<VV> Roller Tip Rockers

[Dale Dewald]

At 01:24 3/14/2009 -0400, Bob Helt wrote:

>  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.
>
>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?

It would seem that this would be something that could be (relatively) 
easily observed.  One could apply index marks of some kind to the edges of 
the rollers so that they could be observed with a high speed camera while 
the engine was running.  A set of half valve covers   could be used during 
the observation.

I  would expect that roller tip rockers would function as intended when new 
and continue to do so for some period of time.  At some point I can imagine 
that as wear accumulates, friction in the roller axle might exceed the 
sliding friction of the roller on the valve stem, then the roller action 
will cease.  At this point, the roller tip will function the same as a 
plain rocker.

It would be an interesting experiment to make these observations on a newly 
assembled engine, then again at 25k, 50k, etc miles.

Dale Dewald
Hancock, MI