In a message dated 8/30/00 11:46:07 PM Eastern Daylight Time,
derekdrew@rcn.com writes:

<< When rocker arms are properly designed to not wipe against the
 >  valve stem (such as ours are) there is never a need for a roller tip. >>

Even the stock adjusting screws wear the tips out and have side loading of
the valve. This wear is not immediate but over time new adjusting screws are
needed as they wear out.

With the slider style you need to have a hardened tip cap to keep it from
wearing.

With the swivel tips the tip and adjusting screw wear is greatly diminished.

The roller style further reduces tip wear.

Robert