Need ideas for review - Found damaged rockers and pushrods

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Need ideas for review - Found damaged rockers and pushrods

Post  CDicus on September 12th 2013, 1:11 pm

This is a first time for posting so bare w/ me.
Just got this car, ran it at the track 3 passes and didn't really notice anything with the motor at the time.
Fixed several items with the car and was ready to take to the track. Last item was to review the valve lash.
Pulled the passenger cover and only had to adjust 2 rockers. Went to the driver side, pulled cover and saw some very bad news. Saw several specs of metal lying in head. Went to check rockers, found 2 on the #6 cyl loose. Looked for pushrods, found them lying loose, beside the rockers. After disassembling the T&D rockers, I found what the damaged metal pieces were. The valve lash cap was missing from the exhaust valve stem. I will try to include several pictures. I just ran a leak down test and the cylinder shows about 12%  leak down rate, which should be good for a conventional ringed cylinder filed for nitrous. So, I am assuming no piston damage. After you look at the rocker and push rod damage, reply with suggestions. I am thinking the exhaust valve touched the piston and carried over to the intake. (Tried the browser and located my pics, but the browser says my pics are too big to load???) Oh well. The exhaust rocker has a flattened spot at the pushrod cup end of the rocker that rolls right over into the aluminum section of the rocker. A friend thinks the cup end was extending out too far where the push rod meets the rocker and this lead to the failure. I found the cup end up inside the rocker, so this could not be the case. The valve tip for the exhaust is beat up some, but I tried a lash cap on it and it fits well. The only other damage besides the rockers is the push rods will definitley have to be replaced. The tip that fits up into the rocker is beat to hell. I will probably go ahead and pull the head in the next few days anyway. Need to check for valve marking on piston top.
If you have ideas please send.
Thanks,
CDicus.

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Re: Need ideas for review - Found damaged rockers and pushrods

Post  460Dave on September 12th 2013, 1:35 pm

The next place I would look for evidence is the lifter and cam. There are any number of things that might have started your destruction, but you have to narrow it down by eliminating everything else in the valvetrain combo. Make sure the cam and lifters are still good on that cylinder. If the cylinder still holds pressure (leakdown test), then you probably haven't hit a valve on the piston. That would more than likely have bent the valve and wouldn't seat.

Take all the other push rods out and verify no others are bent.

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Re: Need ideas for review - Found damaged rockers and pushrods

Post  cool40 on September 12th 2013, 2:20 pm

Check the springs! Weak spring will let the valvetrain go crazy and knock that lash cap off,then you get what you have.Suspect 
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Re: Need ideas for review - Found damaged rockers and pushrods

Post  Lem Evans on September 12th 2013, 2:47 pm

cool40 wrote:Check the springs! Weak spring will let the valvetrain go crazy and knock that lash cap off,then you get what you have.Suspect 
Yep, or the valve hung open for some reason.

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Re: Need ideas for review - Found damaged rockers and pushrods

Post  70FB on October 21st 2013, 9:07 am

update???
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Re: Need ideas for review - Found damaged rockers and pushrods

Post  rmcomprandy on October 21st 2013, 10:45 am

I will presume you have a solid valve train; (not hydraulics).

The ONLY ways for the lash caps to come off the valve tips is to FLOAT the valves, for a valve to stick in the guide; (not totally but, temporarily) or for the caps themselves to disintegrate.

Pushrod to rocker arm geometry is of utmost importance to having a healthy valve train.

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Re: Need ideas for review - Found damaged rockers and pushrods

Post  Frenchie on October 21st 2013, 3:21 pm

Another option is the failure of the rocker body and the lash adjuster pulled the threads out (Adjuster pushed inside the rocker) You then create a "big" gap and can loose the lash. Happened to us this year when the aluminum rockers fatigued in the lash adjuster area and pulled the threads out. Now that is with big valve springs #1300+ open pressure. We lost lash cap and broke tip of valve and sent valve down in chamber causing major damages.

How old were your rockers?

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Re: Need ideas for review - Found damaged rockers and pushrods

Post  Dave C. on October 21st 2013, 5:12 pm

Was oil making it to the rockers? When we started my engine it wasn't oiling the rockers at all . We had to notch the lifters.

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