The Stovebolt Site Forums The Shop Area Engine Shop Road Draft Tube

I use K&N filters on my carbs, completely disconneted from the valve cover.
You can clean and reuse them. They are also more efficient than paper.
I also use a dedicated valve cover filter by K&N - The typical breathers stuffed with some foam are not very efficient.

Using the exhaust for crankcase evacuation is basically like a mini road draft inside the exhaust pipe after the collectors.
A small tube is welded inside the exhaust pipe with its important angled cut end facing away from the flow, just like the road draft tube.
The pressure difference at the cut angle sucks out the crankcase vapors. A regular check valve prevents exhaust gases from flowing back. A PCV valve is only needed to limit flow when used with manifold vacuum.

This system is more efficient at higher rpm and somewhat like the opposite of a PCV system which is most efficient at idle and cruising.