Added observation:
valves are suspost to rotate only on heads that use LEADED gas.  Helps keep the
buildup consistant around the seat so that you don't develop a high spot and
burn the valve.  UNLEADED heads are intended not to rotate the valves as there
is no build-up from the lead and in fact less lubrication to support valve
rotation.
Mark

Lawrence Dongilli wrote:

> > Another consideration, do these rockers rotate the valves as the stock
> ones
> > do?
>
> .....no,  not with the long linear contact area of the rocker pad and the
> zero offset between the pad and valve stem face.  He didn't seem to be too
> concerned about valve rotation because one of the things he preached was to
> grind the valve keepers so that the ends _did not_ touch each other when
> fully seated on the valve stem.  From the factory, the keepers touched at
> the ends, preventing them from achieving a 'vice grip' on the valve and
> allowing it to rotate from contact by the lateral offset of the rockers and
> adjusting screws.  This mod allowed the keepers to seat fully, forming sort
> of a 'wedgemate' with the valve stem, eliminating wear in the keeper
> grooves.  He felt that this was more important than maintaining valve
> rotation.  Besides, he felt that the valves would get an adequate amount of
> motion anyway from the small amount of winding/unwinding from the action of
> the spring.
>
> Regards,
>
> Lawrence Dongilli