[art leong]

I understood that the way they interpret the rules today. If the valve makes a notch in the piston, it would not be allowed.
Years ago with the hemi car we would put a worn out set of valve springs on the motor.
Do a few burnouts with the car. Then take the head off grind the valves, put the real springs on. And go racing, It made it hard to exchange heads, as the notches were head specific. That was when they checked for duration and overlap.