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Need math help (damper timing problems)

Discussion in 'The Garage' started by Blazer_Boy, Apr 4, 2002.

  1. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    I used an older block and crank (orange paint on block) in my rebuild with a newer damper and things are not timing up. I investigated a little further and may have a solution. Most of the Chevys we have have the timing mark back 10 degrees behind the keyway. I believe my my crank used the older 2 degree behind the keyway setup and as a result won't work with the timing marks. I need to an accurate way to make a mark 8 degrees over.

    I got creative and remembered that pi (3.14) times the diameter of the damper (8") will give me my circumfrence. I then divide that by 360, multiplied by 8 and got .558". Am I on the right track here or not. I found TDC kinda by moving the motor by hand using an old dip stick in the hole for #1. The new mark is about double of .558", so a little over 1". I was timing it with the gun and things seemed where they should be now with that newer mark. Did I do something wrong here, can anyone tell me that a little over 1" is correct. .558" only gets me halfway there.
     
  2. JIM88K5

    JIM88K5 1/2 ton status

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    Depending on the condition of the rubber ring in the damper it may have shifted a little. Pro Form makes a good looking cover that bolts over the damper and has the timing marks on it. It looks kinda like a fluid damper. Make sure the damper and pointer are from the same application. Go to the local dealer and ask to see a damper and check the keyway vs. the mark.
    Jim
     
  3. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Oooh, been there already /forums/images/icons/crazy.gif. I had the top half of the shroud off along with the fan and pulleys having a look see. I put a couple old dampers up to it and its all in the same spot. I have pics of 2 and 10 degree versions in this parts interchange book and the difference between the marks looks alot more than 8 degrees. I wonder if they are going by 8 degrees out of 180 because the damper goes around twice in a complete cycle.
     
  4. FWP

    FWP CRS

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    Here's how I solved that problem on mine. When the heads were off the motor, I used a dial indicator and found exact #1 TDC. Then scribed the new damper at the old 0 degree mark on the timing cover. You can get close to TDC with the feeler method, but it wont be perfect. I use the vacuum gage method for setting timing, the timing mark is just a sanity check for myself..
     

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