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Automotive Level 1 > Engine Fundamentals > Flashcards

Engine Fundamentals Flashcards

1
Q

What is compression ratio?

A

The ratio from BDC to TDC

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2
Q

What is the best way to describe the noise caused by piston slap?

A

Hollow bell like noise

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3
Q

What engine test can be used to pinpoint the cause of a low cylinder compression test result?

A

A cylinder leakage test

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4
Q

What could be the cause of indicated by good results from a compression test but poor results from a cylinder power balance test?

A

A collapsed lifter

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5
Q

What are the best names for the four-strokes?

A

Intake, Compression, Power, Exhaust

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6
Q

What is piston slap?

A

Noise made by the piston when it contacts the cylinder wall

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7
Q

During a cylinder leakage test where would you expect to find/ hear the air from if the piston rings were worn?

A

The oil fill port, dipstick tube

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8
Q

During a cylinder leakage test where would you expect to find/ hear the air from if a leaking intake valve was present

A

Throttle plate

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9
Q

During a cylinder leakage test where would you expect to find/ hear the air from if a leaking exhaust valve was present

A

Exhaust pipe

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10
Q

During a cylinder leakage test where would you expect to find/ hear the air from if a head gasket is blown

A

Radiator

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11
Q

What is the stroke of the piston equal to

A

Two times the crankshaft throw

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12
Q

What is an expression of how much of the heat formed during the combustion process is available as power from the engine

A

Thermal efficiency

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13
Q

Which stroke in the four stroke cycle begins as the compressed fuel mixture is ignited in the combustion chamber?

A

Power Stroke

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14
Q

What would cause a sharp metallic rapping sound that originates in the upper portion of the engine and is mist pronounced during idle?

A

Worn piston pins

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15
Q

As an engines compression ratio increases, what should happen to the octane rating of the gasoline?

A

It should increase to avoid detonation

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16
Q

What engine type typically has the highest compression ratio?

A

Diesel

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17
Q

What would cause a higher than normal oil pressure test reading?

A

A defective oil pressure regulator valve

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18
Q

What engine component is responsible for opening and closing the intake and exhaust valves?

A

Camshaft

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19
Q

What test can be performed to check the efficiency of individual cylinders?

A

Cylinder balance test

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20
Q

Tappet noise is best described as

A

Noisy Valve train components

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21
Q

RTV is ________

A

Aerobic

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22
Q

Explain Firing order

A

The order in which an engines pistons are on their compression stroke and the order in which the spark plugs ignite.

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23
Q

What is the bore of a cylinder

A

The cylinders diameter measured in mm or in

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24
Q

What is the stoke

A

The distance the piston travels between TDC and BDC

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25
Q

What does the bore and stroke determine

A

The displacement of the cylinders

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26
Q

What does a square engine refer to

A

When the bore and stroke are equal sizes

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27
Q

What is an oversquare engine

A

Engines that have a larger bore than stroke

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28
Q

What is an undersquare engine

A

Engines that have a larger stroke than bore

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29
Q

Which kind of engine can be fit with larger valves and shorter connecting rods and are more capable of running at higher speeds?

A

Oversquare Engines

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30
Q

What engines use longer connecting rods that aid in the production of more power at lower engine speeds?

A

Undersquare Engines

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31
Q

What is crank throw

A

The distance from the crankshafts main bearing centerline to the crankshaft connecting rod journal.

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31
Q

What is a cylinders displacement

A

The swept volume of the cylinder. The volume of the cylinder from BDC to TDC.

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32
Q

An engines displacement is ___________

A

The sum of the displacements of each of the engines cylinders

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33
Q

The higher the compression ratio ________

A

The more power an engine can produce

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34
Q

Volumetric Efficiency refers to :

A

The engines ability to fill its cylinders with the air fuel mix

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35
Q

Thermal Efficiency refers to:

A

A measure of how much of the heat formed during combustion is available as power from the engine.

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36
Q

What can increase Volumetric Efficiency?

A

Turbochargers and Superchargers

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37
Q

What is Mechanical Efficiency?

A

Power available vs. power exherted

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38
Q

Torque is : ________

A

A twisting or turning force

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39
Q

Horsepower is : ___________

A

The rate at which the torque is produced

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40
Q

Which four stroke engine holds the intake valve open longer during the compression stroke?

A

Atkinson Cycle Engine

41
Q

An Atkinson cycle engine with forced induction (supercharger) is called what?

A

A Miller Cycle Engine

42
Q

What happens to engine vacuum as rpms increase if the throttle plates are closed

A

Vacuum will increase

43
Q

What happens to engine vacuum when the throttle plates are open

A

Vacuum will decrease

44
Q

What is Ring Noise and when can it be heard

A

Can be heard during acceleration as a high-pitched rattling or clicking in the upper part of the engine.

45
Q

What can cause Ring Noise

A

Worn rings or cylinders, broken piston ring lands, insufficient ring tension against the cylinder walls

46
Q

When is Piston Slap commonly heard?

A

When the engine is cold and often gets louder with acceleration

47
Q

What does Piston Pin Knock sound like

A

A sharp metallic rap that can sound more like a rattle if all the pins are loose

48
Q

What is Rod Bearing Noise and when is it most commonly heard?

A

It is the result of worn or loose connecting rod bearings and is most commonly heard at idle or cruising speeds and during deceleration.

48
Q

What causes Piston Pin Knock

A

Worn Piston pins, piston pin bushing, lack of lubrication

49
Q

What is Detonation often caused by?

A

Advanced ignition timing, substantial carbon build up, Fuel octane that is too low

50
Q

What does a basic short block consist of?

A

The block, crankshaft, crankshaft bearings, connecting rods, pistons and rings, and oil gallery and core plugs

51
Q

Chamfering or counterboring will __________

A

Eliminate thread pulls and jagged edges

52
Q

Taper is _____________

A

The difference in diameter between the bottom of the cylinder bore and the top of the bore. Subtracting the smaller diameter from the bigger one

53
Q

What causes glaze on cylinder walls?

A

Combustion heat, engine oil and piston movement

54
Q

Bearing spread ensures : ______________

A

Positive positioning against the inside of the bore and helps keep bearings in place during assembly

54
Q

What are crankshafts generally made of?

A

Cast iron,cast steel and nodular iron

55
Q

What is Plastigage and what is it used for

A

A fine plastic string used to measure the oil clearance between the bearing and the crankshaft

56
Q

The connecting rod helps: ________

A

Transmit the pressure applied on the piston to the crankshaft

57
Q

Maximum valve margin clearance is

A

1/32 of an inch

58
Q

What can cause oil to enter the combustion chamber

A

Worn valve seats and guides, worn piston rings

59
Q

How do you calculate cylinder displacement?

A

pie x r2 x stroke

60
Q

How much pressure does a cylinder head gasket have to hold

A

1500 psi

61
Q

Many camshafts use what instead of bearing inserts

A

Aluminum supports

62
Q

Max allowable warpage of a V8 cylinder head is?

A

0.004 in

63
Q

Max allowable warpage of a V6 cylinder head is?

A

0.003 in

64
Q

Max allowable warpage of an inline 6 is?

A

0.006 in

65
Q

How do you correct excessive valve stem height?

A

Grind the material from the valve stem tip

66
Q

When should a valve be discarded

A

If it has cracks or it has damaged keeper grooves

67
Q

What is recommended before removing the valves from a cylinder head?

A

Measure the valve spring height

68
Q

How many degrees of crankshaft rotation are required to complete a four stroke cycle in one cylinder?

A

720

69
Q

What is the procedure for removing cylinder head bolts?

A

They are removed in the reverse order of assembly

70
Q

Low compression in two side by side cylinders is likely what?

A

A leaking head gasket

71
Q

Valves being ground with an interference angle is referring to the angles between what components?

A

Valve face and valve seat

72
Q

How are integral valve guides reconditioned?

A

By installing bronze guides and reaming the guide for an oversize valve stem

73
Q

To narrow and lower a 45 degree valve seat the tech should use a _____________ stone

A

30 Degrees

74
Q

To widen a 45 degree valve seat without raising or lowering its position the tech should use a ________ stone

A

45 degree

75
Q

What are valve springs checked for?

A

Tension, free height and squareness

76
Q

What type of valve spring uses two springs wound in opposite directions?

A

Dual springs

77
Q

How is excessive valve stem height usually corrected?

A

Replacing the valve seat

78
Q

Valve spring installed height can be adjusted by

A

Installing valve spring inserts (shims)

79
Q

Which type of valve seal moves up and down with the valve?

A

Umbrella seals

80
Q

What is required of the valve face contact surface to ensure proper seating of the valve

A

It should be concentric with the guide

81
Q

Why do multiple valve engines tend to be more efficient than engines with two valves per cyl

A

They provide less restriction to the airflow

82
Q

O ring seals are located where on the valve stem

A

Between the stem and the valve guide

83
Q

Crankshaft endplay can be checked with

A

Feeler gauge, Dial indicator

84
Q

What does bearing crush help

A

Ensure good contact between the bearing and the housing

85
Q

The maximum taper and out of roundness of a crankshaft journal is

A

0.001 in

86
Q

What are the two basic designs of bearing inserts?

A

Full round (one piece) , Split (two piece)

87
Q

3 Types of core plugs

A

Expansion, Dished and Cup

88
Q

What material are camshaft bearings made of?

A

Aluminum or steel with a lining of babbitt

89
Q

Common compression rings are made of

A

Cast iron, Cast iron coated with moly, Cast coated with chrome

90
Q

Most common ways to measure cam lobe wear

A

Dial indicator and outside micrometer

91
Q

What are the three names of piston rings on modern day pistons

A

Top compression, Bottom compression and oil control ring

92
Q

What is cylinder boring

A

When surfaces are badly worn or excessively scored or tapered boring is done to cut the cylinders for oversize pistons or sleeves

93
Q

What is cylinder honing

A

The use of honing stones to deglaze and replace the crosshatch finish that is necessary

94
Q

What are most modern day pistons made of?

A

Aluminum alloyed with, copper, magnesium, nickel and silicon

95
Q

What are the two types of basic piston skirts?

A

The slipper and full skirt

96
Q

What are the three reasons for resurfacing the deck surface of a cylinder head

A

To make the surface flat
To raise compression ratio
To square the deck to the main bores

97
Q

In general the maximum deformation of a cylinder head allowed is

A

0.004 in

98
Q

Today most valves are made from _______

A

Special hardened steel, steel alloys, or stainless steel

99
Q

Out-of-roundness is
measured at the top of
the cylinder just below
the ridge. Typically, the
maximum allowable out-of-
roundness is

A

0.0015 in

Automotive Level 1 (3 decks)

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