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Thread: Hawkeye with 600HP at the wheels...

  1. #161
    Senior Member 2pot's Avatar
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    Quote Originally Posted by daz-davies View Post
    The valves are all going in the bin even the good ones. I'm going Ferrea this time round.
    Wasn't it Supertech the first time?
    Edit: you're right, second time as well
    Last edited by 2pot; 26th October 2017 at 13:38.

  2. #162
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    Quote Originally Posted by 2pot View Post
    Wasn't it Supertech the first time?
    Edit: you're right, second time as well
    if the underlying cause isnt remedied then eventually most valves will fail.

    If you search, you find many threads here and in the US of various valve failures. So it is not limited to one brand. But for every failure, there's no doubt there are also many many running reliably with the same valves.

    So there has to be a cause and the least likely one is actual valve failure due to an actual manufacture problem. Possible...but not likely because it isnt limited to one brand, one batch of valves, etc etc
    speed didnt kill me, but taxation probably will

  3. #163
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    This is why I can't understand this issue.
    None of the remaining valves show sign of any impact damage. The stems show no signs of abnormal wear or any kind of heat build up.
    All clearances were spot on. I bought all new buckets at significant cost to get them absolutely spot on and not just within tolerance.

    Limiter was set at 7800rpm and although I've hit the limiter a few times the engine has never been over revved.

    Yet somehow all the inlet valves have stress fractures. So how it this possible without any signs of abnormal wear on the valves, stems, seats, retainers or buckets?

    There is no other explanation other than the valves were just not upto the job.

    Open to be corrected on that but I just cannot see any other signs of it being anything else.

  4. #164
    Senior Member 2pot's Avatar
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    Why not take a valve to a metallurgist for investigation/testing?

    https://www.google.co.uk/url?sa=t&rc...OK01qcGTGCBC2t

  5. #165
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    Were the valve spring pressures all checked for spec? Did you check for coil bind? did you have the valve stems replaced or the valve seats recut?

  6. #166
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    Have reassembled the undamaged head today to check for coil bind but once assembled with buckets and cams I couldn't see enough or get a deeper gauge in to check. Paul Finch has said to use a dentist type mirror to get in and check. I'll try and find one and check.

    Springs were new at time of build so I would assume they'd be ok but I will check.

    Seats were original oem ones and were hand lapped. Guides were oem.
    No sign of uneven seat wear. (Sealing marks around the valve head are even) guides seem ok and there is no wear on the stems.

    I need to get pressures checked so I will find somewhere to do that for me.

  7. #167
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    Thanks to a tip from Paul Finch (thank you Paul) I have managed to check for coil bind and I think I've ruled it out.

    I measured the springs fitted into the head. Installed height with seat and retainer is 38mm.

    I then put the spring assembly (again with seat and retainer) into a vice and compressed the spring to 27mm (cams are 10.8mm lift). Although it looked tight I could compress the spring another 2-3mm after this point.

    Installed height (38mm).




    Simulated full cam lift 10.8mm




    So I'm assuming that rules out coil bind being the issue.

  8. #168
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    Maybe it failed cause of the extremely retarded timing that I see on the previous page, were you logging egt? Do you see any signs of burned valves? How much valve guide clearance is there, were the valve guides grinded in the ports?
    Last edited by Subzero; 1st November 2017 at 15:30.

  9. #169
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    There is zero sign of any heat related issues. No discolouration of valve heads or stems. There is also no sign of wear on any of the stems either. The inlet valves have been nitrided and show absolutely no sign of any wearing of the coating away so to me that rules out tight/worn guides.
    When fitting the valves and indeed on strip down the valves moved in the guides very smoothly.

    The valve guides haven't been touched. I never ported the heads so the guides are as they were with the factory valves.


    I don't monitor EGT but have never had any heat related issues. Not sure if this gives an indication or not but my Wideband sensor sits very close to the turbo and lasted close to two years and 20,000 miles which I believe is a good life for a wideband sensor on a car of this power. I thought they didn't last long if EGT's were high? Apologies if that seems daft but its the only indication I have that EGTs were not a problem.

  10. #170
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    is there a recommended spring pressure for the valves?

    Are they double valve springs?

  11. #171
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    Supertech double valve springs that came as a set with seats and retainers.

    Springs are 82Lb which is their fast road/race offering. They do a stronger spring but that's for drag applications only.

    According to the email from Supertech I had last week the springs I have should be more than fine for the use the car gets and the power level it's at.
    Last edited by daz-davies; 2nd November 2017 at 09:47.

  12. #172
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    So what is the spring pressure as installed in your heads ?

    Are the valve seats original ? Who cut the seats ? Asking as the valve seat markings seem pretty damn wide.
    speed didnt kill me, but taxation probably will

  13. #173
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    Valve seats are OEM just hand lapped with the good old fashioned sucker stick and two grades of paste.


    Unlapped on the left, lapped on the right.


  14. #174
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    Did you measure the valvespring install height when installing? 82LB is only at a certain install height.

  15. #175
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    I have the install height but no way of measuring the tension at specific heights yet.
    Will sort that at some point.

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