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Thread: Is dowel pinning of 2.7 RS engine case necessary?

  1. #1

    Is dowel pinning of 2.7 RS engine case necessary?

    According to How to modify and rebuild your Porsche 911 engine, racing engines where more than 250 HP is anticipated should have dovel pinning to reduce flex. Some say that this modification should be made in any engine rebuild, also on engines with "normal" output. Any thoughts about this? I am having built a 2.7 RS clone engine for my 1973 911E targa. If dovel pinning is to be carried out, the case has to be shipped abroad, which will be fairly expensive.

    Einar Irgens
    Norway

  2. #2
    I'd have it align bored at a minimum. Dowel pinning isn't really necessary because producing 250 hp out of a standard compression 2.7 isn't likely.
    "Be who you are and say what you feel because those who mind don't matter and those who matter don't mind." - Dr. Seuss

    Early S Registry #235
    rgruppe #111

  3. #3
    I think honing the main bearing bores to std. is in order if the bearings are tight when torqueing the case. The bearing bore sometimes gets smaller rather than larger. Ive found this to be more of a problem with hot running 2.7 motors, not so much for 2.0-2.4 mag cases. Line boring and oversize bearings are expensive.

  4. #4
    Senior Member
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    The necessity of dowel pins or anti-shuffle pins is more related to RPM . I have seen 2.7's run at high RPM (5,500 ) with wear at the main bearing journal case half because of movement .
    Also more of a problem in the 2.7 because of the longer stroke .

  5. #5
    Thanks, all of you. Still not sure what I will do, though :-/

  6. #6
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    I'm pretty sure there is a machine shop in Europe that can shuffle pin a case, it isn't rocket science, just exact measuring. How are the bores now? Does it need a line hone too? Personally, I would shuffle pin the case if it is going to be enjoyed.

  7. #7
    It's a "while you're in there" sort of thing. No second chances if you change your mind.

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    "Be who you are and say what you feel because those who mind don't matter and those who matter don't mind." - Dr. Seuss

    Early S Registry #235
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  8. #8
    member #1515
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    and worth every penny for peace of mind
    David

    '73 S Targa #0830 2.7 MFI rebuilt to RS specs

  9. #9
    Senior Member majordad's Avatar
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    I did not have it done on my 2.4S restoration, the shop said no real need. After 2000 miles the engine tightened so we had to do it.

    Just do it !

  10. #10
    Quote Originally Posted by majordad View Post
    I did not have it done on my 2.4S restoration, the shop said no real need. After 2000 miles the engine tightened so we had to do it.

    Just do it !
    I will!

    The engine case seems to be in very good condition, so I concidered omitting any machining, but from what I am told, the magnesium no matter what will loose shape after years of shifting temperatures. Better to do i properly and avoid having to tear down the engine again prematurely.

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