It is basic but it can get confusing which is why I like to have all parts in front of me to measure and do the math. For example Ferrea doesn't know what a 5/16" stem is supposed to measure --every valve I ever got from them measured .308"-.3085" and that is not even close to 5/16". So if a guy never saw that before he would assume the aftermarket calls a .308" stem a 5/16" stem valve size. J.Rob
Thanks for this about Ferrea valves, I just ordered 4 replacment valves for a Magnum head with 5/16" stems that didn't fit. Measured valve stems installed at 0.308". Now I know where those valves came from.
