I took what was sold to me as a B18A1 head to a shop to have it pressure tested. The shop says everything checks out and they had it machined to make sure it was not warped. The guy told me the valves were not the correct size to be a B18 head. They said they were bigger than B18 valves. When I put it on the car a few weeks ago the oil and water mixed before I ever started it. Either way my question is..... Is it possible that it is a JDM head or that it might be a B20 head??? If so what head gasket would I use then. I will make sure of what it is before I leave the shop tomorrow. I compaired the 2 heads before swapping them and they looked the same to me with the exception of the valve cover.