Question 1

Why are valve rotators used?&#10;A) Distribute heat across the valves evenly.&#10;B) Keep valve spring tension constant.&#10;C) Minimize carbon buildup on the valve seat and promote even wear.&#10;D) Prevent valve/piston crown collisions.

Accepted Answer

Valve rotators are designed to minimize carbon buildup on the valve seat and promote even wear, which helps to maintain proper engine performance and efficiency. They do not help distribute heat, keep valve spring tension constant, or prevent valve/piston crown collisions.

Question 2

What types of lifters can be used in cylinder block-mounted camshafts?&#10;A) Solid, roller and hydraulic.&#10;B) Direct-actuated and roller.&#10;C) Only hydraulic.&#10;D) Solid, direct-actuated and roller.

Accepted Answer

Cylinder block-mounted camshafts can use solid, roller and hydraulic lifters. Solid lifters are used in high-performance engines due to their durability and ability to handle high valve lift. Roller lifters reduce friction and improve engine efficiency. Hydraulic lifters offer a quieter operation and require less maintenance compared to solid lifters. Therefore, the best choice is A as it offers a variety of options for different engine needs.

Question 3

What are the two gear tooth designs are used for timing gears?&#10;A) Helical and spur.&#10;B) Hypoid and planetary.&#10;C) Spiral and worm.&#10;D) Toothed and friction.

Accepted Answer

Helical and spur gear tooth designs are commonly used as timing gears. Spur gears are simple and cost-effective, while helical gears run more smoothly and quietly due to their angled teeth.

Question 4

What is the smallest radial dimension of a cam on camshaft known as?&#10;A) Cam profile.&#10;B) Base lift radius (BLR).&#10;C) Inner base circle (IBC).&#10;D) Cam bottom.

Accepted Answer

The smallest radial dimension of a cam on a camshaft is known as the Inner Base Circle (IBC). This is the circle from which the cam profile starts to rise as it rotates. Choice A, Cam profile, refers to the shape of the cam itself, which includes the IBC. Choice B, Base lift radius (BLR), refers to the distance from the center of the camshaft to the highest point on the cam lobe, which is not necessarily the same as the IBC. Choice D, Cam bottom, is not a commonly used term in camshaft design.

Question 5

How many revolutions does a camshaft turn through a complete four-stroke cycle?&#10;A) Four&#10;B) Three&#10;C) Two&#10;D) One

Accepted Answer

In a four-stroke engine, the camshaft turns one revolution for every two revolutions of the crankshaft. This is because the four strokes (intake, compression, power, and exhaust) require two complete revolutions of the crankshaft to complete, while the camshaft, which operates the intake and exhaust valves, only needs to complete one cycle for these four strokes.

Question 6

What advantages do pushtubes have over pushrods?&#10;A) They are much stronger.&#10;B) They provide high strength with less weight.&#10;C) They can be made from cheaper materials.&#10;D) They work better when rod length is short.

Accepted Answer

Pushrods are typically made of steel, whereas pushtubes can be made from lightweight materials like carbon fiber, resulting in high strength with less weight. This can provide advantages in aircraft and other weight-sensitive applications. While pushtubes also have the potential to be stronger than pushrods, this isn't always necessary, and may not be a significant advantage. Cheaper materials may also be an advantage in some applications, but this isn't a guaranteed benefit of pushtubes. The advantage of working better with short rod lengths isn't a factor in comparison between pushrods and pushtubes, as both can be designed to work effectively with short lengths.

Question 7

What is a typical geartrain backlash specification?&#10;A) 0.002mm (0.00007in)&#10;B) 1.0mm (0.039in)&#10;C) 6.0mm (0.24in)&#10;D) 0.200mm (0.008in)

Accepted Answer

A typical geartrain backlash specification ranges from 0.08mm to 0.25mm (0.003in to 0.01in), but out of the given options only D falls within this range. Therefore, option D with a backlash specification of 0.200mm (0.008in) is the best choice.

Question 8

What results from increasing rocker ratio?&#10;A) Decrease in output travel at the pallet end of the rocker arm.&#10;B) Decrease in mechanical advantage.&#10;C) Increase the amount of pushrod travel.&#10;D) Increase the output travel at the pallet end of the rocker arm.

Accepted Answer

Increasing the rocker ratio will increase the output travel at the pallet end of the rocker arm, which means that the valve will open more with the same amount of lift from the camshaft. This can improve engine performance and power output.

Question 9

Technician A states block mounted cams convert rotary motion into linear motion of the followers. Technician B states overhead cams convert rotary motion into rotary motion of the rocker arms..&#10;A) Technician A only.&#10;B) Technician B only.&#10;C) Both A and B.&#10;D) Neither A nor B.

Accepted Answer

Both statements are correct. Technician A is correct in stating that block mounted cams convert rotary motion into linear motion of the followers, which is a fundamental principle of camshaft operation in many internal combustion engines. Technician B is also correct in stating that overhead cams convert rotary motion into rotary motion of the rocker arms, which then act on the valves. This is a common configuration in overhead camshaft engines, where the camshaft is located above the cylinder heads.

Question 10

What is valve lash?&#10;A) Valve noise caused by carbon buildup.&#10;B) Delayed valve spring reaction time under high engine rpm.&#10;C) the ratio of valve head diameter to valve stem length.&#10;D) A specified clearance between the rocker pallet end and valve stem top.

Accepted Answer

Valve lash refers to the specified clearance between the rocker pallet end and valve stem top. This clearance must be set correctly to ensure proper valve lift and prevent valve damage.

Question 11

What are fire rings designed to do as a cylinder head is torqued?&#10;A) Stay rigid.&#10;B) Hold their shape for repeated use.&#10;C) Temporarily protect the cylinder bore flange until the head gasket makes a seal.&#10;D) Deform to create the best possible seal.

Accepted Answer

The answer of What are fire rings designed to do...

Question 12

What type of cylinder head is always used on an engine with a aluminum block?&#10;A) Aluminum or cast iron.&#10;B) Aluminum.&#10;C) Space age plastic.&#10;D) Cast iron.

Accepted Answer

The answer of What type of cylinder head is always...

Question 13

In order to avoid damage, what component should be removed prior to removing a cylinder head?&#10;A) Spark plugs.&#10;B) Fuel injectors.&#10;C) Overhead cams.&#10;D) Glow plugs.

Accepted Answer

The answer of In order to avoid damage, what component...

Question 14

When are exhaust valves exposed to the most heat?&#10;A) When closed at the end of the power stroke.&#10;B) When opened at the end of the power stroke.&#10;C) Immediately after the engine is shut off.&#10;D) During the exhaust stroke.

Accepted Answer

The answer of When are exhaust valves exposed to the...

Question 15

Technician A states hydraulic lifters are suitable for camshaft designs where the lifter is not required to actuate the pump action of unit injectors. Technician B states hydraulic lifters are not suitable for OHC designs.

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

Accepted Answer

The answer of Technician A states hydraulic lifters are suitable...

Question 16

How do you create a valve polar diagram for a diesel engine?&#10;A) Refer to the manufacturers service literature for valve event information.&#10;B) Using data from the PCM.&#10;C) Observe valve events of a running engine using a strobe.&#10;D) Observe, record and record, the valve and injector events through the entire four-stroke cycle.

Accepted Answer

The answer of How do you create a valve polar...

Question 17

How do you measure camshaft endplay?&#10;A) The installed camshaft is gently forced backward then forward measured with a dial indicator.&#10;B) The installed camshaft is rotated and measured with a dial indicator.&#10;C) Install the camshaft and start the engine, measure any backward or forward movement with a dial indicator.&#10;D) Using the camshaft endplay sensor data from the PCM.

Accepted Answer

The answer of How do you measure camshaft endplay?&#10;A) The...

Question 18

What should be avoided when adjusting valves.&#10;A) Adjusting the valves in engine firing sequence.&#10;B) Adjusting the valves when the engine is cold.&#10;C) Adjusting the valves too tight.&#10;D) Adjusting valves with valve bridges.

Accepted Answer

The answer of What should be avoided when adjusting valves.&#10;A)...

Question 19

What is valve margin?&#10;A) The dimension between the valve seat and the flat face of the valve head mushroom.&#10;B) The ratio of the total valve head surface to seat surface.&#10;C) The outer diameter of the valve head.&#10;D) The length of the valve stem.

Accepted Answer

The answer of What is valve margin?&#10;A) The dimension between...

Question 20

How should a typical timing gear be installed onto a shaft?&#10;A) Press the gear on with a air-over-hydraulic press.&#10;B) Cool the shaft as much as possible.&#10;C) Heat the gear to the manufacturers specified temperature.&#10;D) Heat the shaft and gear to manufacturers specified temperature.

Accepted Answer

The answer of How should a typical timing gear be...

Deck 4: Timing Geartrain and Cylinder Head Assemblies