Getting rid of air cleaner riser

[Ochre Ogre]

I don't like getting rid of stuff on my engine without knowing what it is (or it original function). I have new billet air cleaner I want to put on, and would like to get rid of this and just put a breather in the valve cover. What is the purpose for this, as the PVC is in the other valve cover so the crankcase is breathing. Picture was borrowed from another post as I'm at work and did not have a picture.
Thanks

[cooperhw]

As far as I know these were just so that any unburned fuel or oil type vapors could be harvested and run back through the motor. Kind of a second bite at the apple to reduce emissions.
Might be wrong though.?

[Bigdav160]

The PCV is pulling in crankcase vapors to burn them and that device is allowing clean filtered air to replace them.

You can eliminate it but it's still best to run a filter on that valve cover

[Davidf]

Without the device (assuming you plug the opening in the valve cover), you would be pulling a vacuum on the crankcase. On modern cars, this is required. On older cars, a vacuum on the crankcase would not be a good idea. The riser also helps the air cleaner clear obstacles...on my engine anyway.

[Ochre Ogre]

I was planning on adding a filtered breather, would this cause a vacuum? As far as clearance goes that should not be a problem, I already checked the air cleaner housing and it clears all linkage. If I have to I would just use a 1/2" spacer.