If you want performance then you know you have to get as much air into the cylinder as possible. The bigger the valves the more this is possible. The standard 1275 mini and Sprite motor has only 1.3" intake valves, the standard Cooper "S" has 1.41" intake valves. This Special Big Intake valve is 1.464". This is a competition quality heat treated valve to eradicate wear problems from unleaded petrol that will work long and hard on any road or race car. Our race valves are produced in EN214N steel, stellite tipped and use the later narrow collet groove and current valve head shapes.