortable with and has a good reputation. Talk to them about your plans, more than once if you are serious about them. Listen to what they say needs to be done, how they will do, and why they say it should be done. Educate yourself. Line boring in an automotive machine shop is actually called align boring (or honing). The objective is to place each journal at the same height and roundness. Typically, some of a well used engine's main journals will show wear, which means they are no longer round. This means the caps have to be ground to hold the bearings and provide correct oil clearance. This is done before boring. The clearance target is not the same for casual driving vs. high performance driving. This is why you need to talk to the shop. Once the block is align bored it will be align honed to fine-tune the journals.