Abstract: A cylinder head in a cylinder head assembly includes an upper deck, a fire deck, gas exchange conduits, and a coolant cavity extending peripherally around the gas exchange conduits. The cylinder head also includes an igniter socket having an igniter post, and a radially outward sleeve step continuously circumferential of an igniter bore center axis. A cooling moat is formed between the igniter post and the sleeve step. The coolant cavity includes a valve bridge through-channel and a valve bridge part-way channel each fluidly connected to the igniter socket to provide coolant flow into and out of the cooling moat passively.

Abstract: A cylinder head casting in a cylinder head assembly includes a coolant cavity upper surface and a coolant cavity lower surface forming a coolant cavity. The coolant cavity lower surface is contoured to form an igniter-support prominence and cast-in coolant channels through the igniter-support prominence to feed a flow of coolant through a cooling moat extending circumferentially around an igniter post supporting an igniter sleeve. The igniter sleeve abuts the cylinder head, radially outward of the igniter post, at a first contact location and a second contact location in an alternating arrangement with a first coolant feed opening and a second coolant feed opening. Related methodology relating to making a cylinder head is also disclosed.

Abstract: A spark plug assembly is disclosed for use with an engine having a cylinder head at feast partially defining a combustion chamber. The spark plug assembly may have a spark plug at least partially disposed in the cylinder head and configured to generate a spark Inside the combustion chamber to ignite an air and fuel mixture. The spark plug assembly may also have an insert configured to receive the spark plug and at least partially form a cooling passage surrounding the spark plug.