Pushrod to Roller Rocker geometry?

Engine, Trans & Driveline

  1. Steve009

    Steve009 FBBO Gold Member FBBO Gold Member

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    So this is my first time building a non-stockish engine. It’s a 400 to 470 stroker. Harland sharp roller rockers with a custom grind solid flat tappet cam. I’m trying to measure pushrod length to order a set and have never done this before. Read a bunch of articles and they mention push rod to adjuster screw geometry. From what I gather you want about 1.5 threads showing through the bottom of the rocker but the geometry is important. From the pics below can someone tell me if that angle is fine? No shims have been added here and I hope to not add any. Also, do I measure length while the feeler gauge is holding the correct lash? Final question, is cold lash cam specific or is there standard intake/exhaust lash that I should be using?

    thanks for the help. I’m sure to most of you this is common knowledge but it’s intimidating for a first timer.
    -Steve

    DFC8F7B1-49B5-460B-BDCF-6DC5564623C2.jpeg D494B666-AECD-486A-A489-9036667529FF.jpeg
     
  2. MoparLeo

    MoparLeo NRA BENEFACTOR LEVEL LIFE MEMBER FBBO Gold Member

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    Another consideration with the pushrods is that the push rod ends must be the correct shape to mate up the lifter pockets and rocker adjusters.
    I would check with whatever manufacturer that you pick for the custom pushrods, for their requirements for measuring the length.
    The lash will vary depending on the materials used as different metals expand at different rates when they are hot. Valve lash is generally adjusted when the engine is hot.
     
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    • 493 Mike

      493 Mike FBBO Gold Member FBBO Gold Member

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      But, after setting one set as close to perfect as you can, let the engine cool to ambient and remeasure the clearances. Then you have the cold spec. Proceed to set the other 14 and you can repeat this cold setting in the future.
      Mike
       
    • HEMI-ITIS

      HEMI-ITIS STREETER on LI FBBO Gold Member

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      Picture looks good,how is the witness mark on the valve stem??
       
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      • Steve009

        Steve009 FBBO Gold Member FBBO Gold Member

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        Haven’t turned the engine over yet to check. Wanted to verify that the geometry was good first. If you say that angle is ok I can move on and turn it over to see the witness mark. I have to also figure out the cold lash spec as well to set it up properly prior to checking the witness mark.
         
      • IQ52

        IQ52 Well-Known Member

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        Sigh.... Please bear in mind that with an aluminum head the cold lash will be some .005"-.006" tighter than the hot lash. And that if the adjusting screw is out 6 threads or zero threads the witness mark on the valve tip will be exactly the same. Or remove the push rod and hurl it across the garage and see if the roller tip contacts the the valve tip any differently.
         
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        • Steve009

          Steve009 FBBO Gold Member FBBO Gold Member

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          I’m not sure what you are getting at with the “hurl it across the garage” comment.
           
        • Mark Barnes

          Mark Barnes Well-Known Member

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          "

          I hate to prove that I'm dumber than I look, but wouldn't the cold lash be .005-.006 LOOSER...or did I misunderstand?
           
        • beanhead

          beanhead Well-Known Member

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          When things heat up the pedestals expand and move the shafts up away from the valve tips.
          Mine (aluminum heads/iron block) move exactly .006". So I must set my cold lash .006 tighter. .020 is what I want it to be hot, so I set it cold at .014...comes out on the money.
           
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          • Mark Barnes

            Mark Barnes Well-Known Member

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            Got it! Thanks for the explanation.
             
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            • IQ52

              IQ52 Well-Known Member

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              Perhaps you already know that changing the rocker arm adjusting screw thread length and the pushrod length, on a shaft mounted rocker system, will not make any difference on the roller tip to valve stem tip contact patch. Therefor even removing the pushrod entirely won't change the rocker roller to valve tip contact. You have to change the roller fulcrum to valve tip location to effect the valve tip contact patch. Maybe we don't even care. Sorry if I'm confusing the issue or wasting our time.
               
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              • steve340

                steve340 Well-Known Member

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                You should put a couple of light springs on the valves you are checking to avoid camshaft damage while you play around. Lube all the lobes with good stuff.
                For checking and cold setting try 4 thousands tighter setting and use this at all times during the checking process.
                The pushrod cup must be slightly lower than the oil hole in the back of the rocker arm so it gets oil splash. But don't have the adjuster way out of the rocker arm.
                As IQ52 has pointed out the rocker geometry will not be affected by the pushrod length but you can influence valve lift - bearing in mind that oil hole thing.
                If found Harland Sharp rocker to have poor rocker geometry.
                 
              • 493 Mike

                493 Mike FBBO Gold Member FBBO Gold Member

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                I concur about the HS geometry.
                Mike
                 
              • Steve009

                Steve009 FBBO Gold Member FBBO Gold Member

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                i did not know this. I always thought pushrod length is what changed the contact patch on the valve tip. As for the angle of the pushrod to the ball tip on the adjustment screw, is there anyway to know if the angle I have is ok?
                 
              • Steve009

                Steve009 FBBO Gold Member FBBO Gold Member

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                I’m stuck with these HS rockers now so have to use them even if the geometry isn’t ideal. The springs are very light so that shouldn’t be a problem when trying things out. That’s for the advice on the oiling. I heard usually about 1.5 threads showing us the right amount for the rocker adjustment screw but I’ll double check to make sure it’s slightly lower than the oil hole. So that angle I pointed out in the pictures seems to be fine?
                 
              • RemCharger

                RemCharger Well-Known Member

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                Imo,, yes.
                The only way to change the p/r to rocker angle is a different rocker....or move the lifter holes in the block.
                So it "is what it is".

                I guess the B3 relocation could change it slightly too.
                 
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                • steve340

                  steve340 Well-Known Member

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                  You would need to check the geometry first before deciding if you think it is good enough then decide the pushrod length to suit were the rockers/adjusters end up.
                  As others have said the only way to change the rocker geometry is the raise or lower the fulcrum point of the shafts. Dave Hughes rockers are far better than HS.
                  I lowered mine around 80 thousands and shifted the shafts towards the pushrod about 10 thousands. I machined the heads.
                  The angle of the adjuster is set by the manufacturer so you cannot adjust. You will find the valve will start to lift and the the pushrod top will start to sweep towards the intake.
                  You need to try and minimise this sweep - and pushrod length will help here.
                   
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                  • Wietse

                    Wietse Well-Known Member

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                    Check your sweep pattern first on the valve stem, if this is too wide or too far off to the side you will require to relocate the rocker shaft. (most of the time with roller rockers you need to raise and move away from the valves)
                    I used the B3 kit to set mine to center and minimal sweep, see pictures.

                    By doing so you alter the length of the push rod.
                    Pushrod length does not change any geometry, the length is determined after the geometry is set.
                    Go for an as long as possible push rod, depending on the way of oiling (through lifter or from rocker arm) you will need to ensure the oiling hole in the rocker arm can reach the cup, if the cup sits too high it might not get oil from the oiling hole. But in that case it would be a design flaw of the rocker arm as it will force you to have multiple adjuster threads below the rocker arm.

                    If your push rod would be "short" you need to increase the length of the adjuster below the rocker arm, by doing so you will increase the "side way" motion of the push rod which will make you loose valve lift and puts a bigger angle between the adjuster and push rod which increases the side load on the ball/cup.

                    IMG_4193.jpg IMG_4194.jpg
                     
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                    • 493 Mike

                      493 Mike FBBO Gold Member FBBO Gold Member

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                      Who makes the "B3" kit? Thanks.
                      Mike
                       
                    • hunt2elk

                      hunt2elk FBBO Gold Member FBBO Gold Member

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                      Mike at B3 Racing. He just joined our site a couple of months ago. He is a very knowledgable and helpful guy. Some very good reading in his tech tab on his website.
                      http://www.b3racingengines.com/
                       
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