When, if ever, should I look for a PCV valve in Mercruiser engines? Does fuel injection have anything to do with whether or not a pvc valve will be utilized? If I understand correctly most carburated GM motors use breather tubes for crankcase ventilation vs pcv valve, is this correct? I was just thinking that I haven't come across any that had one...or so I thought anyways and was just wondering when and where I should be looking for one. Thanks.