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Timing questions

Discussion in '308/328' started by jdamon, Jan 25, 2017.

  1. jdamon

    jdamon Formula Junior

    Jul 6, 2015
    288
    Boston
    Full Name:
    Jeff
    Hello all, hoping to get some education on valve timing for my 83' 308 QV. I am currently in the beginning stages of a major, I have taken most of the peripheral stuff off. Before starting to take the car apart, it was running well in my opinion, no apparent timing issues, idled wonderfully, ran super smooth. My next move is to make some additional marks on the cam pulleys to aid in making sure everything gets put back together the same as it came out. When the flywheel is at TDC (PM1-4), all the cam marks line up perfect except for one, the intake cam on the rear bank. It is only off by a very small amount (I will post a picture). My question is, why this might be? Does this mean that someone adjusted that cam slightly? I am assuming the pulley can not move over time as the key is still present (and that would be catastrophic) but am questioning whether I should try to correct the position? Or, if I need to enlist a pro. I am very confident I can get it back together the same way it is now by making some strategic marks and ensuring no movement of the crank etc. but I felt I should at least ask the experts what may be going on here. Thanks in advance for your help!
     
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  3. jdamon

    jdamon Formula Junior

    Jul 6, 2015
    288
    Boston
    Full Name:
    Jeff
  4. jdamon

    jdamon Formula Junior

    Jul 6, 2015
    288
    Boston
    Full Name:
    Jeff
    This could also be "within spec", but the other cam marks are definitely more in the center of the mark placed on the journal. Thanks again for your input :)
     
  5. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    10,675
    San Carlos, CA
    Full Name:
    Mitchell Le
    Unless you put a degree wheel on the engine, there is no way to tell exactly how correct it is. Since it is running well for you now, and you are confident of being able to put it back exactly the same, you can just leave it alone. Although, you will never know how accurate that one cam is.
     
  6. mwr4440

    mwr4440 Four Time F1 World Champ
    Rossa Subscribed

    Jun 8, 2007
    43,778
    Bavaria, The 'Other' Germany
    Full Name:
    Mark W.R.
    A PRO here awhile back posted some picks that after degreeing the cams properly with a degreewheel and dial indicator, the marks were not even touching.

    Those are just 'assembly marks.' Little more.
     
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  8. jdamon

    jdamon Formula Junior

    Jul 6, 2015
    288
    Boston
    Full Name:
    Jeff
    Thanks guys!

    I did read through a few timing threads, but I didn't see the one showing the marks not lining up after correctly adjusting the timing. What I took away from the threads I did find, where there were a couple guys using the degree wheel, is that even when using the proper equipment, the "slack" in the belts was "more than 1.5 degrees", so one can only get it so close. Anyway, I just figured I would ask as I have the opportunity to re assemble. I am going to leave well enough alone, thank you!!
     
  9. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    10,675
    San Carlos, CA
    Full Name:
    Mitchell Le
    For a 348 and 355, I always do cam timing on all four cam shafts whether the marks line up or not when the engine is out. I have found that every car has at least one cam that is off by 2-3 degrees. I have seen cam timing assembly marks a little off, but not a lot off.

    For a 308-328, I have done the cam timing on my own car and the marks were dead nuts on. I don't make it a practice to do cam timing on other 308-328 especially if the car is running well. There is not a tremendous amount of power in those engines anyway.

    As to the slack in the belt, when you do enough of it, you will figure out how that works or not work. The spec is +/- 1 degree.
     
  10. johnk...

    johnk... F1 Veteran
    Owner

    Jun 11, 2004
    8,706
    New England/FL
    Once the engine is correctly time there is no reason to ever retime it unless the cam sprockets are removed from the cams and not remounted and dowel pinned in the same position. It's a simple fact of geometry. Belt length tolerances can affect timing by more that approximately +/- 1/2 degree.
     
  11. pad

    pad Formula 3

    Sep 30, 2004
    1,409
    Tequesta, FL
    Full Name:
    Paul Delatush
    After using a timing wheel with the engine out, I came up with the same results as you currently have. FWIW. To obtain better results, you will need to go to custom crank and cam wheels utilizing different cam belts. Check out Nick Forza's website.
     
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