Why do we take the time to hone and properly size valve guides in Mamo Motorsports heads when some builders just test to see if the valves move freely after machining, and then assemble it? Too little clearance, there won’t be enough room for proper oil retention around the valve, which could lead to more friction, galling and wear, or seize a valve in the guide leading to severe engine damage. Too much clearance, the valve can move around in the guide and over time create an