Breaking Rocker Studs

[kevpow]

I have an all steel LLM engine that was built new this year. Ive only got to run it a couple times but each time, i've broken rocker studs. I run Dart heads, roller cam and lifters with Crower roller rockers. The first time out, I broke two. I purchased a stud girdle set and installed. Ran the second race and just found another broken stud. What could be causing this. I havent over revved the engine, turning about 7600. Rocker ratios are 1.65/1.5. Any help or ideas will be very helpful. Thanks.

[istock11m]

Have you checked pushrod length? Could be the culprit. What brand of studs are you running?

[kevpow]

Rockers

I havent checked the pushrod length. I run ARP 7/16 screw in studs. I appreciate the suggestion!

[kevpow]

Rockers

Yes, breaking right below the poly locks. Im not sure of the ARP part #. Ill see if I can dig up my build sheet. The first time it broke # 4, 6 and 5. I replaced studs with new ARP and brand new stud girdle, this time it broke #2. I didnt even know it broke this time. Seemed to be running fine and strong at the end of the last race. Started getting ready to winterize and found it. Sound familiar??

[dirty white boy]

valve springs ant hitting coil bind are thay???

[fast_crew]

How far down on the studs are your rockers, are they down on the shank abit or mostly sitting on the threads? What are your spring pressures, possibly valve float? Also make sure your are using the Pro series studs.

[DaveBauerSS6]

A big time engine builder said if you tighten the poly lock allen and then turn the nut a little more it will twist/ crack the stud. This motor was brought to me for t-shooting 4 broken studs/ 2 nites. Put ARP studs in and the problem went away.

[runyou-2]

I'm gonna put my money on "coil bind"

[runyou-2]

A big time engine builder said if you tighten the poly lock allen and then turn the nut a little more it will twist/ crack the stud. This motor was brought to me for t-shooting 4 broken studs/ 2 nites. Put ARP studs in and the problem went away.

Not saying he's wrong,but that is exactly how i have always tightened mine for years.Never have broke a stud unless the rocker itself wasn't enlongated enough,or coil spring bind.When you start breaking one after another right away,the problem will show up quick.

[dirty white boy]

Not saying he's wrong,but that is exactly how i have always tightened mine for years.Never have broke a stud unless the rocker itself wasn't enlongated enough,or coil spring bind.When you start breaking one after another right away,the problem will show up quick.

bout only 2 things it could be...

[DaveBauerSS6]

Not saying he's wrong,but that is exactly how i have always tightened mine for years.Never have broke a stud unless the rocker itself wasn't enlongated enough,or coil spring bind.When you start breaking one after another right away,the problem will show up quick.

Ive always tightened it again for insurance.
The motor was dynoed and then it broke the first race. He couldn't explain why it broke the first time.

[andy16]

retainer to guide clearance too tight could also cause this if spring isn coil bound.