How did this HAPPEN??

[GNDriven]

I was racing a fellow Buick guy when the engine started missing. The car would not rev over 2500rpm. I could hear a slight increase in valve train noise, so I pulled the driver side valve cover and found this. The rocker arm and pushrod are perfect. The pushrod is flat and not marked in anyway. What forces could have caused the stud to break? The rocker arm literally fell out as I lifted the valve cover.

 

[turbo nasty]

Check the rocker for freedom of movement. If the bearings are going they bind up will cause it to snap. There have been some issues with Scorpions bearings in the past.

Another possibility is overtightening the polylocks.

Though it is not uncommon for the studs to break where yours did.

Give Tom a call.

And retorque your heads:biggrin:

 

[disco stu]

Cheap chinese studs, that how. Had it happen on 2 cars. Upgrade to ARP's and you'll be fine. Replace them all, another will fail eventually.

 

[GNDriven]

I am calling Tom now.

A Mechanical Engineer who specialty is metal forensics, looked at it and described the waves of fatigue failure. Meaning it did not break clean with a single blow, yet fail over time (many cycles).

I am talking with Tom right now and he as agreed the ARPs are made from a better, more controlled material. He says normally the standard stud works fine, but has been known to break with a more aggressive cam profile.
Oh and the standard stud he uses are made in the USA.

I am going to replace all of them with ARPs. Thanks

p.s. Hows about you coming over and you re-torque the heads

p.s.s How is your transmission?

 

[V6RACER]

That looks like the #1 intake vavle... might want to check it to make sure it still slides freely.

 

[GNDriven]

Yep #1 Intake took a dirt nap. V6Racer do you mean compress the valve to verify it moves OK?

guess I can find a valve compressor somewhere.

Does anyone know what the ARP part number is for the rocker stud kit?

 

[V6RACER]

Yep #1 Intake took a dirt nap. V6Racer do you mean compress the valve to verify it moves OK?

I think I'd take the heads off and inspect them or at least the valve springs and make sure you haven't messed up any guides and check the valve heights.

 

[turbobitt]

Could be hydrogen embridlement failure. Common failure on poorly processed fasteners.

Allan G.