I was wondering if there is any machanism preventing a camshaft against turning during service. It may happen that, when you turn off your engine, the camshaft stops in a position where lobe opens a valve. Then a tension from spring occurs between rocker and camshaft. When you unscrew a tensioner, a timing chain becomes loose.
What prevents camshaft from being turned by the rocker, especially in 2v engine, where the second lobe doesn't push the other rocker in the same time and can't stop the possible movement.
I was looking for some kind of blockade near camshaft or the rockers.
What I've found was this small mechanism:
But I couldn't find any information about it's function and I can't imagine how it works.