Compression test numbers..?

Discussion in '40- & 55-Series Tech' started by Bennett, Jun 27, 2005.

  1. Bennett

    Bennett

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    Ran a compression test for a friend today on a mid 70s 2F. He has a receipt form the previous owner showing a rebuild ($2500) 15k miles ago.
    The truck really runs fine and has no oil consumption.. I pulled all the plugs and open the throttle plate and turned it over 10 times on each plug.

    Here is what I got..

    110 110 110 110 105 110 dry

    110 110 110 110 110 110 wet (oiled)...

    thinking I had a bad gauge I tried another and got the exact same readings.
    I am thinking I have good tight rings but 110 seems low?
    I put a borescope in each cylinder and very clean wtih no carbon buildup and cross hatching on cylinders still visable.

    why such low numbers and is there reason for concern?

    thanks
     
    Last edited: Jun 27, 2005
  2. Poser

    Poser Oh...Durka Durka Durka. s-Moderator Supporting Vendor

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    Adjust your valves and try again....
     
  3. Bennett

    Bennett

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    What would be an acceptable psi range?
     
  4. honk

    honk

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    Maybe retorque the head, but tight valves will do that..

    Different guages do often give different results but you said you tried two. Are you using the type of guage with a push in rubber sealer? Those suck - the screw-in type with a good o-ring gives better results.
     
  5. Bennett

    Bennett

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    they were good hasting gauges with O- rings...
     
  6. Pin_Head

    Pin_Head

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    If it is not the gauge and the valves aren't leaking on every cylinder, maybe the PO used flat top pistons when he should have used domed ones. I am not sure that this would account for the compression numbers. If it runs fine and it doesn't burn oil, I wouldn't lose any sleep over it.
     
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