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Engine Questions - Timing and leak down/compression related

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  • Engine Questions - Timing and leak down/compression related

    Today I was checking the timing of my car and in 4th gear at 4000rpm, my timing was at 45 degrees. Is this normal or too advanced? I am using a JC chip (91 octane california chip) and the Maxx Alpha N unit. What are you guys seeing for timing? I want to swap out my JC chip for the stock chip to see if there is a change because 45 degrees seems a bit high. :cylon:

    Also, I did a leak down and compression test on all four cylinders. The engine has stock cams (2.3l) and just turned over 83,000 miles (zero internal engine work to date).

    Leak down:
    Cylinder #1 = 87
    Cylinder #2 = 93
    Cylinder #3 = 74
    Cylinder #4 = 73

    Compression:
    Cylinder #1 = 205
    Cylinder #2 = 206
    Cylinder #3 = 190
    Cylinder #4 = 185

    On the leak down for cylinder #4 we could hear air escaping from the dip stick tube so it seems like a piston ring is not sealing as good as it should be.

    How do these numbers stack up? Is it possible to just pop open the engine and replace the piston rings? Or the dreaded, "what else should I do while I am in there question"? Should I not do anything and wait?

    Thanks for any feedback.

    - gabor
    October 1987 build date.

  • #2
    Not sure about the timing...but I wouldn't tear down the engine for those numbers. The S14 isn't known for bore wear or ring wear so it likely isn't a problem that's going to get worse. I would get routine oil analysis done though because that will pick up ring and bore wear and the much more likely rod bearing wear.
    "It is needless to say that self-propelling vehicles, like other machines, will never do as much for one who does not understand them as for one who does."

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    • #3
      I agree... on compression... all cylinders should be within 10% of the highest measurement. 10% of 205 is 20.5 and your #4 cylinder is just within 10% ..

      it's possible you may be catching an early head gasket issue as 3 and 4 are both down from the other cylinders, but I would not go
      tearing into the motor if it is working well for you.
      Last edited by M3 Adjuster; 12-23-2007, 08:33 PM.
      Mark Williams
      Dallas, TX

      Nothing says "welcome to the neighborhood" like a search... oh wait... looks like they are all gone! :rastajake:

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      • #4
        Fair enough. THank you for the replies. I will have to keep an eye on this one.

        I will def. get an oil analysis done too. Great idea!

        - gabor
        October 1987 build date.

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        • #5
          45deg ign advance is normal for 4000rpm an no load. As the load increases this will drop to about 20deg at WOT.

          Steve
          Sport Evo No.47

          My Sport Evo Restoration

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          • #6
            I did a valve clearance check today and it looks like my exhaust valve shims are out of spec for pistons 3 and 4. I ordered new shims at the dealer so i hope this will correct the leak down numbers a bit.

            - gabor
            October 1987 build date.

            Comment


            • #7
              The only way it will help the leakdown numbers is if there was 0 clearance between the cam and the shim
              "It is needless to say that self-propelling vehicles, like other machines, will never do as much for one who does not understand them as for one who does."

              Comment


              • #8
                oh yeesh, you are right. Regardless of shim thickness, the valve would be closed. Slipped my mind.

                -gabor
                October 1987 build date.

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