Hemi valve failure

Anyone like to put forward a theory as to why this valve failed?

Some backgronnd:

Hemi Mopar/Edelbrock heads.
Comp Cams 925 springs,10 degree retainers, 10 degree locks and Hemi lash caps.
Comp 230/238 hyd roller cam and Comp hyd roller lifters.

The failure happened after about 2 1/2 hrs dyno run time. After removing the valve covers we found a lash cap had come out and the roller wheel was running on the collet.
At first we thought the lash caps had been bottoming out on the collet but after examaning other valves (which all have some degree of lock groove failure) we discovered that the lock groove was getting eaten away allowing the collet to ride up the valve stem and push up the lash cap.
We were lucky to catch this before a valve dropped!

Any help would be apreciated!

Tim

What kind of valve spring pressures are you using?

This type of failure occurs when the retainer is hitting the rocker or the locks are incorrect or lock location is high and possible even with the top of the stem and the rocker or the roller tip is hitting the lock.Anything that creats a movement between the lock and retainer will cause this type of failure.Also look for coil bind and retainer to guide clearences.Look for witness marks at the locks and retainer for movement and at the underside of the retainer and top of seal and guide.Don't rule out valve spring float either.

Ok,
Valve springs are 150 on the seat and 370 on the nose.
No coil bind, no lock to guide contact,no roller to lock contact!
Will check for rocker arm to retainer contact and cant be sure if valve float was an issue as it seemed to rev through to 6000 ok!

Since you say you have no coil bind -

What amount of travel do you have left after full lift to coil bind? I've seen springs with more then .100 have harmonic issues before.

Quote:

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Anyone like to put forward a theory as to why this valve failed?

Some backgronnd:

Hemi Mopar/Edelbrock heads.
Comp Cams 925 springs,10 degree retainers, 10 degree locks and Hemi lash caps.
Comp 230/238 hyd roller cam and Comp hyd roller lifters.

The failure happened after about 2 1/2 hrs dyno run time. After removing the valve covers we found a lash cap had come out and the roller wheel was running on the collet.
At first we thought the lash caps had been bottoming out on the collet but after examaning other valves (which all have some degree of lock groove failure) we discovered that the lock groove was getting eaten away allowing the collet to ride up the valve stem and push up the lash cap.
We were lucky to catch this before a valve dropped!

Any help would be apreciated!

Tim

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Odd thing, Maybe related maybe not. This weekend when they talked to about Capps explosion to Rahn Tobler he said there was a problem with the machining of the valve locks. Your's looks to be starting to out the same way.
Doug