PCV's and Breathers? Some questions

Hi,
unmetered air...sort of. Its regulated by the valve itself and is a mixture of blowby and air.
Look at the common stock set ups. The breather in in the air cleaner housing. This is considered a closed system cause its in the air cleaner housing, but its still out side air.
If you had the wrong PCV valve then that might pose a problem. Vince

what 1965pony said. the pcv valve is what controls the airflow. 2 breathers would work if you closed the vacuum port, but there really is no reason to do that. if u only had a pcv and no breather on the other side, where would the pcv valve get its air. it would try and suck oil into the intake. you cant just have a pcv valve. the newer cars 5.0's that only have an oil fill still pull crankcase vapors and still have a pcv, they just pull the fresh air out of the intake rubber tube and the pcv comes out of the back of the intake manifold instead of the valve covers. same effect.

Think of the PCV system as a circular flow system. The inlet is the breather and the outlet is the PCV to your intake. On an engine in decent shape, air is constantly flowing in a circular pattern.

Old engines with excessive blowby overwhelm this system and vent out both sides, but that is not the way it was designed to work. Keep it just like you have it.