I always kinda liked this one of a motorcycle engine with one end cut off. You can see how the valves work, and how they are designed to rotate under load, to

I always kinda liked this one of a motorcycle engine with one end cut off. You can see how the valves work, and how they are designed to rotate under load, to even out the valve seat wear. https://www.youtube.com/watch?v=c8hqoE1_7bA https://www.youtube.com/watch?v=c8hqoE1_7bA