Hello, Allpar Forums member or visitor! If you were a member, you would not see this ad!

Register or log in at the top right of the page...

  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

400 big block harmonic balancer

Discussion in 'Performance' started by kzooman83, Sep 28, 2015.

  1. kzooman83

    kzooman83 Active Member

    Joined:
    Feb 6, 2005
    Messages:
    386
    Likes:
    10
    I recently verified true TDC against the TDC mark on my harmonic balancer and found the mark on the damper to be off by around 7 degrees (at the crank). This got me wondering if my balancer has slipped; now that I am paying attention, it does seem that there is a slight vibration at certain engine speeds, although it is not all that noticeable and I can't confirm that the damper is causing this. Could the 7 degree difference just be manufacturing tolerances, or should I suspect that the damper is junk?
     
  2. dana44

    Ad-Free Member

    Joined:
    Jun 17, 2002
    Messages:
    19,326
    Likes:
    1,238
    I would get another damper, I don't believe 7 degrees is factory tolerance. There are internal and external balancers, it should be cast into the front of the balancer if it is, saying something about external balance for cast cranks or something like that.
     
    pt006 likes this.
  3. kzooman83

    kzooman83 Active Member

    Joined:
    Feb 6, 2005
    Messages:
    386
    Likes:
    10
    That's what I needed to know. My 400 has the stock cast crank, the only affordable option I have found for an aftermarket damper is one from professional products that includes a couple different counterweights for different big block mopar applications. Given I live in the snow belt, it is almost impossible to find big block mopar parts at the junkyards around here also, since cars don't usually last that long here. Any idea what a good used one might go for online?
     
  4. pt006

    pt006 Active Member

    Joined:
    Dec 24, 2014
    Messages:
    1,284
    Likes:
    491
    Kazoom; finding TDC on a big block is a little tricky because of the plug angle. That said, I'd check the harmonic balancer rubber for softness. It should be hard and probably have little cracks in it. That's ok. If the rubber is soft [like oil soaked] don't use it. Be aware that some mopars had dual timing marks [one on the timing cover and another on the additional bracket that had a 1/4" round tube in it. I would paint a radial line across the rubber to see if it moves in the future.
     
  5. kzooman83

    kzooman83 Active Member

    Joined:
    Feb 6, 2005
    Messages:
    386
    Likes:
    10
    I hadn't thought of using a mark to see if it moves again, that is a good idea. When I found true TDC I marked it on the damper and I used that to time the engine; the engine likes that better than if I time it from the factory timing mark. I also have an aftermarket chrome timing cover, so I wonder if that could be part of the reason the original marks don't line up. If it has slipped some, it does not seem to be slipping more; I periodically check timing on the engine and the readings seem to be pretty constant.

    I just want to make absolutely sure that this damper is not having a problem because I know a failed damper can cause damage to the rotating assembly.
     

Share This Page

Loading...