Some end play is good. It allows the camshaft room to
expand as it heats up. It also creates a little wiggle room
to reduce wear. However, too much end play can cause some
issues.
Cam Lobes
Too much end play can cause the cam lobes to wear much
faster than normal. The lifter should ride on the center of
the lobe. But as the camshaft moves, the lifter will ride on
one side of the lobe. This can cause uneven wear.
Distributor Gear
When the camshaft moves in the block, it can cause the
distributor gear to wear unevenly. It will also cause
ignition timing issues and a loss of performance.
Damage to Parts
If the camshaft moves too far, the side of the lobe could
come in contact with the lifter next to it. This can result
in damage to the camshaft, lifter, and possibly the engine
block.