Quote:
Originally Posted by dude99
If all was normal the clearance wouldn't change. I believe these have some sort of device that rotates the valves as the move doesn't it? To promote even wear?
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In a perfect world, they should prevent uneven wear. But nothing will stop the wear on the valves and seats which leads to the tighter clearances.
The valve rotators (rotocaps) at the bottom of the spring align the spring forces to parallel with the valve stem and are designed to spin so the wear is even.
Valve guides wear regardless of this.
Over time, it seems that particles settle in the recess where the rotator rests and prevent the balls from rolling freely. Once the valve guides are worn, the rotocaps are less effective.