You have to do some of your own thinking here Highlander. Stan said to check the valve movement and used some generic language to check the movement of the valves by asking you to see if the valves were moving up and down. Your response was, "The valves are horizontal not vertical.". Well of course they're vertical, it's a boxer motor. Stan is well aware of the engine configuration since he's built several motors. But he's also been wrenching on good ole American iron for almost all of his life. Those valves go up and down. He didn't phrase it properly but it means the same thing. So check if all of the vales are moving in and out instead of up and down. If any of the valves aren't moving in or out then you have a broken valve spring and that will cause problems.