This document contains information about the main components of an automobile engine. It discusses the cylinder head, cylinder block, piston, connecting rod, crankshaft, camshaft and valves. The piston converts combustion pressure into rotational motion via the connecting rod and crankshaft. The cylinder head covers the cylinder block and contains intake and exhaust valves, spark plugs and other components. The document provides diagrams and descriptions of each key engine part and how they work together in the engine's operation.