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Valve Adjustment  Check

Discussion in '80-Series Tech' started by landtoy80, May 4, 2003.

  1. landtoy80

    landtoy80

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    I checked the valve clearance. With 220k mi the clearance was:

    exhaust; valves for 1,2,3,4 is .011" 5,6 is .012" range is .010-.014
    intake; 1 is .006 2,3,4,5,6 is .007 range is .006-.010

    With the 1fz motor, it uses shims to adjust. As the motor wears, the clearance between the valve lifter and camshaft should increase, right?
    kurt
     
  2. Guest

    Guest Guest

    Re: Valve Adjustment  Check

    Kurt, as i understand it from christo,the clearance actually DECREASES because of wear at the face(the part that sits in the head) of the valve,which results in the valve face moving UP in the head and thereby DECREASING the clearance between the shim and cam lobe...

    Which is why its an important thing to check and keep on top of......(dont want to burn up a camshaft)

    i hope i am describing this correctly or if i am not someone that does know will chime in :)


    doug
     
  3. Beowulf

    Beowulf

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    Re: Valve Adjustment  Check

    Doug is correct.

    Here is a better explanation from a post by Ralf Vogel about 6 months ago on the international 80s list:


    This is what I have found:
    It depends very much on the fuel in use.
    In GCC, e.g., the clearance normally becomes larger, in USA tighter.
    Why?
    There are two main factors of wear:

    1. Valve seats -- tightening the clearance.
    2. Valve lifters --- increasing the gap.

    In the ideal case, both factors compensate each other and no
    adjustment is needed.

    The fuel plays a crucial role:

    1. Inlet valves:
    A. Use of LPG or very light petrol w/o additives can lead to an
    increased wear of the valve seats --- narrowing the gap.
    B. Petrols with some heavies or detergents protect the seats, wear
    occurs mostly at the lifter --- increasing the gap.

    2. Exhaust valves:
    A. Unleaded fuel w/o valve protecting agents --- wear at the seats
    can dominate --- tightening the gap.
    B. Leaded fuel or petrol with valve protecting agents: wear mostly at
    the lifters -- gap increases.

    3. Other factors: Low quality engine oil and bad air filtering/dusty
    environment can inrease wear in cam, shim and valve lifter area ---
    increasing the gap (inlet & exhaust).

    I have checked my valve clearance at 133K km, two Ex were slightly
    off (too much gap-- typical for GCC, leaded fuel & dust)

    Cheers -- Ralf.



    -B-