Hi guys, a little question.
I bought new valve guides for the M20 recently. And as we all know the exhaust guide is a bit "drilled in" so to speak a the top for about 10 mm.
What is the idea behind this ?
Wouldn't it be better to use a guide (like an inlet guide) that goes all the way ?
Do 16H's have the same ?

My guess is that it's there to prevent valve stem to guide seizure as the upper end of the stem is exposed to exhaust gasses and thus expansion.