Hey Del. I asked the OP for the cam ID and looked up the cam and it is a symmetrical intake-to-exhaust design. If you check out the open/close points, it works out to show a 4 degree advance. The whole point of this check is a quick check of cam timing to see if it is close to where it should be (4 degrees advance), or is 15 or 30 degrees off, indicating that a sprocket is off. It is not meant in this case to be a method to actually set cam timing exactly.