eng rod balancing thread

Small Block Mopar Engine

  1. Rapid Robert

    Rapid Robert Well-Known Member

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    I have run across 2 procedures for rod balancing. (1) says to weigh the small ends & take off material from the small ends to get the small ends equal, then weigh the whole rod & take off material from the big ends till the total whole weights are the same. (2) another says to weigh the small ends & grind the small ends till the small ends are equal then weigh the big ends & take off material from the big ends till the big ends are equal. WHICH IS CORRECT? thank you for your time.
     
  2. yellow rose

    yellow rose Overnight Sensation FABO Gold Member

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    You do BOTH ends.
     
  3. Rapid Robert

    Rapid Robert Well-Known Member

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    so you equalize the small ends then equalize the big ends as in #2 & you ain't weighing the whole rod procedure like in #1
     
  4. yellow rose

    yellow rose Overnight Sensation FABO Gold Member

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    Yes. Some guys get all bent up about getting the center of balance on the rod correct but I’ve never seen anyone who actually builds this stuff get excited about it.
     
  5. Rapid Robert

    Rapid Robert Well-Known Member

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    got it, thank you brother!
     
  6. toolmanmike

    toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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    Find the lightest rod end and balance the rest to it. Switch ends and do the same. Do you have a fixture and scale? A narrow belt sander does a nice job.

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    • Rapid Robert

      Rapid Robert Well-Known Member

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      I should be good to go. appreciated. that looks like quality work
       
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      • 66fs

        66fs FABO Gold Member FABO Gold Member

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        You can weigh the whole rod to check your work. big end + small end = total weight
         
      • MOPAROFFICIAL

        MOPAROFFICIAL FABO Gold Member FABO Gold Member

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        Pretty rudimentary guys both ways are right because if you just equalize the small ends then obviously the big end would be where you would be removing material from to get the entire rod to then weigh the same as the next and next and next the next... "come on man" lol and the beam weight falls into both measurements.

        Its all in the wording.
         
      • yellow rose

        yellow rose Overnight Sensation FABO Gold Member

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        Yeah, I forgot to mention that once you get all the pin ends the same, and all the big ends the same you have to go back and check all the pin ends again.

        They change. Not by much, but they change and if you are already there, why not touch them up??
         
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        • pishta

          pishta I know I'm right....

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          There is a guy on YouTube who runs a reputable import axhine shop in Costa Mesa, ca. Lots of old Fiat stuff and the like. He marks and takes all the caps off and whitles them down the the lightest ones weight. Then he takes all the rest of the rods (little ends) and just weigh them outright and takes all the extra weight off the balance pad. He puts them all back together and they all weight the same. Im not sure if this technique is only for 180 degree crank 4 cylinders where both sides cancel each other out or if it also applies to V8 cranks because it sure is easier to do it this way than to hang balance a rod on a jig and get repeatable weights down to the gram. Its harder than it looks using consumer grade scales, but can be done very easily with just weighing each side if the rod straight up and down on the gram scale. Highly repeatable down to <1g on my cheap scale. I'd think that type of range is well within the manufacturers static balance requirements once you give that equalized rod, bearing and piston pack to your balancer.
           
        • circlepilot

          circlepilot FABO Gold Member FABO Gold Member

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          • Captainkirk

            Captainkirk Old School Mopar Warrior

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            You learn something every day here!
             
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            • TT5.9mag

              TT5.9mag Two atmospheres are better than one

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              Most important is how you measure the big end vs the small end. If you don’t have an accurate scale and a rod weighing fixture than it’s all for not.
               
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              • Rapid Robert

                Rapid Robert Well-Known Member

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                I was wondering about that myself. there's a utube vid on making the fixture (yes it needs to be perfect) & I was thinking of a HF scale, way back I had one & it was just as accurate as my buddys high dollar one.
                 
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