The explanation from the examiner is why he thought they failed.
They failed #1 because there was only 1-1/2 threads left to go before the adjusting cup bottomed out and because of the way the threads are cut on it, at that point was expanding the aluminum in the tip of the rocker enough to begin a stress riser.
The tensile strength of a stainless steel arm is much greater. Probably enough to have prevented the stress riser from starting. This is a strength of materials class. That's all.
Were all of the rocker adjuster cups set at the same height including the ones that didn't break?
You have hydraulic lifters. The plus/minus on the centering the plunger on them is more then a couple of threads on the adjuster. They are not all going to be exactly the same.
You use the shaft/rockers to eliminate the need for guides. The bearing assembly in the arm eliminates sway. What slop in the assembly? The arms? Again the arms are the only thing that failed.
When he is talking about excessive accelleration, he is talking about the rate at which the valve is opening because of the rate of angle of the lifter lobe. This is a roller lifter cam. What is unusual about that? That's the benefit of a roller lifter. It can open and close faster then a standard lifter cam.
Does that cause oscillation? I guess.
It didn't last? It lasted plus or minus what any race valve train would.
Should it be in a street engine expected to last 100,000 miles? AH HAH. Inspector Cleseau says NO, NO. NO, I have solvead the crime!
Kato? Kato? Where are you, you swine?
