Hi Reubs, The valve clr is the rocker to valve setting not valve to piston. To check valve to piston clearance, Man it,s pretty involved.. Prob best off to google "checking valve to piston clearance",Just to make sure what I,ve said is correct I,ll give it my best shot anyway. With your bottom end fully assembled an camshaft installed in the position it will be used in, either advanced, retarded or heads up, [Thats what degreeing the camshaft in is about] place some plasticine or modeling clay on top of the piston lightly oil top of plasticine or clay so valve doesn,t stick to it when it touches.Place light valve springs in cyl you wish to check. {They must be able to shut valve & also be soft enough to be opened by finger pressure, Install head torqing it down to spec, now with the piston at top dead centre take valve height measurement with valve closed then open, there is your valve to piston clearance.Depending on the lift of your cam and the timing of it ,how much yr block is shaved, if yr head has been shaved, the height of yr head gasket, it all goes into the combination.Just don,t valve bounce it cause it all goes out the window then LOL!! When you got the cam did you say I want this cam or did you tell them about your motor an they offered this 1?? Forgot to check WIKI before I posted this whats the factory cam got for lift?