Deck 10: Camshafts and Valvetrains

Question 1

Depending on the design of the rocker arm, they have the ability to change valve duration with different ratios.

Answer 1

False

Question 2

In order for a camshaft to make one full rotation, the crankshaft will rotate 720 degrees.

Answer 2

True

Question 3

Clattering noise from the top of the engine can be caused by too much valve clearance.

Answer 3

True

Question 4

Camshaft duration is the amount of time a valve stays open during engine operation measured in milliseconds.

Question 5

Technician A says that you must compress the valve spring onto the cylinder head before you can install an O-ring valve stem seal. Technician B says that positive-type valve stem seals are installed before the valve spring. Who is correct?

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

Question 6

Hydraulic lifters are designed to maintain a zero lash and are typically quieter in operation as compared to their solid counterparts.

Question 7

Engines with VTEC (variable timing electronic control) vary the valve duration to increase engine performance.

Question 8

When the valve is closed, the rocker arm should be dead center on the valve stem tip.

Question 9

Technician A says that hydraulic lifters are adjusted when the valves are open so that the plunger may be put into a centered position. Technician B says that solid lifters require adjustment over time as engine parts wear. Who is correct?

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

Question 10

Technician A says that it is possible to replace press-in type rocker arm studs with threaded ones by milling, then using a tap to thread the boss in the head. Technician B says that it is good practice to replace stamped steel rocker arms during an overhaul. Who is correct?

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

Question 11

Valve overlap defines what happens in a combustion chamber when the valves are both closed at the same time.

Question 12

Technician A says that camshaft journals are measured for out-of-round and taper. Technician B says that most OHV engines have different size journals. Who is correct?

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

Question 13

Technician A says that a warpage of 0.300" (7.62mm) is acceptable for most pushrods. Technician B says that some pushrods are hallow in design to oil valvetrain components. Who is correct?

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

Question 14

All of the following are true about OHV camshafts and lifters EXCEPT ____.

A) hydraulic lifters should be tested for leak-down during inspection if they are to be reused
B) the normal shape for the bottom of a lifter is concave
C) new lifters should always be installed on a new camshaft
D) lifters must always be installed on the same lobe for which it was removed

Question 15

During inspection of the rocker arm geometry, the rocker arm is contacting the tip of the valve stem excessively to one side. Technician A says that pushrod length may be changed to correct the problem. Technician B says that rocker arm length may be changed to correct the problem. Who is correct?

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

Question 16

Improper valve spring pressure can cause valve float.

Question 17

The adjustment of mechanical lifters is being discussed. Technician A says that lifters adjusted with too much clearance could result in burned valves. Technician B says that lifters adjusted with too much clearance will result in decreased valve lift and duration. Who is correct?

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

Question 18

An intake valve will typically be open at 15 degrees ATDC during the intake stroke.

Question 19

Two technicians are discussing camshafts.Technician A says that increased valve overlap is caused by camshaft lobe wear. Technician B says that most OHV engines have variable valve timing in order to improve performance and reduce emissions . Who is correct?

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

Question 20

Technician A says that valve springs should be checked for squareness and pressure. Technician B says that seat pressure is measured with the spring compressed to the same height it would be when installed and the valve closed. Who is correct?

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

Question 21

Explain how to measure camshaft straightness.

Question 22

Technician A says that valve lash can be adjusted on a cylinder that is at TDC and on the compression stroke. Technician B says that feeler gauges are used when adjusting hydraulic lifters. Who is correct?

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

Question 23

What part of the camshaft causes the valve to open and close?

Question 24

What percentage of the manufacturer's specification should spring tension be within?

A) 1%
B) 5%
C) 10%
D) 20%

Question 25

What is the procedure for adjusting hydraulic lifters on a prepared and running engine that has adjustable rocker arms?

Question 26

When the camshaft is installed in the engine, what tool may be used to measure valve lift?

Question 27

A customer comes into a shop with a complaint that his car is smoking. The smoke appears in a big cloud after starting and then clears up. He also notes smoking during long periods of deceleration or idling. Technician A says that the valve stem seals may be worn. Technician B says that if the valve stems are worn, they may be changed without removing the cylinder head. Who is correct?

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

Question 28

What is installed on the inside of some valve springs to control vibrations?

Question 29

A cylinder head is being reassembled after having the face and seat resurfaced. Technician A says that this will increase the valve stem height. Technician B says that a shim within the size recommendation of the manufacturer may be installed under the spring to correct for this. Who is correct?

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

Question 30

When adjusting hydraulic valve lifters, to what position should the plunger be set when the valve is closed?

Question 31

Beside normal seal wear, what could cause positive-type valve guide seals to fail prematurely?

Question 32

Describe the inspection performed on a solid pushrod using no special tools.

Question 33

What steps must be taken to properly install an O-ring style valve stem seal?

Question 34

What are two reasons manufacturers install rotators on valves?

Question 35

Technician A says that valve spring free height is checked with the spring installed and under pressure. Technician B says that coil bind is checked with the valve closed. Who is correct?

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

Question 36

What type of valve springs are designed with unequally spaced coils?

Question 37

When the mating surface of an OHV cylinder head is surfaced, what may be affected after the head is installed and the valves are adjusted?

Question 38

If a camshaft has a lobe lift of .324", and a rocker arm ratio of 1.5:1, what is the lift at the valve?

Question 39

What is it referred to as when the valve opens and the valve spring is compressed flat until it cannot be compressed any more?

Question 40

All of the following are reasons to replace a valve spring EXCEPT ____.

A) cracks
B) pitting
C) nicks
D) an excess of 100,000 miles

Question 41

What factors should be considered when selecting an aftermarket camshaft for performance?

Question 42

Why is spring squareness important and how is it checked?

Question 43

Technician A says that hydraulic lifters can collapse or leak down into the centered position. Technician B says that roller lifters require a roller-type camshaft. Who is correct?

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