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Rocker Arm Foot Off Edge of Cam Lobe

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    Rocker Arm Foot Off Edge of Cam Lobe

    First, this is actually regarding an M10 head, but given the similarities between the M10 and M20 heads, especially pertaining to my question, I posted here given all the knowledge and traffic present.

    Quick summary: M10 head with a billet 284* cam, HD rocker arms, brand new rocker shafts, brand new everything that goes into the head. I'm currently assembling this head and noticed that two of the rocker feet are hanging off the edge of the cam lobes. A few others are sitting right at the edge of the lobes. The cam and rocker shaft thrust plate is installed and not worn. All rocker arm locating clips are installed.

    I will include a few pictures for examination. I can't see running the head like this... I believe this would cause accelerated and uneven wear.

    Have other people run into this issue? Given that the rocker arms seem to be visually centered on the valve stems indicating that the rocker arm locations are correct, it seems that the cam is to blame. As though the lobes were cast in the wrong locations. But they're inconsistent in the degree and even the direction that they're wrong.

    Thoughts? Thanks!



    '89 BMW 325is Zinnoberrot / '88 VW Jetta GLI 16v Tornado Red / '89 VW Jetta GLI 16v Tornado Red / '89 VW GTI 16v Bright Blue Metallic / '91 BMW 325i Black / '91 BMW 325i Sport Black / '92 VW GTI 16v Black / '92 VW GTI 16v Montana Green / '01 Audi A4 Avant TQM Silver Metallic / '01 VW Jetta GLX VR6 Black

    #2
    Where did you get the rocker shafts? I ran into this issue with my M20 rebuild using new rocker shafts from IE. Do the rocker shafts have alignment slots in them like the M20 shafts? M20 uses clips to align the rockers with the alignment slots. For me the Intake side was spot on, but the exhaust side was off by like 3mm.

    Comment


      #3
      Originally posted by halesyeah View Post
      Where did you get the rocker shafts? I ran into this issue with my M20 rebuild using new rocker shafts from IE. Do the rocker shafts have alignment slots in them like the M20 shafts? M20 uses clips to align the rockers with the alignment slots. For me the Intake side was spot on, but the exhaust side was off by like 3mm.
      Yes, shafts came from IE. The M10 has a single groove for a snap ring to locate the rocker instead of two slots like an M20 but same idea. What did you end up doing to solve the issue?
      '89 BMW 325is Zinnoberrot / '88 VW Jetta GLI 16v Tornado Red / '89 VW Jetta GLI 16v Tornado Red / '89 VW GTI 16v Bright Blue Metallic / '91 BMW 325i Black / '91 BMW 325i Sport Black / '92 VW GTI 16v Black / '92 VW GTI 16v Montana Green / '01 Audi A4 Avant TQM Silver Metallic / '01 VW Jetta GLX VR6 Black

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        #4
        I have had a bent rocker shaft pin that caused rockers to be off on one side- replacing pin moved the shaft into it's proper place and all was well.
        1990 Brilliantrot 325iS Build Thread
        1989 Zinnoberrot M3 Build Thread

        Comment


          #5
          Originally posted by AWDBOB View Post
          I have had a bent rocker shaft pin that caused rockers to be off on one side- replacing pin moved the shaft into it's proper place and all was well.
          Thanks, do you mean the rocker shaft retaining clip (K shaped part)? In this case, though it’s both intake and exhaust rockers that are poorly positioned on the cam and the retaining clip (slightly different design on M10) is not bent.
          '89 BMW 325is Zinnoberrot / '88 VW Jetta GLI 16v Tornado Red / '89 VW Jetta GLI 16v Tornado Red / '89 VW GTI 16v Bright Blue Metallic / '91 BMW 325i Black / '91 BMW 325i Sport Black / '92 VW GTI 16v Black / '92 VW GTI 16v Montana Green / '01 Audi A4 Avant TQM Silver Metallic / '01 VW Jetta GLX VR6 Black

          Comment


            #6
            Originally posted by Cinnabar325is View Post

            Thanks, do you mean the rocker shaft retaining clip (K shaped part)? In this case, though it’s both intake and exhaust rockers that are poorly positioned on the cam and the retaining clip (slightly different design on M10) is not bent.
            Yep, that's what I was referring to. Sounds like that's not the issue then, in your case, but figured it was worth mentioning!
            1990 Brilliantrot 325iS Build Thread
            1989 Zinnoberrot M3 Build Thread

            Comment


              #7
              Originally posted by Cinnabar325is View Post

              Yes, shafts came from IE. The M10 has a single groove for a snap ring to locate the rocker instead of two slots like an M20 but same idea. What did you end up doing to solve the issue?
              I ended up just re-using my oem shafts. That's how I figured out what the problem was. I lined the IE ones up to the oem ones and the slots on the exhaust side orientation were just way off. They sent me a replacement and it was the same way. I ended up pulling the intake side shaft out(I thought that one was fine) and it was the same way on the exhaust orientation.

              OEM BMW ones new are only $35 https://www.ecstuning.com/b-genuine-...t/11330634105/

              Comment


                #8
                You mean the pad is misaligned with the cam. '
                An older, also common problem was that the pad wasn't the right shape, and
                the edge of it contacted the cam, with disasterous results.
                Honestly, that would work, but it's not right.

                Are only 2 of the 4 off? I'd chuck that thing in the lathe, cut 2 new grooves in it,
                and then reverse the credit card charges.
                But then, I have a love- hate relationship with Ireland....

                t
                now, sometimes I just mess with people. It's more entertaining that way. george graves

                Comment


                  #9
                  Have you tried rockers from different positions? Those HD rockers used to have problems with the pads falling off. Wouldn't be surprised if a few of them weren't straight or if the pad were offset.
                  -Chris

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