Broken rocker stud...

coolblue65 · Jun 24, 2006

Today was a bad day...

I was adjusting the rockers this afternoon, going pretty smooth, had the driver side done, then I moved to the passenger side so far so good; all of a sudden I heard a loud bang, some crazy popping noises, and oil shooting out of the driver side of my engine 10 feet (literally) across my garage. Fortunately, my friend was sitting in the car and turned off the engine immediately.

When I go to look to assess the damage, I see a rocker stud sheared in half. The broken piece was laying on top of the heads by another spring, and the rocker was missing....found it underneath the car. It doesnt look like there are any little pieces anywhere-it sheared off pretty clean.

I am assuming this is some kind of freak thing, I have never heard of this happening, anyone else? Or what could have caused this?

Any thoughts on how I should proceed? - I figure I will order a new set of ARP studs and just replace all of them.

All I want is to drive my car and everytime I think I can something else goes wrong!!!

pabear89 · Jun 24, 2006

Check to make sure your studs are centered.
I changed out to a slightly higher lift cam and broke one after setting the rockers.
Seems that there was one that had been broken before and replaced but about 1/8 off center.
With the higher lift cam it caused the rocker to bind at the stud at its pivot point with enough pressure to make the stud flex till it broke.

I used a small grinder to open the rockers pivot hole slightly to make it work.

PB

thehueypilot · Jun 25, 2006

I had a new one break in two driving down the road after about 2500 miles. Comp cams called it a cold forging double fold issue. They explained that once in a while the forging operation will grab two end pieces and slam them togather creating a two piece stud which will break under load at any moment. They did send me a free replacement stud. If they are old it might be time to replace them all just for better peice of mind.

XXBULLETSXX · Jun 25, 2006

Sorry to hear about your loss. I had a similar situation myself.

If it were me I would pull the heads and have a machine shop put in 7/16 studs and ensure they're straight. I certainly wouldn't be doing any machine work to your heads while their on my block. Call me chicken but I don't like the idea of one stray metal shaving going some where it shouldn't.

Think of it as a good opportunity to get some roller rockers and nice screw in studs!

Red Barchetta · Jun 25, 2006

I had a 7/16" ARP rocker stud break on me once. It sheered the top 3/8" of the stud off. My best guess as to what happened was that I didn't lock the rocker arm properly after adjusting it and the nut slowly started to back off. Once it got to the point where there was a gap between the push rod and the rocker arm, the pushrod just pounded the crap out of the rocker until something broke, in this case, it was the stud. The rocker (Comp Cams aluminum full roller) appeared to be fine. The pushrod was slightly bent, so I replaced the rocker stud and all the pushrods and made damn sure I locked the rocker nut properly and didn't have any more problems.

Where did the stud break? I'm curious if something similar happened to you.

10secgoal · Jun 25, 2006

Depends on a few things. I had a buddy with the same problem. The first time we thought it was a freak thing, no big deal. The second time we checked the rocker geometry. WAY off. Put a little black paint on the tip of the valve stem and rotate the motor. Make sure the paint removed is in the center of the valve stem.

D.Hearne · Jun 26, 2006

XXBULLETSXX said:
Sorry to hear about your loss. I had a similar situation myself.

If it were me I would pull the heads and have a machine shop put in 7/16 studs and ensure they're straight. I certainly wouldn't be doing any machine work to your heads while their on my block. Call me chicken but I don't like the idea of one stray metal shaving going some where it shouldn't.

Think of it as a good opportunity to get some roller rockers and nice screw in studs!

Read his signature, he's already got screw in studs. TF heads don't come without em.

Broken rocker stud...

coolblue65

pabear89

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thehueypilot

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XXBULLETSXX

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Red Barchetta

10secgoal

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D.Hearne

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