Personally I feel that you will see more of a change with changes to the valve timing events, rather than just lift itself. Using rocker arm ratio as an example, is the increase or decrease in lift making the power? Or is it the change of valve timing events and valve velocity showing the increase/decrease in power?
Billy Godbold has talked about a multiplication factor he uses for calculating valve lift.
He works on 0.45 - 0.48 of the intake valve. As an example 2.25" intake valve x 0.45 = 1.0125" of valve lift. On a Super Stock or Pro Stock style engine it sounds about right. You're probably not going to apply that factor to some of the engines we build.
