It’s actually almost comical that people are arguing over this.
5/16 is not that same as 8mm.
I can hear the conversation now.......
“I ran out of 5/16” guides for your head, so I used 8mm instead.
Yeh, there’s an extra .0025 clearance....... but I read on the internet that 5/16 and 8mm are interchangeable, and I didn’t bother fitting the guides to the valves because you don’t have a race motor”.
