[6pack] GP2 cam idle characteristics

[Navarrette, Vance]

 	Dick:

	I presume they don't ask because they assume your RR is stock.
Course if your motor uses hydraulic tappets, then this does not apply.
But for the TR6 with its solid lifter cam, you would need to adjust the
lash setting if the RR changes from stock.
	I suppose someone could point to a cam where there is enough
margin that it doesn't matter, but the rule is correct; changing the RR
means adjusting the lash spec.
	Ask me how I know.....

	Vance


    Vance Navarrette
    Cogito Ergo Zoom
    I think, therefore I go fast

-----Original Message-----
From: 6pack-bounces+vance.navarrette=intel.com at autox.team.net
[mailto:6pack-bounces+vance.navarrette=intel.com at autox.team.net] On
Behalf Of Sally or Dick Taylor
Sent: Friday, June 20, 2008 12:43 PM
To: 6pack at autox.team.net
Subject: Re: [6pack] GP2 cam idle characteristics

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