alright, my M20 seems to be sounding like a 'diesel' and I was told to adjust the valves. I looked at the valve adjusting DIY and it says that when the valves are fully closed, I should be able to fit a .010 feeler gauge... well whats confusing me is, why would ANYTHING fit there? if the valve is closed, it should be a fully closed seal between the valve and the head?

I guess I need to open it and look at it to get a better idea.

Just wanted to ask this before I tackled this thing... the diesel noise is oh so very annoying. plus I'm sure I could get back a few HP back once they are adjusted.

is .010 right? I saw some people doing .010 intake, .012 exhaust here.