Diesel engine air start valve timing is controlled by（）

A.the air start valve timing gears and rods
B.a cylinder check valve
C.individual cams and valve gear
D.an air manifold poppet valve

A.degree of cylinder air turbulence
B.firing pressure in the engine
C.quality of fuel to be injected
D.duration of the ignition delay period

A.laying a straight edge across the crank webs at the crankpin and measuring the distance to the crankpin in two places
B.measuring the crank drop on either side of each crank throw while the crankshaft is slowly rotated through one revolution
C.rotating the crankshaft through one revolution, pausing each 90oof rotation to measure bearing clearances, top and bottom
D.taking micrometer reading between the crank cheeks opposite the crankpin every 90°of crank angle rotation