Broken Rocker Arm

Discussion in 'Engine Topic' started by connorbe, Sep 3, 2017.

  1. Lowend

    Lowend Administrator. .a car, a man, a maraca. Staff Member Lifetime Gold Member

    14,144
    173
    Mar 25, 1999
    San Jose, CA, USA
    I'll agree - could just be a bad rocker arm - it happens.

    Personally, I'd replace the whole set. There are a lot of cheap-crap roller rockers out there. If one went bad, I'd be looking at the others as time-bombs.

    My favorite rockers are the Comp Cam's Pro-Magnums
    http://www.compcams.com/information/products/rockerarms/promagnum.asp
    PN 1301-16
    3/8" stud, 1.52 ratio
     
  2. connorbe

    connorbe New Member

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    Jul 5, 2017
    South Dakota
    I'm actually not sure about the cam or compression ratio, I bought the car fairly recently and the PO didn't give me that information. I believe it's a mild cam, aluminum heads, . I messaged the PO asking about the heads and how old they were but he just told me that he bought them used so it's a very gray area.

    I did a leak down test this weekend and everything looks good, so I'm feeling hopeful. I'll be visiting the machine shop that built the engine back in 2011 tomorrow to order some stainless roller rockers, new pushrods and new valve covers. I'll inquire about the specs you listed as well while I'm there.

    Thanks for all the input everyone, sorry I didn't get back sooner, long weekend and all! I'll keep this updated once I get the new rocker arms and pushrods installed to let y'all know if that was the only fix needed.
     
    GoldenOne7710 likes this.
  3. Lowend

    Lowend Administrator. .a car, a man, a maraca. Staff Member Lifetime Gold Member

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    Mar 25, 1999
    San Jose, CA, USA
    It's really easy to tell of the heads are aluminum. If they aren't painted and aren't shiny, they are iron.
    If a refrigerator magnet sticks to them, they aren't aluminum
     
  4. connorbe

    connorbe New Member

    21
    1
    Jul 5, 2017
    South Dakota
    Oh the heads are definitely aluminum, I'm just not sure about Cam specs, compression ratio or valve spring rate.
     
  5. Lowend

    Lowend Administrator. .a car, a man, a maraca. Staff Member Lifetime Gold Member

    14,144
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    Mar 25, 1999
    San Jose, CA, USA
    Can you get a manufacturer and part # on the heads (usually embossed on the front) it will tell us what valvetrain is on the heads (or at least was originally)
     
  6. connorbe

    connorbe New Member

    21
    1
    Jul 5, 2017
    South Dakota
    Just checked, there aren't any part #'s or a manufacturer on the heads. I was at my engine guy's shop today and he was saying that he orders in blank aluminum heads and then machines them to get everything 100% - and he did the heads on this engine so I'm guessing that's the reason...

    I got a set of Comp Cams Ultra Pro Magnums today that I'll be installing once my pushrod replacement arrives, also grabbed some fabricated valve covers while I was at it, I'll have this baby back on the road soon enough!
     
  7. connorbe

    connorbe New Member

    21
    1
    Jul 5, 2017
    South Dakota
    Quick update for y'all:

    Turns out the lifter for the broken rocker arm got it's retaining clip knocked out, and the innards went into the oil pan, so I have a replacement. Checked the lifter's bottom face and it's still oh so slightly curved, which my engine guy tells me means the cam lobe should be fine. I'll be installing everything this evening and doing an oil change, then hopefully starting her up and getting this new lifter broken in! Can't wait to have it drivable again...
     
  8. Damon

    Damon Veteran Member

    12,927
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    Nov 16, 2000
    Philly area
    When that retaining clip comes loose it means usually one of two things:

    1. Bad valve adjustment. Please note this failure includes having the rocker arm lock nut/poly-lock back off, clearances open up, and you just beat the snot out of the lifter until it pukes out the clip.

    2. Valve float. Far more destructive to the valvetrain than you might think, even if a valve never "kisses" a piston. Even more destructive if it does. Again, there are a lot of things that can masquerade as valve float, including broken valve springs, worn out valve springs, wrong valve springs, or rocker geometry that is just way out to lunch (wrong length pushrods).

    Whatever you think you've figured out, please realize that lifter didn't just die. It was murdered.
     
    dale68z likes this.
  9. connorbe

    connorbe New Member

    21
    1
    Jul 5, 2017
    South Dakota
    hahaha I love this. What I THINK happened is that when the rocker arm broke it caused the pushrod to beat the snot out of the lifter one way or another... I'd guess that it's the first scenario you laid out there, but my engine guru also said that it could have been because the PO used the stock stamped steel rocker arms with a mild cam and heavier springs, which may have just been too much stress. Now I have a set of comp cam ultra pro magnums on there so I don't think that'll be an issue anymore.

    At this point I've checked everything aside from looking at the actual piston itself, but I did do a leak down test which came out good, and the engine turns over great, no resistance on that cylinder. Had to wait on a replacement pushrod to arrive, which I got today, so I'll be finally getting everything installed tomorrow and hope to start her up, get the timing adjusted and then break in the new lifter.
     
  10. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

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    Nov 4, 2004
    Ringgold, GA
    The newer endoscope cameras that you connect to a smart phone or laptop are in the $40.00 range now. Might be a good idea to stick one in the spark plug hole and take a look at the piston, just for peace of mind.
     

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