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Thread: rocker failure

  1. #1
    Join Date
    Jul 2008
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    florida
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    256

    Default rocker failure



    LOOK CLOSELY he OBVIOUSLY had the clearances wrong, look at the inner area where the rocker stud adjustment nut has worn a a significant polished area where it was badly miss aligned, now proform may not be nearly (TOP OF THE LINE) but looking at the evidences strongly suggests a clearance issue or geometry issue with the valve train was a major factor in the rocker failure. I see guys knock the parts manufacturers all the time and at times its valid, but many times when parts fail its improper installation, or lack of knowledge as to proper procedures or how to check clearances or geometry.

    btw heres a better rocker design

    http://www.youtube.com/watch?v=UrWK73ysF3Y

    http://forum.grumpysperformance.com/...php?f=52&t=181

    http://forum.grumpysperformance.com/...hp?f=52&t=2746

    http://forum.grumpysperformance.com/...php?f=52&t=689

    http://forum.grumpysperformance.com/...php?f=52&t=196
    Last edited by grumpyvette; 03-08-2010 at 08:42 AM.

  2. #2
    Join Date
    Jul 2008
    Location
    San Antonio, TX
    Posts
    1,950

    Default

    As always... good info Grump

    Double and triple checking the valvetrain set-up is the best way to ensure durability. You can have failures with top-notch parts if it isn't properly set up. The extra time spent here is well worth it in the end. I've seen high-performance springs fail because they weren't set at the proper install height. For a set of single springs, this can cause a lot more collateral damage to an engine.... not pretty at all. I've also seen pushrods get bent because of improper installation.

    Kind of like spending a few extra bucks to balance the rotating assembly. Also well worth it even on a daily driver.
    http://www.crossedflags.com/forum/signaturepics/sigpic4_1.gif
    2001 Dark Bowling Green Metallic Coupe - 6-spd and mods (400 rwhp)
    2005 Aqua Blur SSR - 6-spd & LS2(Donna's hotrod), bone stock for now

  3. #3
    Join Date
    Jul 2008
    Location
    florida
    Posts
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    Default

    thats obviously not normal wear,issue and it takes a huge amount of force to pressure shear the valve tip,in that short time,

    Id bet you you find its a CLEARANCE issue, that type of damage usually indicates valve train binding, if your binding the valve train,pressure are immense, and parts fail rapidly, the most common on big blocks is the rocker slot binding on the rocker stud or spring bind or retainer to valve guide issues ESPECIALLY if the cam has more than about a .530 lift and your still using stock valve springs and rockers
    but check the piston to valve clearance, verify the installed spring height,(you could have to many valve seat shims) and if you adjusted the pre-load or lash on the valves COLD ID strongly suggest AFTER VERIFYING CLEARANCES that you adjust the valves AT IDLE



    read thru the links

    http://forum.grumpysperformance.com/...php?f=52&t=181

    http://forum.grumpysperformance.com/...php?f=52&t=282

    http://forum.grumpysperformance.com/...s+spring#p1818

    like Ive stated, many times youll need to verify ALL clearances, and the rocker stud to rocker slot clearance and the rocker polylocks to rocker body are usually overlooked
    retainer to valve guide and retainer to rocker, coil bind and measuring the installed height are all required, its very common for some shops to just throw on valve springs without measuring the installed spring height and just reinstall seat shims., you can NEVER just assume your average machine shops done everything correctly...you need to verify, thats why you need a basic understanding of what your looking at and a few tools










    [color:red]be very sure you check all the valve train clearances, having a rocker bind on a rocker stud can easily result in busted rockers or studs or bent pushrods[/color]


    it should be obvious that the slot clearance in some rockers , especially with poly locks significantly limits rocker movement before clearances become an issue


    BEEHIVE SPRINGS and FORGED STEEL ROCKERS GIVE A GOOD DEAL MORE ROCKER TO RETAINER CLEARANCE

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