Deck 9: Camshafts, Lifters, Timing Belts, and Chains

Question 1

What is meant by the term, valve overlap?

Answer 1

Valve overlap is the period when the intake and exhaust valves are both open.

Question 2

What is an interference engine?

Answer 2

On some engines, piston-to-valve interference can occur if the timing chain or belt skips or breaks. These engines are called nonfreewheeling or interference engines.

Question 3

Technician A says valve overlap occurs at the bottom of the intake stroke. Technician B says valve overlap occurs at the top of the intake stroke. Who is correct?

A)Technician A
B)Technician B
C)Both technicians
D)Neither technician

Answer 3

B

Question 4

Two factors of cam lobe profile are called lift and length.

Question 5

Technician A says sometimes the exhaust lobe on the camshaft will wear quickly and more severely than the intake. Technician B says the roller cam cuts valvetrain friction by 75%. Who is right?

A)Technician A
B)Technician B
C)Both technicians
D)Neither technician

Question 6

Technician A says a new or rebuilt engine should have the idle maintained above 1500 rpm for at least 20 minutes to insure proper lubrication and break in. Technician B says long periods of idle are hard on the camshaft. Who is correct?

A)Technician A
B)Technician B
C)Both technicians
D)Neither technician

Question 7

Camshafts are being discussed. Technician A says cam journals rarely wear so they do not need to be reground. Technician B says reground cams are more expensive. Who is correct?

A)Technician A
B)Technician B
C)Both technicians
D)Neither technician

Question 8

In reference to fuel use, what is CAFE?

Question 9

With regard to gear drives, what is backlash?

Question 10

The camshaft is the determining factor in how efficiently the engine pumps air.

Question 11

Timing belt sprockets should be cleaned with a petroleum-based solvent.

Question 12

Lifters are being discussed. Technician A says there is only 0.0002" of clearance between the plunger and lifter body. Technician B says dirt particles in an engine are generally larger than 0.0002". Who is right?

A)Technician A
B)Technician B
C)Both technicians
D)Neither technician

Question 13

Technician A says on most pushrod engines, lifters have a concave face. Technician B says pushrods are stationary when the engine is running. Who is correct?

A)Technician A
B)Technician B
C)Both technicians
D)Neither technician

Question 14

Before using a chain wrench to hold a pulley in order to torque the crank bolt, what should you do?

Question 15

Technician A says that a gear on the camshaft drives the distributor. Technician B says the exhaust and intake valves each operate on a separate lobe on the camshaft. Who is correct?

A)Technician A
B)Technician B
C)Both technicians
D)Neither technician

Question 16

All of the following are timing components EXCEPT _____.

A)chain
B)belt
C)tensioner
D)lifter

Question 17

Technician A says camshaft end thrust on some engines is controlled by the distributor. Technician B says timing can change if camshaft end thrust is not controlled. Who is right?

A)Technician A
B)Technician B
C)Both technicians
D)Neither technician

Question 18

Technician A says on a pushrod engine, the lifters do not need to be replaced when the camshaft is replaced. Technician B says when replacing a roller camshaft, the lifters must be replaced. Who is correct?

A)Technician A
B)Technician B
C)Both technicians
D)Neither technician

Question 19

Pressures on a lifter can reach 100,000 psi.

Question 20

Another term for mechanical lifter is tappet.

Question 21

Technician ​A says that valve lifters are sometimes called "tappets." Technician B says that hydraulic lifters should leak very slowly between the plunger and the lifter body. Who is right?

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

Question 22

When there is no clearance between the valve stem and its actuator, this is known as _____.

Question 23

When a worn lifter face contacts the outside edge of a flat tappet cam lobe causing severe wear, this is called edge _____.

Question 24

The _____ circle is what the cam would be if there were no lobe.

Question 25

List two other names for valve lifter.
A.
B.

Question 26

Technician ​A says that excessive hydraulic lifter pump-up can occur if the valves float. Technician B says that hydraulic lifter valve adjustment on most engines positions the plunger at its center of travel in the lifter body. Who is right?

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

Question 27

What is the term for the pushrod engine hydraulic lifter adjustment accomplished simply by torquing the adjusting nut against a shoulder?

Question 28

On a pushrod engine, all of the following are true except: ​

A)Valve lash increases as pushrods and rocker arms wear.
B)Valve lash increases as the valve and seat wear.
C)A decrease in lash can cause improper valve cooling and can lead to burned valves.
D)All of the above

Question 29

When a cam lobe wears out, which will it most likely be?
A. Intake
B. Exhaust

Question 30

As the oil pump in a pushrod engine is turned, resistance to pumping the oil causes the cam to be forced toward the rear of the engine. What is this motion called?

Question 31

How many camshafts does a DOHC V6 have?

Question 32

On pushrod flat tappet engines, why is the cam lobe tapered and the lifter off-center?

Question 33

What name describes an engine that can have a collision between the piston and valve when the timing chain or belt breaks?

Question 34

What part is replaced along with a timing belt when an engine does not have a tensioner bearing?

Question 35

What is the term for the period when the intake and exhaust valves are both open?

Question 36

To drive the oil pump and distributor, some overhead cam (OHC) engines use an extra shaft called a(n) _____ shaft that is driven by the crankshaft using an extra sprocket.

Question 37

When there is a spiral gear on the camshaft of a pushrod engine, what is its purpose?

A)It drives the distributor.
B)It drives the oil pump.
C)Both of the above
D)Neither of the above

Question 38

When there is too much valve lash on a mechanically adjusted valvetrain, the lifter or cam follower can miss the _____ ramp.

Question 39

Technician ​A says that a camshaft thrust spacer that is too narrow can cause fluctuations in ignition timing. Technician B says that excessive timing chain slack can be verified on a pushrod engine with a distributor by turning the crankshaft by hand while watching to see if the distributor moves. Who is right?

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

Question 40

The camshaft term for the number of degrees of crankshaft travel that the valve is off its seat is called _____.

Question 41

Technician ​A says that camshaft end thrust on a pushrod engine with a camshaft-driven oil pump results from resistance of oil being pumped by the oil pump. Technician B says that flat tappet camshafts are usually inspected by visually checking the wear pattern on the lobes for edge loading. Who is right?

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

Question 42

Two technicians are discussing flat tappet camshafts. Technician A says that a valve lifter must be perfectly centered above its corresponding cam lobe. Technician B says a pushrod engine cam lobe is slightly tapered across its face. Who is right?

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

Question 43

The exhaust valves shown in the preceding photograph are from a four cylinder interference engine that has failed. All of the valves are bent an equal amount. Which of the following could be the cause?

A)A broken timing belt
B)Excessive chain slack
C)Either of the above
D)None of the above

Question 44

The cam lobes in the photograph shown here are for the number one cylinder and its companion on an in-line pushrod engine that rotates counterclockwise when viewed from the rear. The lobes are positioned:

A)At TDC at the beginning of the compression stroke
B)At TDC at the beginning of the intake stroke
C)None of the above

Question 45

Technician A says that it is necessary to keep flat tappets in order if the old cam and lifters are to be used again. Technician B says that used roller tappets should not be installed on a new camshaft. Who is right?

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