If you knw the cam lobe lift you can set the lash at zero and open the valve all the way by turning the cranksahft with a dial indicator on the retainer(make sure the dial indicator stem is on the same angle as the valve stem from left to right and front to back)and take the net valve lift and do the math. IE .400 lobe lift times 1.5 = .600, 1.6 times .400 = .640. Don't be suprised if the ratio are off some