Deck 32: Camshafts and Valve Trains

Question 1

The camshaft makes ________ for every revolution of the crankshaft.

A)One revolution
B)One half revolution
C)One quarter revolution
D)Two revolutions

Answer 1

One half revolution

Question 2

Flat-bottom valve lifters rotate during operation because of the ________ of the camshaft.

A)Thrust plate
B)Bearings
C)Taper of the lobe
D)Chain tensioner

Answer 2

Taper of the lobe

Question 3

If lift and duration remain constant and the lobe center angle decreases, then ________.

A)Effective duration increases
B)Effective lift increases
C)Valve overlap decreases
D)Valve overlap increases

Answer 3

Valve overlap increases

Question 4

Which timing chain type is also called a "silent chain"?

A)Roller
B)Morse
C)Flat link
D)Both B and C

Question 5

Two technicians are discussing variable valve timing. Technician A says that changing the exhaust valve timing helps reduce exhaust emissions. Technician B says that changing the intake valve timing helps increase low-speed torque. Who is right?

A)Technician A only
B)Technician B only
C)Both technicians A and B
D)Neither technician A nor B

Question 6

Many technicians always use new pushrods because ________.

A)They wear at both ends
B)They are ess expensive to buy than clean
C)All dirt cannot be cleaned out from the hollow center
D)Pushrods shrink in length if removed from an engine

Question 7

A DOHC V-6 has how many camshafts?

A)1
B)4
C)2
D)3

Question 8

The intake valve opens at 39° BTDC (before top dead center) and closes at 71° ABDC (After bottom dead center). The exhaust valve opens at 78° BBDC (before bottom dead center) and closes at 47° ATDC (after top dead center). Which of these is correct regarding this cam timing?

A)Exhaust valve duration is 125°
B)Intake valve duration is 110°
C)Overlap is 86°
D)Both A and B

Question 9

Hydraulic valve lifters can make a ticking noise when the engine is running if ________.

A)Lobe centerline is over 110°
B)Valve lash is too loose
C)Valve lash is too close
D)Both A and C

Question 10

Hydraulic lifters or hydraulic lash adjusters (HLA) may not bleed down properly and could cause an engine miss if ________.

A)The engine oil is 1 quart low
B)The wrong API-rated engine oil is used
C)The wrong SAE-rated engine oil is used
D)Both A and B

Question 11

Technician A says that the pushrods should be rotating while the engine is running if the camshaft and lifters are okay. Technician B says that the camshaft rotates at one-quarter the crankshaft speed. Who is right?

A)Technician A only
B)Technician B only
C)Both technicians A and B
D)Neither technician A nor B

Question 12

Technician A says that silent chains are quieter than roller chains and do not stretch with use. Technician B says that on overhead valve engines, the camshaft is usually placed in the block above the crankshaft. Who is right?

A)Technician A only
B)Technician B only
C)Both technicians A and B
D)Neither technician A nor B

Question 13

Which term is used to describe the number of degrees of crankshaft rotation for which the valve is lifted off the seat?

A)Overlap
B)Underlap
C)Lift
D)Duration

Question 14

Technician A says that valve overlap is the number of crankshaft degrees that both valves are closed. Technician B says that valve overlap is the number of degrees that both valves are open. Who is right?

A)Technician A only
B)Technician B only
C)Both technicians A and B
D)Neither technician A nor B

Question 15

Camshafts turn at which of these?

A)1/2 crankshaft speed
B)Crankshaft speed
C)1/4 crankshaft speed
D)Twice crankshaft speed

Question 16

If the exhaust valve opens at 57° before BDC (before dead center) and closes at 29° after TDC (top dead center), what is the exhaust valve duration in degrees?

A)237
B)266
C)209
D)86

Question 17

What determines the amount of valve overlap?

A)Camshaft design
B)Total lift in degrees
C)Cam lobe accuracy
D)Timing gears or chain

Question 18

Valve lifters are designed in which of these ways?

A)Cut at an angle
B)Dome shaped to assist in rotation
C)Only replaced in complete sets
D)Ground on one side to compensate for cam offset

Question 19

On an engine with variable cam timing, the cam timing can be changed by use of ________.

A)A spline cam phaser
B)A vane cam phaser
C)Either of these
D)Neither of these

Question 20

Two technicians are discussing an engine with an interference design. Technician A says if a valve remains open when its cylinder reaches TDC, the piston may strike the valve. Technician B says if a valve remains open when its cylinder reaches TDC, valvetrain damage can result. Which technician is correct?

A)Technician A only
B)Technician B only
C)Both technicians A and B
D)Neither technician A nor B

Question 21

On a vehicle with cylinder deactivation, the valves are kept closed by deactivating the ________.

A)Valve lifter
B)Cam lobe
C)Valve spring
D)Valve stem

Question 22

A cylinder deactivation system uses ________ ________ to operate the system.

A)Oil pressure
B)Roller pumps
C)Magnetic induction
D)None of these

Question 23

Variable cam timing technology is used on the exhaust cam only.

Question 24

The PCM controls cam timing by use of ________.

A)A variable spring
B)A pulse width modulated (PWM) signal
C)A variable chain tensioner
D)A reluctor regulator

Question 25

The valves could be bent if the timing belt breaks on which of these?

A)Freewheeling engine design
B)Interference engine design
C)Undersquared engine
D)In-block cam engine

Question 26

The movement of the camshaft lengthwise in the engine during operation is controlled by ________ between the camshaft drive gear or sprocket and a flange on the camshaft.

A)Rotational compensator
B)Thrust plate
C)Shim
D)Lock washer

Question 27

Identify this component.

A)Flat lifter
B)Roller lifter
C)Intake check valve
D)Oil pump