I apologize in advance if this is a silly question but I couldn't find a clear answer anywhere else. I wanted to put a b18a1 valve cover onto a b20b engine. I am aware that non vtec B series valve covers bolt on to each engine with no issue, but I had read somewhere that they changed the pcv system from the black box to vent the crank case from the earlier engines, to having them vent through the valve covers on the later b18s and b20s. Would putting the older b18a1 valve cover onto a b20 have any negative effects since each engine had different crankcase venting measures? Or would it be totally fine

 

You could drill a hole in the A1 valve cover, insert a grommet that fits the PCV valve, and run just like the B20 valve cover. If you are going to leave the B20 essentially stock, I have seen many people run the PCV valve to open atmosphere (with a small filter clamped to it).

One could also essentially create an external "Oil Separator Box" without the large drain back hole in the block. This would be like a breather can that is sealed and the PCV valve would be mounted in the top.