25.Camshafts are usually driven by timing gears or ___________.
26.The valve cam slope angle determines the _____________.
A.opening and closing points of the valve
B.opening and closing rate of the valve
C.height of valve opening
D.amount of time the valve remains open
27.The arrangement and shape of the cams on a diesel engine camshaft directly control which of the listed groups of operating conditions?
A.Speed, torque, and horsepower production
B.Firing order, valve timing, and valve lift
C.Fuel consumption, efficiency, and cylinder pressure
D.Scavenge pressure, compression ratio, and exhaust pressure
28.Carbon deposits building up, in, and around the injection nozzle tip are least likely to occur when using which of the listed types of fuel injector nozzles?
29.A port-and-helix fuel injection pump having upper and lower plunger helixes is designed to _____________.
A.vary fuel delivery and return pressure
B.vary the beginning and ending of injection
C.operate with residual fuels only
D.provide maximum fuel delivery rate
30.Which of the following statements describes a fuel injection pump marked “timed for port closing”?
A.Injection has a constant beginning and variable ending.
B.The pump stroke determines the amount of fuel injected.
C.Fuel is metered by the pump’s delivery valve.
D.Timing reference marks should be changed.
31.Some fuel injection systems utilize port-and-helix metering. Which of the following statement describes a system “timed for port closing”?
A.Injection has a variable beginning and a constant ending.
B.Injection is metered by an external delivery valve.
C.Injection has a constant beginning and variable ending.
D.Injection will not occur until the helix closes the delivery valve
32.An individual injection pump is designed for variable beginning and constant ending of injection. For diesel engines operating at constant speeds, the start of injection will _____________.
A.advance as the load increases
B.retard as the load increases
C.remain unchanged regardless of load
D.always occur at top dead center
33A crankshaft whose center of gravity coincides with its center line is said to be __________.
34.The amount of fuel injected in a particular time, or degree, of crankshaft rotation is termed _____________.
C.rate of injection
D.rate of distribution
35The small end of the connecting rod is attached to the piston with a _____________.
36At dead center, the centerline of the connecting rod usually coincides with the _____________.
A.angularity of the piston motion
B.inertia moment from the piston
C.centerline of the cylinder
D.centerline of the king pin