[Gaz64]

Cam lobe, base of lifter, lifter pushrod cup seat, pushrod (both ends), rocker arm (pivot and tips), top of valve stem, valve seats.

There are many little hammers bashing away in any engine with a solid valvetrain.

All those tiny clearances, are the reason for wear, and the need for periodic adjustment.

Hydraulic camshafts are ground differently to solid cams.

Solid cams have gentle quietening opening and closing ramps.

Ever heard how noisy a hydraulic cam is when converted to solid lifters?