Question 1

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?

Accepted Answer

B

Question 2

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?

Accepted Answer

Technician A is correct. The exhaust lobe on the camshaft is exposed to more heat, gases, and wear than the intake lobe, so it's possible for it to wear more quickly and severely. Technician B is incorrect. While roller cams do cut down on valvetrain friction, the amount of reduction is not a set percentage and can vary depending on the specific cam design and the components being used.

Question 3

In reference to fuel use, what is CAFE?

Accepted Answer

Corporate Average Fuel Economy (CAFE) are the fuel economy standards passed by the United States Congress in 1975.

Question 4

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?

Accepted Answer

The answer of Technician A says on most pushrod engines,...

Question 5

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?

Accepted Answer

The answer of Technician A says on a pushrod engine,...

Question 6

With regard to gear drives, what is backlash?

Accepted Answer

The answer of With regard to gear drives, what is...

Question 7

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?

Accepted Answer

Both technicians are correct. The gear on the camshaft does drive the distributor, and the exhaust and intake valves are operated by separate lobes on the camshaft.

Question 8

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

Accepted Answer

The camshaft controls the opening and closing of the engine's valves, which directly affects the intake and exhaust of air. Therefore, it plays a crucial role in the engine's ability to efficiently pump air.

Question 9

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

Accepted Answer

The answer of Before using a chain wrench to hold...

Question 10

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?

Accepted Answer

The answer of Camshafts are being discussed. Technician A says...

Question 11

What is an interference engine?

Accepted Answer

The answer of What is an interference engine?...

Question 12

What is meant by the term, valve overlap?

Accepted Answer

The answer of What is meant by the term, valve...

Question 13

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?

Accepted Answer

The answer of Technician A says a new or rebuilt...

Question 14

Pressures on a lifter can reach 100,000 psi.

Accepted Answer

Pressures on a lifter can reach up to 100,000 psi, making them capable of lifting heavy loads.

Question 15

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?

Accepted Answer

Both statements made by Technician A and Technician B are correct. The clearance between the plunger and lifter body in hydraulic lifters is indeed very small, typically around 0.0002 inches, to maintain proper hydraulic pressure and function. Technician B's statement is also correct because dirt particles found in engine oil are generally larger than 0.0002 inches, which is why maintaining clean oil and proper filtration is crucial to prevent lifter and engine damage.

Question 16

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

Accepted Answer

Lift refers to the total distance that the camshaft pushes the valve open, while length refers to the duration of the lift (how long the valve stays open).

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?

Accepted Answer

The answer of Technician A says camshaft end thrust on...

Question 18

Another term for mechanical lifter is tappet.

Accepted Answer

Mechanical lifter and tappet are interchangeable terms to describe the same component in an engine.

Question 19

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

Accepted Answer

Timing belt sprockets should be cleaned with a petroleum-based solvent to remove any dirt, debris, or oil buildup that may interfere with the performance of the timing belt. This is important because any contaminants on the sprockets can cause the belt to slip or wear out prematurely, leading to engine damage. It is recommended to use a non-chlorinated solvent to avoid any potential damage to the timing belt or sprockets.

Question 20

All of the following are timing components EXCEPT _____.

Accepted Answer

A lifter is not a timing component, it is part of the valve train system in an engine. The chain, belt, and tensioner are all important timing components that work together to keep the engine's camshaft and crankshaft synchronized.

Quiz 9: Camshafts, Lifters, Timing Belts and Chains