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Cylinder head recon > Cylinder Head Recon Pt1 > Flashcards

Cylinder Head Recon Pt1 Flashcards

1
Q
A
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2
Q

A head with intake and exhaust ports on OPPOSITE sides is called

A

Crossflow

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3
Q

If the contact made by a valve face and valve seat is too wide or too thin what problem can this cause?

A

Burning of the valve face / seat => loss of seal

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4
Q

2 main materials for cylinder heads

A

Aluminium and cast iron

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5
Q

3 types of fit methods

A
  1. Interference - hole is smaller than insert, held in place by pressure
  2. Clearance - has a clearance to allow for expansion
  3. Neutral / transition - just touching, will allow expansion but not very much
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6
Q

Easiest way to test spring squareness

A

Roll on a flat surface. If rolls in a straight line, it’s square. If rolls in an arc then it’s bent.

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7
Q

4 reasons to machine a cylinder head

A
  1. Make the sealing surface flat so the gasket will seal properly
  2. Raise the compression ratio
  3. Square the head to the block
  4. After welding, straightening or crack repair
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8
Q

3 kinds of valve guide seals

A

Umbrella, positive locking, GM / o-ring

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9
Q

If a cylinder head is warped / bent what should be done about this

A

Will need to be straightened before it can be machined OR probably better off just replacing it.

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10
Q

What causes coking

A

Worn / damaged valve seal or guide

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11
Q

What valve clearance is required for hydraulic lifters?

A

Zero - hydraulic lifters adjust to maintain zero clearance at all times.

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12
Q

3 timing belt profiles

A
  1. Round tooth
  2. Gilmar
  3. Trapezoidal
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13
Q

6 steps to check a cylinder head for servicability

A
  1. Visually inspect for corrosion and damage
  2. Hardness test
  3. Crack test
  4. Check if any parts undersized due to previous machining
  5. Check for warpage / bending
  6. Check for broken studs / threads
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14
Q

When changing a timing belt, what else should be checked

A

Make sure the oil seals will last the life of the new belt. If not, change the oil seals as well.

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15
Q

4 tests performed on valve springs

A
  1. Freestanding height test
  2. Spring squareness
  3. Open close spring pressure test
  4. Collapsed spring height
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16
Q

Where in a valve does the greatest heat transfer take place?

A

Where the face touches the seat

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17
Q

Why is compression limited in petrol engines?

A

Higher compression => higher temperature. At a certain temp the flashpoint of petrol will be reached => uncontrolled explosion instead of controlled burn.

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18
Q

2 advantages of using cast iron for cylinder heads

A
  1. Stronger
  2. Porous so absorbs oil => allows for boundary lubrication
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19
Q

What problem can be caused by a valve not seating properly

A

Inadequate heat transfer can => burnt valve and loss of airtight seal => loss of power

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20
Q

Is lash clearance bigger on intake or exhaust

A

Exhaust - more heat => more expansion

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21
Q

Flame propagation

A

The speed at which flame moves within a combustion chamber.

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22
Q

What is coking

A

Build up of oil that has been heated enough to burn but not enough to ignite.

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23
Q

In what direction to all engines turn

A

Clockwise

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24
Q

What are the 2 main effects of valve rotators

A
  1. Reduce carbon buildup
  2. Reduce hot spots
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25
Q

Another name for tappet adjuster

A

Cam lifter

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26
Q

If the contact point between the valve and seat is too HIGH, what should be done to adjust this.

A

Crown cut the valve seat.

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27
Q

When doing a compression test - hissing coming from the exhaust indicates?

A

Exhaust valve not sealing properly

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28
Q

3 problems that can occur with valve guides

A
  1. Indadequate lubrication
  2. Geometry problem
  3. Wrong stem to guide clearance (e.g. too loose)
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29
Q

What are the 7 methods for cleaning cylinder heads?

A
  1. Hand tools
  2. Chemicals
  3. Pressure washing
  4. Hot/cold tanks
  5. Bead blasters
  6. Thermal cleaners
  7. Ultrasonics
30
Q

When doing a compression test - bubbles in the radiator coolant / sudden rise in coolant level indicate?

A

Air getting into water jacket => probably caused by damaged head gasket.

31
Q

2 types of head gasket

A
  1. Composite
  2. Layered
32
Q

What causes aluminium heads to lose hardness

A

Heat / overheating

33
Q

Another name for cam lifter

A

Tappet adjuster

34
Q

1 Advantage of DOHC configuration

A

Allows different timing for intake and exhaust valves

35
Q

What is 1 way to test whether a valve is intake or exhaust. Why does it work?

A

Exhaust valves are usually made with nickel which is not magnetic.

36
Q
A
37
Q

If the contact point between the valve and seat is too LOW, what should be done to adjust this.

A

Throat cut the valve seat

38
Q

Why is it important to never turn an engine backwards?

A

Can create slack in the belt / chain which may cause it to jump out of alignment when the engine is turned forward again. This would change the timing and may result in damage to the engine (e.g. bent valves)

39
Q

2 types of valve guides. One is used in only what material?

A
  1. Integral
  2. Removable / replaceable

Integral only used in cast iron.

40
Q

5 things not to do to a timing belt

A
  1. Kink,
  2. Twist
  3. Bend
  4. Fold
  5. Get oily
41
Q

When doing a compression test - hissing coming from the air filter area indicates?

A

Inlet valve not sealing properly

42
Q
A
43
Q

After cleaning engine parts what MUST be done to them

A

Sprayed with a rust preventative (e.g. WD40)

44
Q

3 cuts that can be made to a valve seat

A
  1. Crown
  2. Face
  3. Throat
45
Q

Another name for valve clearance

A

Lash

46
Q

What are 2 advantages of a crossflow configuration?

A
  1. Better exhaust scavenging
  2. Cooler intake air
47
Q

Easiest way to test spring freestanding height?

A

Line them up on a flat surface and lay a steel rule across the top

48
Q

Another name for lash

A

Valve clearance

49
Q

If reinstalling a timing belt make sure that

A

Install in the same direction it was before you removed it

50
Q

When reconditioning a cylinder head, what other engine part should be changed out for a new one?

A

The timing belt / chain

51
Q

3 purposes of valve guides

A
  1. Keeps valve face aligned with its seat
  2. Keeps oil out of combustion chamber
  3. Keeps exhaust out of crankcase
52
Q

3 advantages of using aluminium for cylinder heads

A
  1. Lightweight
  2. Easy to produce/machine
  3. Fully recyclable
53
Q

What is the hottest part of an exhaust valve?

A

The fillet

54
Q

When doing a compression test - dipstick movement / shooting out indicates?

A

Piston rings leaking => air getting into sump

55
Q

3 methods of connecting cam & crank shafts for timing

A
  1. Gears
  2. Chain
  3. Belt
56
Q

The 5 key events in an engine are:

A
  1. Intake
  2. Compression
  3. Ignition
  4. Power/Combustion
  5. Exhaust
57
Q

A head with intake and exhaust ports on the SAME side is called

A

Counterflow

58
Q

The contact between the valve face and seat on an INLET valve (in mm)

A

1 - 1.5 mm

59
Q

The contact between the valve face and seat on an EXHAUST valve (in mm)

A

1.5 - 2 mm

60
Q

Why is it important that a valve guide is not too high or too low?

A

I too high will hit the rocker arm. If too low will restrict the valve on return.

61
Q

Cutting with a steel tooth is called what?

A

Milling

62
Q

At what rpm should a cylinder head be milled if it is:

  1. Aluminium?
  2. Cast iron?
A
  1. Aluminium 1000 rpm
  2. Cast iron 850 rpm
63
Q

What precaution should be taken with diesel cylinder heads that have pre-combustion chambers? Why?

A

They must be ground using a stone not milled. The milling tooth won’t cut the pre-combustion chambers as the tooth and the chambers are both steel. So milling will produce an uneven finish, whereas grinding will cut all materials to an equal height.

64
Q

Correct surface finish of a cylinder head is measured using what units?

A

Microns ( µm )

65
Q

What is the symbol for microns?

A

µm

66
Q

How many microns in 1 mm

A

1000 µm = 1 mm

67
Q

7 steps before reinstalling a cylinder head

A
  1. Deburr and coat with preservative
  2. Clean gasket faces
  3. All parts clean and dry
  4. Bolts cleaned and buffed with a wire wheel
  5. Block threads cleaned
  6. Head bolts oiled and / or sealant applied
  7. DON’T clean carbon off piston head or off bore
68
Q

What kind of bolts are usually used for cylinder heads and what is special about them?

A

Torque to yield bolts. Single use only.

69
Q

Tighten these cylinder head bolts in a CROSS / DIAGONAL pattern:

A
70
Q

Tighten these cylinder head bolts in a SPIRAL pattern:

A
71
Q

3 stages of dye crack testing

A
  1. Cleaner
  2. Penetrant
  3. Developer
72
Q

Cylinder heads must be repaired to what specs / standards?

A

OEM specs or better. Must comply to Australian Standards.

Cylinder head recon (2 decks)

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