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Carb adjustment

Discussion in '308/328' started by johnhunt, Mar 20, 2017.

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  1. jmaienza

    jmaienza Formula Junior

    Jan 8, 2009
    629
    Massachusetts
    Full Name:
    Joe
    #26 jmaienza, Mar 24, 2017
    As stated by others, each distributor must be checked, then calibrated on a special distributor machine. Once each distributor is calibrated (specs in owners manual), then each distributor must be matched with each other so they are both advancing at the same rate.

    Think of your engine as two, four cylinder engines working together. If one distributor is advancing improperly, it creates drag and your engine will not reach maximum potential.

    Unfortunately, the distributor machines are not common anymore and qualified technicians and parts (springs and shims) are also a concern.

    I'd suggest to clean them up and send them out. There is a lot to tuning these distributors and well as the adjustment and installation position of the points.

    Here is a link to a Marelli distributor specialist.

    Home
     
  2. johnhunt

    johnhunt Formula Junior

    Aug 9, 2013
    343
    Washington
    Full Name:
    John Hunt
    #27 johnhunt, Mar 24, 2017
    I will do a rough check with a stroboscope.

    I don't have the R2 points (for idle)
    With just R1 points should the idle be set at 7 advance (as I have read on the internets) or 16 advance as in the workshop manual?

    5000 rpm should be 34 +-2 per manual

    if both banks advance then that will have to do for me this year.
    -John
     
  3. johnhunt

    johnhunt Formula Junior

    Aug 9, 2013
    343
    Washington
    Full Name:
    John Hunt
    #28 johnhunt, Mar 25, 2017
    [​IMG]


    So my flywheel seems to have different markings than the workshop manual.

    Any idea what this mark is? I am guessing 7 degrees (well because it says 7*)

    The next mark pm 5-8

    There is no 16 degree mark but there is 34 degree.

    I'm a bit confused

    Thanks
    John



    Sent from my iPhone using Tapatalk
     
  4. johnhunt

    johnhunt Formula Junior

    Aug 9, 2013
    343
    Washington
    Full Name:
    John Hunt
    #29 johnhunt, Mar 25, 2017
    I tuned to to idle at that mark.
    It advances to 34 at about 4000 rpm (both sides).

    Idle was great for awhile. Solid 4 kg air. 950rpm.

    Then it went wonky and sucked more air 5 -7kg and basically slowed and died.

    I am surmising that I am losing a cylinder on the 5-8 bank.
    (1-4 and 5 would all fire the strobe / will test 6-8 in the morning )


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  5. johnhunt

    johnhunt Formula Junior

    Aug 9, 2013
    343
    Washington
    Full Name:
    John Hunt
    #30 johnhunt, Mar 29, 2017
    bump... help plz
     
  6. derekw

    derekw Formula 3

    Sep 7, 2010
    1,521
    London, UK
    Full Name:
    Derek W
    #31 derekw, Mar 29, 2017
    John,

    You know that your one distributor is bad (missing springs) and the other is probably also off so I suggest you fix those properly or send them out to be fixed first. I suspect that your one distributor (with one spring) is advancing too early and may be sticking due to the one weight being "loose." You can pick up dwell meters for a few bucks on ebay and a good timing light and well marked flywheel will help get the correct ignition curve on both distributors using different springs and shims.

    Your fast idle system may not be working correctly, try disconnecting it.
     
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