Cylinder heads mount atop engine cylinder blocks, sealing combustion chambers and housing intake and exhaust valves. These cast aluminum or iron components feature precisely machined valve guides, seats, and ports to control gas flow. Integrated coolant passages regulate operating temperature, while camshafts or direct actuation systems manage valve timing. Cylinder heads typically incorporate spark plug threads or fuel injector mounts for the ignition or delivery of the air-fuel mixture. Proper sealing is achieved via a head gasket between the head and block, maintaining compression critical for engine performance.