This document contains diagrams and explanations of valve and port timing for various engine types. It begins by explaining what engine valve timing is and how the camshaft opens and closes the valves. It then provides diagrams and timing angles in degrees for: 1) A 4-stroke petrol engine valve timing diagram 2) A 4-stroke diesel engine valve timing diagram 3) Port timing diagrams for 2-stroke petrol and diesel engines along with their timing angles. It concludes by providing more details on the theoretical port timing diagram for a 2-stroke diesel engine.