On my third set..splitting them..one or two ..change out whole sets.first it was loose adjusters.sloppy .RPM drops at idle 100..to 150 rpm....when they split.It's like a lousy spark plug.:finga: but it could become some big back firing if they snap...think I'll put the roller rockers on now.haha..Just abusing old 273 rockers for something to do. Roller cam..600 inch lift...hope it helps some one.