That link talks of a range from 40-60 thou being OK, where others talk of 20-60 thou...??? (RPI give 20-50) Also, can somebody explain how the rocker ratio is relevant to the pre-load? In my head the valve end of the rocker is being held on the valve stem by spring pressure inside the lifter, so there is no clearance anywhere in the chain of parts. Since the lifter spring is much weaker than the valve spring, its the one that compresses. If say there is a preload of 80 thou, we have some options (for the sake of argument) - shorten pushrod by 40 thou, OR, relieve the valve stem by 64thou (because that will lift the pushrod end by 40 thou, since the ratio is 1.6:1. If we pack the pedestal by 40 thou.....why will the pushrod end rise 64thou? The end on the valve stem is fixed as regards height, so that end is effectively the pivot point of the rocker if we move the pedestal.
Having trouble visualizing the movement at the rocker end.
Edit - just measured a rocker, and did the trig....40 thou at the pedestal moves the pushrod end very close to 1.6 ( I got 1.594)...lets just move on. based on my measurements (shaft centre to pushrod centre 22mm, centre to valve stem centre 37mm) the ratio is 1.68.