[6pack] GP2 cam idle characteristics

[Sally or Dick Taylor]

Vance wrtes:

 From: Navarrette, Vance

     Dick, Robert:

     The valve lash setting specified by the cam manufacturer is
specified with a specific rocker ratio in mind. The "valve lash" setting
is in actualit
   The exact sizing of the lash depends on the CAM, not the valves
or rockers.

This is because there is a built in ramp on the cam lobe
designed to gently take up the lash before accelerating the valve off of
its seat. The amount of lash is therefore specified to correctly
accommodate the needs of the CAM LOBE. When the manufacturer specifies
the lash AT THE VALVE, he DIVIDES that number by the ROCKER RATIO to
determine the lash at the cam lobe. Ergo, if you change the rocker
ratio, you must change the lash setting AT THE VALVE to insure that the
lash setting AT THE LOBE remains correct....

Vance---I agree that the lash should be set to the cam grinders specs, for
most of the reasons you said. I don't recall a cam grinder asking what my
rocker ratio was before a cam was made and delivered to me. (Maybe they looked
it up)?
That's why I questioned the need to change the lash because of the rr.

Dick

On Thu, 19 Jun 2008, Sally or Dick Taylor wrote:

> Vance---Why would "higher ratio rockers" require more lash?

Dick