Wow, I replaced my valve cover gaskets and intake O rings because I was having problems with oil getting into my spark plug and causing a miss fire. However, the right side head has a whole that looks like it goes down into the crankcase and interestingly is by the plug getting the oil. The other end of the head has a similar hole but there is a cap in it kind of like a freeze plug. Can anyone tell me if my head should have a plug in both ends of it and if so where do I get one to plug the oil from splashing onto my spark plug. I have a Jaguar S Type with a 3.0 L engine. Thanks