I've been racing E30 325is cars for 4 seasons, and just recently broke a rocker arm for the first time. Nice clean break, and no other damage to the new motor. In fact, I was able to change it with out pulling the head. The rocker shaft slides right thru the cam gear. I have two questions. Is this common on the M20? The rocker certainly appears to be the weak spot. Does anyone have and tips or trick to advusting the valves?