Harmonic Balancer Blues!!!

Engine, Trans & Driveline

  1. Longknife

    Longknife Well-Known Member

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    First question,,,, I have a 2468130 block (383) with 5-25-71 build date. stock bore, mildly built. Four speed. I always seemed to have a vibration in it. My thoughts came to light yesterday when the Harmonic balance came apart and began rubbing against the timing cover. I removed the balancer and it is a cast crank balancer. I also discovered that my engine has a cast crank,,, I actually scoped up through the drain plug to verify this. More research indicated that Mopar did put cast cranks in 2 barrel 383s' in 71-72. The part number for the balancer is 3577180. A two year only item. The 400 cast cranks used a different number. I have not had much luck in finding one on the net....

    Second Question, This 383 two barrel engine was undoubtedly first equipped with an automatic trans. I now have a four speed behind it. Would the flywheel have to be balanced with the engine? Did the flywheel out of balance cause the balancer to come apart? I know For a fact that the balance was OK when I got the engine. The cast number on the f-wheel is 8015,,,,, Thanks, Ed
     
  2. Don Frelier

    Don Frelier FBBO Gold Member FBBO Gold Member

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    Sounds like the balancer has been bad for a while.
    Put a new balancer on it and see how it acts then go from there.
     
  3. Charger Dana

    Charger Dana Well-Known Member

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    Someone would probably give you a forged crank. Certainly not expensive. But more expensive than a balancer.
     
  4. IQ52

    IQ52 Well-Known Member

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    The cast crank 383's and 400's use the same flywheel and torque converter offset balance. This leads me to believe that the 383 and 400 damper should interchange (though I have not been able to verify this). The flywheel must be balance to the cast crank 383. Below is how the old Direct Connection book shows how to balance a flywheel for the 383, 400 & 440 cast crank engines The same flywheel offset is used for all three engines. The drawing is showing the engine side of the flywheel.

    flywheel balance 002.JPG
     
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    • 69Bee

      69Bee FBBO Gold Member FBBO Gold Member

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      1) Use a neutral balancer and flywheel and re-balance the engine
      2) Balance the flywheel (per above), then look forever for the correct balancer. (Damper Doctor in CommieFornia can rebuild it for you)
      3) Get a steel crank, neutral balancer and flywheel, and still balance the rotating assy.
       
    • Plybeep68

      Plybeep68 Active Member

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    • 69Bee

      69Bee FBBO Gold Member FBBO Gold Member

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    • Plybeep68

      Plybeep68 Active Member

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    • 69Bee

      69Bee FBBO Gold Member FBBO Gold Member

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    • Longknife

      Longknife Well-Known Member

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      Thanks guys, Here is what I "think"? The HB for the 71-72 cast cranks 383's had the one offset pulley bolt hole. In 73 when the 400's came out the holes were then drilled equal and a new part number was required.???? SOOOO same balancer on either cast crank engine,,,,,
      I can not see the three drilled balance spots in the flywheel, so I'm betting that is my problem. I need to remove my flywheel and drill those spots. ORRR get the correct flywheel, Brewers offers the flywheel neutral or balanced (drilled)

      Brewer's Performance - Mopar A833 4-Speed Transmission and Component Specialists
       
      Last edited: Jan 15, 2021 at 10:08 AM
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