This VERY critical measurement is many times overlooked even by experienced mechanics. Valve to piston clearance is also defined both by depth into the valve pocket and radial clearance around the outside edge as well. Common depth clearance should be .080 for the intakes and .100 for the exhaust. Radial clearance which is the distance from the outside edge of the valve to the outside edge of the valve pocket should be at a minimum .050. While we would like every one of our cylinder and piston kits to be an absolute plug and play this cannot always be achieved with the many different cam, cylinder head, and valve diameter versions available in today’s market place. It is also of note that these distances can not be determined by rolling the engine through. They absolutely positively have to be physically confirmed by either clay in the valve pocket or by using appropriate dial micrometers. The Trock valve travel tool is absolutely wonderful and is available for sale on our website. If these depths and distances are not confirmed prior to start-up severe damage will occur and the components will not be warranted in any fashion.