Any pictures of the broken parts? I agree that something has to be seriously wrong with that set up. I have run a ton more spring pressure than that on the common shafts with no issues many times in the past. I have never broken one of thier rockers. I bought a set of heads from someone(whole other story)that had T&D common shaft rockers that obviouosly were never cared for and chucked some pushrods and they still were not broken. A number of them had bad bearings afterward and were very beat up but they were still in one piece.