No that isn't an 18mm. I am going to try and use the hose off of my compression tester by taking out the valve stem. As soon as I find my stem remover I'm hoping it's removable. If not I'm going to need to order a kit off of Ebay. As for the lifter galley question, I have no idea. This engine was built by someone who raced cars and built many motors so hopefully they had this taken care of.