Deck 12: Upper End Theory and Service

Question 1

To protect against scuffing and wear, some valves have coatings of black nitride applied to the valve stem.

Answer 1

True

Question 2

Aluminum cylinder head bolts should never be loosened or tightened when the metal is hot.

Answer 2

True

Question 3

Technician A says the valve seats must be ground before the valve guides are serviced. Technician B says before grinding the valve seats, they should be checked for cracks. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Answer 3

B

Question 4

The performance of an engine, its fuel efficiency, and its exhaust emissions all depend to a large extent on the shape of the combustion chamber.

Question 5

The hemispherical combustion chamber provides excellent turbulence to the air and fuel mixture.

Question 6

A single hole in the cylinder head that divides into two branches is called a _____ port.

A) dual
B) siamese
C) combination
D) two-stage

Question 7

A typical interference angle is _____ degree(s).

A) 30
B) 1
C) 45
D) 46

Question 8

Which of the following can be reconditioned by grinding?

A) valve face
B) valve tip
C) both "valve face" and "valve tip"
D) neither both "valve face" nor "valve tip"

Question 9

Resurfacing a cylinder head gasket surface may alter the combustion chamber volume.

Question 10

Powder metal valve seats are softer and do not last as long as cast iron seats.

Question 11

Aluminum expands and contracts almost twice as much as cast iron in response to temperature changes.

Question 12

To ensure proper seating of the valve, the valve seat must _____.

A) be the correct width
B) have the correct location on the valve face
C) be concentric with the guide
D) all answers are correct

Question 13

Many camshaft journals run directly on aluminum supports and do not use bearing inserts.

Question 14

Sodium-filled valves should be cut open for inspection.

Question 15

What is typically the maximum amount of warpage that is acceptable on a cast-iron cylinder head?

A) 0.002 in. (.05 mm)
B) 0.003 in. (.076 mm)
C) 0.004 in. (.102 mm)
D) 0.005 in. (.127 mm)

Question 16

Aluminum cylinder heads weigh roughly half as much as cast-iron heads.

Question 17

Which of the following is NOT true of knurling?

A) It is one of the fastest techniques for restoring the inside diameter (ID) dimension of a worn valve guide
B) It reduces the amount of work necessary to reseat the valve
C) It is useful for restoring badly worn guides to their original condition
D) None of these answers is correct

Question 18

A cylinder head may be made of cast iron or aluminum.

Question 19

Which type of surfacing machine uses underside rotary cutters?

A) milling
B) broaching
C) belt
D) grinding

Question 20

Stainless steel is nonmagnetic.

Question 21

Multiple valve engines tend to be more efficient than engines with two valves per cylinder because:

A) larger valve area improves the air flow in and out of the cylinder
B) air velocity is increased-especially at low engine speed; this increases air flow
C) smaller and lighter valves require less spring tension-less engine power is lost to spring opening drag
D) all answers are correct

Question 22

Induction-hardened integral valve seats are found on _____ cylinder heads.

A) aluminum
B) cast iron
C) both "aluminum" and "cast iron"
D) neither "aluminum" nor "cast iron"

Question 23

Technician A says heat is transferred from an exhaust valve to the cylinder head through the valve seat. Technician B says some exhaust valves have a hollow stem filled with silicone to transfer heat to the valve guide. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 24

_____type valve stem seals move up and down with the valve stems to deflect oil away from the guides.

A) Positive
B) Umbrella
C) O-ring
D) Lip

Question 25

Technician A checks for bent pushrods by rolling them on a flat surface. Technician B checks for bent pushrods using a dial indicator and V-blocks. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 26

Technician A uses a 30-degree stone for topping a 45-degree valve seat. Technician B uses a 60-degree stone to lower a 45-degree valve seat. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 27

Technician A says multivalve engines have a more complete combustion than conventional engine designs. Technician B says the benefits of multivalve engines are offset to some extent because a more complicated camshaft arrangement is needed. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 28

Prussian blue or machinist dye is used to ______.

A) measure stem-to-guide clearance
B) measure valve runout
C) mark the position of cam bearings prior to removal
D) check the width and position of the valve-to-seat contact pattern

Question 29

Hemispherical combustion chambers are being discussed. Technician A says the flame path from the spark plug to the piston head is short, which provides efficient burning. Technician B says cross-flow arrangement of the inlet and exhaust valves allows for a relatively free flow of gases in and out of the chamber. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 30

Cylinder head warpage can be measured with _____.

A) a straightedge and feeler gauge
B) a dial indicator
C) a surface gauge
D) a ball gauge and outside micrometer

Question 31

Technician A says positive valve stem seals fit tightly around the top of the stem. Technician B says positive stem seals scrape oil off the valve as it moves up and down. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 32

Technician A says multivalve engines can have three valves per cylinder. Technician B says multivalve engines can have five valves per cylinder. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 33

Valve springs should be checked for all of the following EXCEPT:

A) freestanding height
B) squareness
C) compressed height
D) open pressure

Question 34

Resurfacing the cylinder head can affect _____.

A) compression ratio
B) valve timing
C) piston to valve clearance
D) all answers are correct

Question 35

Technician A says if valve stem height exceeds specifications, it can be adjusted by grinding the valve tip. Technician B says the valve stem height can be adjusted with shims. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 36

A pentroof combustion chamber is normally found on a(n) _____type cylinder head.

A) OHV
B) four valve per cylinder
C) two valve per cylinder
D) VVT [variable valve timing]

Question 37

Technician A says worn valve stem seals can increase oil consumption. Technician B says worn valve stem seals can cause valve deposits. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 38

After resurfacing a valve seat at 45 degrees, the seat is too wide and the contact pattern extends all the way up to the valve margin. What should be done to bring the seat width into specifications?

A) Make a 30-degree topping cut
B) Make a 45-degree seat cut
C) Make a 60-degree throat cut
D) Replace the valve

Question 39

Valve guides are _____.

A) integral [bores in cylinder head]
B) pressed in cast iron inserts
C) pressed in bronze inserts
D) all answers are correct

Question 40

Technician A says VVT [variable valve timing] engines use a cam phaser that advances or retards the camshaft as the engine is running. Technician B says VVT engines use a third cam lobe with increased lift and duration, operating a third rocker arm that is coupled to the two primary rocker arms by a hydraulically controlled pin, while the engine is running. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 41

A cylinder head that has the intake manifold and all the intake valves on one side and the exhaust manifold and exhaust valves on the opposite side is called a ____________________type cylinder head.

Question 42

Technician A resurfaces valve seats using a grinding stone. Technician B resurfaces valve seats using a cutting blade. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 43

What procedures should be followed after refinishing a valve face?

Question 44

____________________ support the valve in the head and prevent the valve from moving in any direction other than up and down.

Question 45

Installed spring height [the distance between the spring seat and the bottom of the retainer] can be measured with a spring height gauge or ____________________.

Question 46

The distance between the valve face and the head of the valve is called the ____________________.

Question 47

The surface of a valve that comes into contact with the valve seat is called the valve ____________________.

Question 48

Technician A says the end of the valve spring that is wound the tightest should face toward the spring retainer. Technician B says the O-ring seal should be installed in the lowest of the keeper grooves on the valve stem.

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 49

Describe a phaser.

Question 50

How does refinishing a valve face and the valve seat affect its position in the cylinder head?

Question 51

Describe a hemispherical combustion chamber.

Question 52

While disassembling a cylinder head, what would indicate that the valve seals are worn or damaged?

Question 53

Why does a properly finished valve seat have three different angles?

Question 54

Where on the cylinder head are cracks most likely to occur?

Question 55

What is the function of a rocker arm?

Question 56

Installed valve spring height can be adjusted with ____________________.

Question 57

Valve stem wear may be measured with a ____________________.

Question 58

The type of valve used in automotive engines is called a ____________________.

Question 59

The camshafts and timing gears are removed from the cylinder head. A technician covers the return oil holes in a camshaft with electrical tape and applies compressed air to the other oil hole. With the camshaft held stationary, the timing gear rotates a few degrees counterclockwise. When the air pressure is released, the timing gear rotates clockwise back to its original position. This proves that the ____________________ is working properly.

Question 60

____________________ is a very rapid movement of gases that causes the air and fuel to mix better and improve combustion.

Question 61

What happens when valve spring tension is too low?

Question 62

What is the most common cause of warpage in an aluminum cylinder head?