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Thread: Scary Random Engine Clank/Tap

  1. #31
    Member #226 R Gruppe Life Member #147
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    Check the resistance in the plug wires, from the terminal inside the cap to the end of the plug connector. If compression is good and plugs, fuel injection, if u still have CIS would be next.

  2. #32
    member #1515
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    Did you check your cam timing after the tensioner upgrade?
    David

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

  3. #33
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    Quote Originally Posted by gled49 View Post
    Check the resistance in the plug wires, from the terminal inside the cap to the end of the plug connector. If compression is good and plugs, fuel injection, if u still have CIS would be next.
    Will do. I couldn't get it to stay running long enough to get a spark to jump to the engine, so I taped the plug so it was 1mm from shroud and set up iPhone video camera and saw good spark when I tried to turn it over. I can't get the dang compression tester fitting that I have in the spark plug hole - it's too deep. But I am starting to think maybe its a clogged injectors. I have to keep foot on gas to keep it alive even though its horribly rough running one-sided. It won't go over 3k rpm, except very occasional brief moments of shooting immediately up to 5k with no change in throttle position (pressed far in). And when I pull the 123 plugs they are super sooty carbon dusted rich wet- I saw that someone posted that a clogged injector made it not mist properly and that had same wet soot. Also saw tons of dust bits on the clean side of air filter chamber. Between the varnish gas and that dust sand i could see clogged injector as possible.
    Member #3896
    1973.5 911 T
    1974 911
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  4. #34
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    Quote Originally Posted by RSTarga View Post
    Did you check your cam timing after the tensioner upgrade?

    I did not because I was so sure that I could not possibly have let the chain hop a tooth. The fact that it's 123 does point to that, but I thought that it couldn't be that if I have had brief moments of good running.Seem right? If I strike out after cleaning injectors that will be next.
    Member #3896
    1973.5 911 T
    1974 911
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  5. #35
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    So it was not clogged injector that is making 123 misfire, And spray patterns looked ok, Name:  IMG_1193.jpg
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    Member #3896
    1973.5 911 T
    1974 911
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  6. #36
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    This may be my misfire problem on 123?

    I should have known to look for this right off. Had same problem on CB750 I brought back from the dead. Name:  IMG_1208.jpg
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    Member #3896
    1973.5 911 T
    1974 911
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  7. #37
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    Quote Originally Posted by RSTarga View Post
    Did you check your cam timing after the tensioner upgrade?
    I did not because I was so sure that I could not have slipped a tooth on cam sprocket, but must have jumped the intermed gear. So you nailed it. Thanks! I get .10mm valve lift on cyl 1 when the crank is at 30 BDC. Since there are 24 teeth on int shaft gear each tooth is 15 degrees so for extra credit I must have hopped two teeth. Sound right? I saw another 2 people have managed to slip the chain back a couple teeth on int gear with a plastic tool to slide between chain and int gear teeth and potential fiddling through sump hole per John Walker. Sound reasonable? Thanks
    Member #3896
    1973.5 911 T
    1974 911
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  8. #38
    Member #226 R Gruppe Life Member #147
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    I’m not sure how you check cam timing, but I’d go back to basics and reset timing by factory method with cam nuts removed.

  9. #39
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    Quote Originally Posted by gled49 View Post
    I’m not sure how you check cam timing, but I’d go back to basics and reset timing by factory method with cam nuts removed.
    Just ordered the p202 and p203 tools to do that. thanks
    Member #3896
    1973.5 911 T
    1974 911
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