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© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Publisher The Goodheart-Willcox Co., Inc. Tinley Park, Illinois.

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Presentation on theme: "© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Publisher The Goodheart-Willcox Co., Inc. Tinley Park, Illinois."— Presentation transcript:

1 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Publisher The Goodheart-Willcox Co., Inc. Tinley Park, Illinois by Russell Krick

2 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only

3 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  Cylinder head construction  Valve train construction  Intake manifold construction  Exhaust manifold construction

4 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Engine Top End Includes the cylinder head, valve train, valve cover, and intake and exhaust manifolds

5 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  A bare cylinder head is a head casting with all of its parts removed  If a cylinder head becomes damaged, the technician may need to install a new bare head  All the old, reusable parts can be removed and installed in the new head

6 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Cylinder Head and Parts

7 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only This cast aluminum head has four-valve combustion chambers Cylinder Head Construction

8 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Cylinder Head Construction This cast iron head has two-valve combustion chambers

9 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Valve Guide Construction  There are two basic types of valve guides:  integral valve guides  pressed-in valve guides

10 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Integral Valve Guide  Part of the cylinder head casting  Simply a hole machined through the cylinder head  Very common because of its low production cost

11 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Pressed-In Valve Guide  Separate sleeve forced into a hole machined in the cylinder head  Made of cast iron or bronze  During repair, a worn guide can be pressed out and a new guide can be quickly pressed in

12 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Valve Seat Construction  Valve seats can be integral or pressed-in  Integral valve seat  machined portion of the cylinder head casting  Pressed-in valve seat  separate part that is forced into a recess cut into the head  commonly used in aluminum heads

13 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Valve Seats and Guides

14 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Valve Seat Angle  Angle formed by the face of the seat  Most engines use a 45º angle  Some high-performance engines use seat angles of 30º

15 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Valve Seat Angle An interference angle increases sealing pressure and speeds seating

16 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Diesel Prechamber Cup  Pressed into the cylinder head of some diesel engines  Holes are machined into the deck  Prechambers are force-fit into these holes  Each prechamber forms an enclosure around the tip of an injector and glow plug

17 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Area is heated by the glow plug for better cold starting Diesel Prechamber Cup

18 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Stratified Charge Chamber  Fits into the cylinder head casting to form an auxiliary chamber  Uses a rich fuel mixture in the auxiliary chamber to ignite a lean mixture in the main combustion chamber

19 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Stratified Charge Chamber

20 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  The valve train controls the opening and closing of the cylinder head ports  Construction will vary with engine design  To be able to work on any type of valve train, you must understand these differences

21 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Valve Construction  Automotive engines commonly use poppet valves  Some valve stems are chrome plated to better resist wear  Grooves are cut into the valve stem tops for the keepers

22 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Valve Construction A. Polished intake valve B. Stock exhaust valve C. Hollow exhaust valve is filled with sodium for cooling

23 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Valve Face Angle  Angle formed between the valve face and valve head  Normal valve face angles are 45º and 30º

24 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Sodium-Filled Valves  Used when extra valve cooling action is needed  During operation, the sodium inside the hollow valve melts, becoming a liquid  This liquid is used to cool the valve

25 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Sodium-Filled Valves  When the valve is opened, the sodium splashes down into the head and collects heat  When the valve is closed, the sodium splashes up into the stem  Heat transfers out of the sodium and into the stem, valve guide, and engine coolant

26 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Stellite Valve Stellite coating on its face retards wear and allows the use of unleaded gasoline

27 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Valve Seal Construction  Valve seals come in two basic types:  umbrella valve seals  O-ring valve seals

28 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  Shaped like a cup  Made of neoprene rubber or plastic  Slides down over the valve stem before the spring and retainer  Covers the small clearance between the valve stem and guide  Keeps oil from being drawn into the cylinder head port and combustion chamber Umbrella Valve Seal

29 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Umbrella Valve Seal A. Synthetic rubber seal with plastic shedder insert B. All synthetic rubber seal C. Plastic valve seal

30 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only O-Ring Valve Seal  Small round seal that fits into an extra groove cut in the valve stem  Seals the gap between the retainer and valve stem  Stops oil from flowing through the retainer, down the stem, and into the guide  Fits onto the valve stem after the spring and retainer

31 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only O-Ring Valve Seal

32 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Nylon Shedder Used to limit the amount of oil that splashes on the valve stem

33 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Valve Spring Construction This dual coil spring is designed to increase spring pressure

34 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Valve Spring Terminology  Spring tension  stiffness of a valve spring  service manual will give the tension in pounds or kilograms for specific compressed lengths  Spring free length  length of the spring when removed from the engine

35 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Valve Spring Shim  Very thin, accurately machined washer used to increase spring tension  When a shim is placed under a spring, the open and closed lengths of the spring are reduced  Provides a means of restoring full spring pressure without spring replacement

36 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Valve Retainers and Keepers Used to lock the valve spring onto the valve

37 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Valve Spring Seat  Cup-shaped washer installed between the cylinder head and the bottom of the valve spring  Provides a pocket to hold the bottom of the valve spring

38 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  Turn the valves to prevent carbon buildup and hot spots on the valve faces  May be located under or on top of the valve spring  Commonly used on exhaust valves, which are exposed to more heat than intake valves Valve Rotators

39 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only This engine uses a valve rotator for each exhaust valve Valve Rotators

40 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only This engine uses a valve rotator for each valve Valve Rotators

41 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Valve Stem Cap  May be placed over the end of the valve stem  Helps prevent stem and rocker arm wear  Free to turn on the valve stem  Serves as a bearing that reduces friction  May be used to adjust clearance in the valve train

42 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Camshaft  Controls when the valves open and close  May be driven by gears, a chain, or a belt  There may be one or two camshafts per cylinder head

43 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only In dual overhead cam engines, there are two camshafts per cylinder head Camshaft

44 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Cam Lobes  Precision-machined and polished surfaces on the camshaft  Variations in lobe shape control:  when each valve opens in relation to piston position  how long each valve stays open  how far each valve opens

45 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Cam Lobe

46 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Camshaft Terminology  Camshaft lift  how far the valve opens  Camshaft duration  how long the valve stays open  Valve timing  valve opening and closing in relation to the position of the pistons

47 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Camshaft Terminology  Variable valve timing  engine can alter when the valves open with engine speed  Valve overlap  time when both the intake and exhaust valves in the same cylinder are open  used to improve the movement of gases through the engine

48 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Valve Timing

49 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Dual Cam Lobes  Some camshafts are machined with dual cam lobes that have two different profile shapes  one lobe is designed for low-speed efficiency while the other lobe is designed for high-speed efficiency  The ECM operates a solenoid valve that controls oil flow to shift the rocker arms from one lobe profile to the other

50 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Hollow Camshafts  Have their lobes pressed onto the shaft  To lock the lobes in place, an oversize steel ball is forced down through the center of the hollow shaft  Produces a lightweight camshaft

51 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Camshaft Thrust Plate  Used to limit camshaft end play  Bolts to the front of the block or cylinder head  When the drive gear or sprocket is bolted in place, the thrust plate sets up a predetermined camshaft end play

52 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Cam Bearings One- or two-piece inserts that are installed in the block or cylinder head

53 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Cam Housing and Cover  Cam housing  casting that bolts to the top of the cylinder head to hold the camshaft  used in some overhead cam engines  Cam cover  lid over the top of the cam housing  prevents valve train oil spray from leaking out of the engine

54 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Valve Lifters Ride on the camshaft lobes and transfer motion to the other parts of the valve train

55 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Hydraulic Lifters Operate quietly by maintaining zero valve clearance

56 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Hydraulic Lifters The lifter adjusts automatically with temperature changes and part wear

57 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Hydraulic Lifter Operation  Charging cycle  when the valve closes, oil rushes into the lifter, pushing up on the internal disc or plunger to maintain zero clearance  Leak-down cycle  when the cam acts on the lifter, oil is trapped in the lifter by a check valve  lifter acts as a solid unit to push the valve open

58 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Hydraulic Lifter Operation

59 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Mechanical Lifters Transfer cam lobe action to the push rod

60 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Mechanical Lifters  Do not contain oil  Periodic adjustment is required  Adjustment is normally provided at the rocker arm  Small valve train clearance needed causes clattering or clicking noise when the valves open and close

61 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Roller Lifters A small roller rides on the camshaft lobe to reduce friction

62 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only OHC Follower Fits between the camshaft and valve

63 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only OHC Follower Components

64 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Push Rods  Metal tubes or rods with specially formed ends  Used in cam-in-block engines to transfer motion from the lifters to the rocker arms

65 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Push Rods An inline engine using a pivot ball to hold the rocker arm

66 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Push Rod Guide Plates Used to limit side movement of the push rods

67 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Rocker Arms Transfer valve train motion to the valve stem tips

68 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Pivot Balls (Stands) Used to hold the rocker arm in place over the valve

69 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Adjustable Rocker Arms  Used to change the valve train clearance  Either a screw is provided on the rocker arm or the rocker arm pivot point can be changed  Must be used with mechanical lifters

70 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Nonadjustable Rocker Arms  Have no means of changing valve clearance  Used only with some hydraulic lifters  The rocker arm assembly is tightened to a specified torque  presets the lifter plunger halfway in its travel  Push rod length can be changed for clearance adjustments

71 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only

72 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Intake Manifold  Holds the throttle body and has passages, called runners, going to each cylinder head port  May contain water jackets for cooling  Cast of iron, aluminum, or plastic

73 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Manifold Runners  Carry either the air-fuel mixture or air to the cylinder head ports  Exhaust passages warm the manifold

74 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only “Ram Manifold” Assembly Takes the place of a traditional intake manifold

75 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Composite Manifolds  Intake manifolds can be made of glass- filled nylon or plastic  Weighs half as much as aluminum  Plastic runners are smoother than metal on the inside, improving airflow  Brass thread inserts are molded into the plastic, allowing parts to be bolted to the manifold

76 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Flame Arrester  Located between the air filter and the engine intake manifold  Prevents backfire damage to the air filter  Made of metal mesh to prevent the flame of a backfire from entering the air filter housing

77 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Variable Induction System  Provides increased engine efficiency and performance  Uses two sets of intake runners controlled by butterfly valves  Butterfly valves are computer-controlled

78 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Variable Induction System  At low engine speeds, the system uses the longer intake runners, improving low-end torque  When a specific engine speed is reached, the computer opens the butterfly valves over the shorter intake runners  Airflow is increased for added power

79 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only

80 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Exhaust Manifold  Routes burned exhaust gases from the cylinder head exhaust port to the exhaust pipe  Made of cast iron or steel tubing

81 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Manifolds Intake and exhaust manifolds with their related components


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