In a medium-speed marine propulsion engine equipped with direct admission air starting valves, the cylinders without air starting valves fire first because the __________.

Correct Answer: Option D — cylinders are not chilled by the expansion of the starting air

Cylinders lacking direct air starting valves fire first during startup because unvalved cylinders are not subjected to the chilling expansion effect of compressed air, allowing higher initial compression temperatures to readily ignite injected fuel.