Is this enough thread on rocker stud


I've had a rocker stud break on my engine for the second time (two separate ones). The heads have been on a bout a year and a half. Vortec heads, 1.5 RRs, upgraded springs, screw in studs/guidplates. The stud snapped in half at the lock. Is it beacause there is too much stress on the tip of the stud? Any ideas? experiences? Thanks
The pic is of the new stud. Thats how much thread coming out of the rocker arm. Is that normal. Sorry cell phone pics. I can better ones tommrow
How much lift? how much clearence do you have between the retainer and guide or valve seal? What type of lifters? and if they are hyd lifters how much are you preloading the plunger?
That looks like plenty of thread engagement.


