Many things can cause the lifter to float , weak valve springs is one of them To many RPMs is another, especially in the burn out box The cam lobe design is a major factor in that also I just checked two of the valve springs on that motor, one of them has lost 20 lbs on the seat and more at max lift The customer did over rev the motor at the MATS race, he forgot to shift it into high gear on one run Lots of gremlins out there, many of them are man made As far as how deep on the grooves on those lobes I didn't measure or feel them, it has damages to one lobe from the flying motor pieces so I will send it in for repairs and ask them to regrind all the lobes so we can start fresh with a unblemished cam.