piston to valve .080 is fine.060 from in side of the retainer to top of valve seal and if your set up is lets say 1.750 and coil bind is 1.060 and the cam is .550 lift then before coil bind you would have 0.140 this is good you do not want to run the spring to far down this will brake down the spring. i like to stay at .100 before coil bind or more if the over the nose is good for the cam