All,
I broke a rocker arm on track. It was original from the factory (about 205K). Kept it at the rev limiter too long in third gear. I had not adjusted the valves since I owned the car (about 10K hard miles). I caused the failure by my actions (and lack of action).
The crack occurred all at once. There were no fatigue beach marks on the broken pieces. The crack initiated from an irregular casting line on the bottom of the split fingers. The new style rockers with the extra material are definitely stronger, but the casting line is still there.
I have polished this one small area to smooth out the casting line, eliminating the stress riser it created. If there were one thing to be made officially legal, this polishing of just that one area would be it. It is simple, cost effective, and backed by solid engineering principle.
Also, I adjusted my valves per the Bentley manual. Larger gaps would cause the valves not to open as far (less air flow = less power?). Remember to replace the flat spotted eccentrics while you are in there.
I raced at Mid-Ohio with SCCA the week before you all (y’all) were at the NASA Nationals. The car ran great. No problems. Had a great time.
Carl Fuhrmann
#89 ITS
Indianapolis, IN