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Thread: balance shaft v/6

  1. #1
    Fuel Injected!
    Join Date
    Sep 2012
    washington indiana

    balance shaft v/6

    hi, put a rebuilt 4.3 in my truck with a mercruiser cam it don't have a balance shaft, the engine I replaced had a balance shaft. I always had a lot of knock counts with the old engine when you would get to a even speed 2000 or so rpms. old engine had a lot of miles on it250- 325.000 I just supposed it was worn out is why it had so much knock counts. I took the heads of and part of the knocks was the bearings on the balance shaft I think, and the rest abnoromal counts I think was the timming gears not worn out but worn. the engine I put in gets 3 knocks on start up an 1-3 more when shifting gears that is with 6-8 degrezz more timming. I put a rebuilt starter on it when I installed it an it started going bad an tuner pro would show 46 knocks at start up. I replaced the starter 3 knocks like clock work now on a start up. it surprised me tp was picking up the starter knocking. still tunning on it never tuned an engine with a cam. I have run as high as 12dgrezz more timming with out any more knocks but you could tell it was to much timming, knock sensor works with the engine running lightly tap the heads or block it picks up knocks , if any one with a v6 balance shaft engine has a lot of abnormal knocks at a steady cruise and reducing timming don't affect it it is proble the balance shaft or timming gears even if they are not worn out . more later about spark plugs if the change works. my engine is stock outside of the motor boat cam, sometimes it sounds and runs like a motor boat.

  2. #2
    Fuel Injected!
    Join Date
    Jan 2013
    I deleted the balance shaft from my 3800sc,it's pretty common when you reach or build to a certain power level.
    No real biggie,balance shaft is for 3rd order harmonics or what we call NVH.
    Other than a slight vibration usually at idle it shouldn't cause any ill effects.
    Mine had a slight vibration at idle,as soon as you went off-idle it dissappeared completely.
    It does register random multiple misfires at idle because of it,but deleting P0300 solved that.
    Never saw any detrimental effects to the timing I remember.

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