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 air starting valves fire first because expanding compressed air drastically chills nearby metal and intake air, whereas non-air-admission cylinders maintain normal thermal compression temperatures favorable to immediate fuel ignition.