blowby, how much is too much?

Blowby is combustion pressure getting into crtankcase by bad compression rings or bad exhaust vale guides. There is a certain unavoidble amount but lots is a sign of something worn out. Usually PCV takes carte of it either through a breatjer or a check. Valve tied into your intake. Some old carts would get so much pressure in the case that they would ooze oil from about every gaslet or even buckle the valley pan.