8mm vs 5/16" valve stem

Hughes has 8mm, but not 5/16". They said 8mm and 5/16" are interchangeable. Really?

Hughes has 8mm, but not 5/16". They said 8mm and 5/16" are interchangeable. Really?
2.5 thousands clearance difference on a valve to valve guide measurement is a big deal. Guide needs to be sized properly for the valve stem. Guides and stems need to be measured sized properly to give adequate clearance period. As to Hughes you would think they would have learned their lesson with the first round of EQ's they sold that seized valves.