Crank case breather - PCV

[Phil Waterman]

Hi Svenn

There are two different types of PVC that I have encountered which I have reason to believe were original. Both of them are designed to be mounted vertical, there is no spring inside. Correct function is when you suck on the side toward the carb (top) and air comes through but when you try and blow back through it no air or very little passes through. In short a one way valve.

Early type was mounted over on the breather side of the engine while the later type is mounted over on the manifold side.

Arrow is the direction the air should flow or up in the normal mounting position. The none spring versions used on Chevy CMPs doesn't work if mounted other than vertical, some of the later PVC valves with springs don't really care which way is up.

Cheers Phil