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JACKNOB

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About JACKNOB

  • Rank
    Member

Profile Information

  • Gender
    Male
  • Interests
    Auto racing, engine development and design/testing, fluid dynamics (computational & experimental) as applied to performance engines and total engine systems . . . etc., etc.

Profile Fields

  • From
    USA
  • Porsche Club
    Other
  • Present cars
    1966 VW
  • Former cars
    Numerous Ford based hot rods, numerous Porsche street and race cars.
  1. Yes. I remember well a very costly law suit P lost concerning this very subject. I contributed technical data, so to say, to the plaintiff. We have gone to the trouble of making CAD models of the late heads (liquid cooled) for determining various geometry since P is not so helpful. We do heads for high end domestic race teams and for virtually any question, I have several direct phone numbers to engineers at GM special projects. Thank you much, Jacknob
  2. Thanks for the reply. The reason for my need to know the allowable installed distance from the spring pad on the head to the tip of the valve is to maintain proper function of the hydraulic lash mechanism in the rocker. We know what the Factory ships new replacement heads at. I am trying to discern what the allowable variance from the OE dimension can be. I know this info is not published by the maker. Very poor oversight or intentional pitfall I do not know. After re-cutting used valve seats the valve will sit lower in the combustion chamber and equally higher at the spring end. How high is is the limit? I realize there is a shorter adjuster for helping this situation. (Refer to 15 59 04 in shop manual). A few decades past I could have called an old friend at the factory and he would have given me about any info of this sort. We live in a new world now and P has joined the effort to quash the aftermarket. Cheers, Jack
  3. Greetings, I am looking for someone who can help me with a dimension spec on 993 heads/valves. Specifically, valve stem height measured from spring pad to stem tip. There is a finite (max/minimum) dimension for this distance that must be maintained to allow the hyd. lash adjusters to function properly. I cannot find this simple spec anywhere. No one I know (and I know a large number of men in this game) has the answer or can direct me to a source. Jack
  4. Hello gents, Can someone decipher the following two sentences from the 993 Shop Manual: 993 shop manual: "4. Bore inner valve guide dia. to a dimension of "g" = 8.00 to 8.015 mm using a broach or precision boring equipment. In an emergency, the valve guides may also be machined with a special reamer." Please read the two lines carefully. I asked this question on another p-car forum and the guys were totally confused in their reply posts. I do this work for a living for about 45+ years. I need one of these 993 (8mm) guide broach systems now. I will go into detail of why this broach system is superior for guide bore sizing if I get some reply posts of interest. ---
  5. Hello folks- I am new here and am not sure this is the proper forum for the topic at hand. Anyway here is the question: Does anyone know anything about rebuilding (valve job) the 4.5L V-8 direct injection cylinder heads? I believe the vehicle is a 2007 MY. Any technical information or thoughts would be appreciated. Jacknob
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