<VV> Roller-tipped rockers

[BobHelt at aol.com]

There are basically two types of roller valve rockers. The first type  
retains the ball and socket of the stock rockers but places a roller at the tip  to 
contact the valve stem. This is the rocker I am referencing. The second type  
of rocker has a fixed type of pivot using needle bearings. This rocker is not  
being discussed.
 
A noted author (Graham Hansen) of a popular book called, High  Performance 
Chevy  Small-Block Cams and Valvetrains, flatly states  that when this type of 
rocker is used with hydraulic cams and lifters, the  roller DOES NOT ROLL  but 
slides across the tip of the valve stem, just as  the stock rockers do.
 
Does anybody have any information or data to either support this claim or  
refute it?
 
Thanks in advance,
Bob Helt
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