If you have oil spitting out of the breather your catchcan is not working. This image
shows the basic requirements for an effective catchcan...
The arrangements of the inlet and outlet can be changed. The outlet can either be
piped to the intake vacuum or vented to atmosphere but the basic design needs to
contain all of these elements..
1. The entry can be from the side or the top but it must turn downwards (if from the
side) and discharge about 3/4's of the way down the can. Incoming fumes expand and
make a U-turn allowing oil droplets to fall to the bottom of the can. Collected oil
should not be allowed to submerge the end of the inlet tube.
2. There must be a mesh layer with a large surface area for the finer oil particles to
condense on and drain back to the bottom of the can. A packing of coarse stainless
steel "pot scourer" type material is ideal, and you can have a deeper layer than shown
in the diagram for greater collection efficiency. Just make sure the filter has a low
resistance to flow i.e. held under a tap the water easily flows thru the layer.
3. The outlet tube should be raised above the top of the packing to prevent condensed
oil being being "vacuumed" off the top of the packing.
So long as the inlet to your existing can is directed away from the outlet, you can
probably get away with packing a few stainless scourers (the ones that look like they
are made of turnings from a lathe) into the bottom of the can. Your engine should not
be producing massive blowby
Cheers... jondee86