20k Valve adjustment necessary?

Discussion in 'Parallel Universe' started by selecus, Sep 21, 2011.

  1. itsatdm

    itsatdm Long timer

    Jun 19, 2004
    Nor Ca.
    Could be that they were not set to spec in the first place. Better to loose than to tight.

    All parts wear. Cam lobe or wear on the follower would result in increase clearances.

    The valves live in a pretty harsh environment. High temps, high RPM plus containing basically an explosion causes them to wear also. The valve seat is usually forced into the engine block over time, all would decrease clearances.

    So it could go either way, but typically they decrease and fall within the range of normal, unless it happens in a short period of time or the engine loses compression.

    I do not know if there is some peculiarity to this design, but in principal it appears very similar to my TDM 850 with its shim on the valve stem and the bucket being placed over it for the cam to ride on. The clearances always got smaller. Sounds like it wears like that design, as there was very little movement of clearances.
  2. bumbee800

    bumbee800 Been here awhile

    Apr 11, 2009
    Vancouver Canada
    correct my bad. The only way the valve clearance can DECREASE is if the valve is pushed up further into valve train;

    One mistake many people make when checking their valve clearance is checking the valve clearance when the engine is not completely cold. You should only check valve clearance after the engine has been sitting over night. You will see a decrease in valve clearance if you check your clearance when the engine is warm due to expansion. The other way you can get a false reading is checking the valve clearance slightly off of TDC which can also give you incorrect valve clearance.

    I stand behind my own experience and common sense that the valve clearance will always increase with mileage due to wear between the cam lobes and cam followers.
  3. uraberg

    uraberg whosaberg?

    Apr 21, 2009
    Buffalo, NY
    I apologize, I was talking about shim under bucket type valve trains. I guess I need to look better at which subsection of the forum I post in...

    In my experience, the clearances (of shim under bucket type systems) always decrease over time, mostly because of mild tuliping of the valve. The change this causes just seems to overshadow any wear on the valve stem, or the cam lobes.

    In any case, my response was not appropriate for the thread.
  4. JRWooden

    JRWooden Long timer

    Jul 5, 2008
    The great state of confusion
    Old thread I know, but ... I'm curious ...
    What did you find in terms of lash increasing or decreasing on the 800?
  5. Indy Unlimited

    Indy Unlimited Long timer

    Jan 21, 2007
    Parker, CO
    39,500 miles and one of my exhaust valves is just slightly tighter than spec.
    First time I have had to make an adjustment in all those miles. Very happy.