valve lash

[Wojo]

I have this valve/pushrod noise in my in line six 1981 motor. Took off the valve cover, covered valves with plastic sheet to prevent oil from spilling all over the motor. Started the motor and was going to locate the noisy lifter....well, with all that noise I can not find it !
Tried to touch the valve to feel the vibration.......couldn't feel anything. Tried to tighten the #6 cylinder valves ( that's where the noise seems to be coming from) but that didn't help either.

How far can I turn the nut.........?

I will try to adjust valves by the book..see how that goes.

Another question:
the valve cover didn't have gasket, there was some sort of liquid gasket instead. I have new cork gasket to install, but there is a step in front of 1st cylinder ( about 1/16 in hight) I wander if that gasket will seal that.

Any comments welcomed.

Wojo