As stated below the adjustment of the valve lash isn't indicative of cam wear. But it IS indicative of valve seat wear. Lots of threads showing on the adjuster screw means a) the head was thinner than stock or b) the valves have receeded into the head (or c- the valve has stretched). Watch the adjustment, especially on the exhaust. If you are always correctign tight exhaust valves it is time for rebuilt head.

I disagree a little bit with John on the crankcase ventilation and leaky crank seals.

A felt seal that has been sitting for a long time will harden up and leak terribly. A NEW seal or one that has been run regularly (in a not too dusty environment) works OK.

Crankcase ventilation is important. The "flame trap" may or may not have a "media" in there (like a scotch-brite pad) to help oil mist to condense and run back into the crankcase. It should. The suction of the manifold (mostly at idle) is of great assistance in preventing excess crankcase pressures and pumping losses. You should have a PCV valve in-line to restrict the flow of gasses into the manifold under high vaccum conditions. The oil filler cap also needs to be clean as that is where the air originates (less the blow-by).

Mike!