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Valve Clearance too big

Discussion in '70-Series Tech' started by AfricaPhil, May 17, 2018 at 11:03 AM.

  1. AfricaPhil

    AfricaPhil

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    Hi guys,

    Greetings from Central Africa.

    As part of a rebuild of my HZJ75 1996 troopie with 300.000 Km checked valve clearance yesterday after engine rebuild including a new cylinder head (old one had cracks from overheating). the clearance is far too big for all my valves (between 1 and 1,4mm), and I would need new shims between 3,45 and 3,8 mm. They do not even exist on the market in this size. Engine has not been started yet after the rebuild.

    Anyone knows this symptom? What could be the reason?

    Cheers

    Philipp
     
  2. 44Runner

    44Runner

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    Are you sure you are measuring the valve clearance properly? Starts on EM-19 in the manual.

    I would pull some of the shims and check for thickness. See if they are within spec themselves. The smallest they come is 2.35mm that I know of. Also measure the cam and compare to factory specs.

    If all that checks, I would call whoever you bought the head from and get your money back.
     
  3. jblueridge

    jblueridge SILVER Star

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    The valves and everything in the new head are new?
     
  4. AfricaPhil

    AfricaPhil

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    Thanks for the replies. Everything is old but the new cylinder head.

    I looked some more into it. Only plausible explanation is that the new cylinder head from the People Republic of China is not 100 percent exact. Getting the money back is not an option because first, I am in central Africa and business doesn't work like that here and second then I do not have a cylinder head anymore at all. Not too many options here.

    What I could do is having one mm milled of the cylinder head valve "holes". But again, I am in central Africa and doing work in 0,1mm ranges is not particularly the strength of locals... So I might up ending just leaving it like it is. One mm too much is at least better than 1mm to little... A bit frustrating though to have such an obvious mistake after a complete engine rebuild...
     
  5. bj70cruzer

    bj70cruzer

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    I would be checking how the valve seats were cut and measure the installed valve heights.
     
  6. jblueridge

    jblueridge SILVER Star

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    I think skimming the mating surface of the head would make valve lash less.