[fiveohpatrol]

0 lash is the point where there is no gap between the rocker/pushrod/lifter arrangement.
There are a couple different opinions on "where" exactly it is. Some say that you tighten down the rocker while spinning the corresponding pushrod between 2 fingers, and feel for when it just starts to get some resistance. Others say to move the pushrod up and down while tightening until there is no more movement.
Me, I kinda do a little bit of both, and it always works for me.

good luck

-Drew