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SR20 Camshaft Issue: Looking for some input

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  • SR20 Camshaft Issue: Looking for some input

    So I got all of my head stuff back today, and I noticed something I've missed when I took everything apart. On the #4 lobe of my exhaust cam, one edge seems to be slightly higher (.001"-.002" is the best I can measure atm) as if the rest of the lobe was worn down but not that edge maybe? These cams have at most 3k miles on them between two failed motor builds (sad I know). They haven't been run since I sent them out for WPC treatment and they were used for adjusting the lash between the rocker and cam by Port Flow Design.





    Here you can see that the rocker arm (if sitting in the middle) rides right on the edge. If you slide the rocker arm across the lobe, it does catch on the lip of the groove.


    I'm not sure if I should run the cam or not. Part of me thinks that if the rocker arm doesn't hit it, I should be fine. I'm mainly worried about rocker arm tilt. Any constructive input would be greatly appreciated!

    www.2LiterTurbo.com (Personal Site)
    96 240SX SE: Track Car | 90 Skyline GTR: Bucket List Car | 07 Legacy Spec B: The DD

  • #2
    The rocker wore that groove most likely. I'd just make sure it's not sitting across it and run it. Keep an eye on it for further wear, as it'll start going quicker with the harder surface worn away.
    '18 Chevrolet Volt - Electric fun hatch for DD duty!


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    • #3
      I had a little rocker tilt on this rocker in the past, so I'm sure that's what happened. That coupled with a few bad valve guides are what were causing my shims to go from before. These are 260/12mm lift Tomei Procams. I was thinking of going with a 270 exhaust cam, so that would solve any worries in the future (haven't decided if that's the best route for me yet though), but I'd like to get the motor running and finished breaking in soon. I took tomorrow off from work so I can install the head, lol.

      www.2LiterTurbo.com (Personal Site)
      96 240SX SE: Track Car | 90 Skyline GTR: Bucket List Car | 07 Legacy Spec B: The DD

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      • #4
        If you want to do it right and not have to worry about losing a rocker, then replace the cam and shim the head properly. Single sided lobe wear caused by initial incorrect shimming can cause the rocker to break usually ending in catastrophic engine damage, in fact, you’re more likely to break the rocker if you try re-shim it now for the very obvious fact that the cam lobe is now not perfectly horizontal.

        Are you sure the rocker is still ok? Usually with one sided wear the rocker takes a beating as well.

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