"Best" performance... for your needs and driving habits.
One place to find is the end of the lash ramp, you do this by loosing the lash untill you hear some ticking. That is the point where the lash is big enough to miss the slow lift rate of the lash ramp, the lifter "flys over" and hits the flank of the cam lobe and that action makes the "tick" sound.
.002 or so tighter, from the point of "ticking" is the "upper end" of the lash range you have to work with. ( the widest lash setting)
This clearance number can be different for intake & exhaust on dual pattern cams.
For new engines, it is best to find this place on the cam lobe and start / break-in the new engine with looser lash settings.
Once you have the new engine somewhat "settled-in"... try some tighter lash settings and see if you like the results.
DD
