Hey guys I am new to the site and have a question. I have a 355 sbc, Howards solid roller cam 246/246 dur at .050 and 582/582 lift, 186 double hump heads, double springs, roller rockers. I have less than 20 miles on the motor and have already broken 2 rocker studs on 2 different valves. They are breaking right at the bottom of the poly locks. I rolled the motor and it doesn't look like the rockers are hitting or even coming close. After looking at all the rockers though it looks like the poly lock hex has been hitting the rockers on the valve side. I have ordered a set of stud girdles as per some advice. Will this help the problem or should I look some where else? I don't know what size rockers it has, it has stock length push rods, if that helps.  

i hope that you have screw in studs... pulling broken off press in studs can be a real pain...  dont try it without proper hardened threaded tools. along with cutting new threads all the way to the bottom of the stud... a single nut even a grade 8 one will not have enough grip to pull the stud... you need over 5/8' of an inch of hardened thread contact to pull it...


oh.... and a long time ago... long long time... someone else complained of a simular problem...  he has the polylocks on unsidedown... hex down instead of the machined end...        

one last thing... some rockers use smaller diameter shank polylocks than others...

be sure that you change all you studs unless you can verify that this is an isolated problem...    grind  a notch in them so they cannot be reused and cause a failure later...    you might also want to rotate the shaft  to verify that the needle bearings did not brinnell the races... leave little dents in the races or flatten the needles...   it might have even damaged the rocker arms them selfs... streaching the bearing bore...you  might really take a dial caliper and measure the height from the bottom to the top of the rocker to see if it has streached any.. it might show up..?????  

I'd also check to make sure that you're not overlifting the rocker. If the rockers you have don't have enough travel to accomodate your cam, you'll break rocker studs pretty quick.

What make/model rockers are you using?  

I ditto Phil on the rocker travel.Are they good quality studs?