It's been years since I played around with small engines. My question is how much wiggle should there be with the valves on a side to side motion? I have spent most of my time playing with SBC motors and I know you should not compare apples to oranges. The engine is a 16HP Briggs opposed twin flat head and there are no removable valve guides. The valve stems are hardly worn and and measure almost like new. So the only possible play would be from the drilled holes in the aluminum block. Valve seats and the valves are in real nice shape, just don't know if the block is too worn or not.