ASVAB Auto and Shop Practice Questions

1.  What is the primary difference between fuel injection and carburetors? 

a. Fuel injection relies on suction and pressure
b. Fuel injection atomizes fuel
c. Carburetors atomize fuel
d. Carburetors rely on suction

2. Internal combustion engines use a fuel-air mixture that is designed to burn all of the fuel.  The perfect fuel-air ratio is never achieved because: 

a. The measurement is too precise.
b. The combustion cycle is too fast.
c. The combustion cycle is too slow
d. Anti-pollution and performance tuning prevents the exact mixture.

3. Which type of pipe cutter would you use for a copper pipe? 

a. Cutters that look like gardening shears
b. Cutters with a sharp wheel
c. A hacksaw
d. None of the above

4. What is a tie rod?

a. A rod that is fastened to the piston
b. A rod that connects the clutch to the pedal
c. A rod that is connected to the universal joint
d. None of the above.

5. What is the purpose of the crankshaft?

a. Converting the up-and-down motion of the tie rods and pistons into rotational movement.
b. Converting the rotational movement of the pistons and tie rods into up and down movement.
c. Connecting the tie rods and piston
d. Connecting the tie rods to the transmission

6. What is torque?

a. Rotation
b. Pressure
c. Up and down motion
d. A twisting force that causes rotation

7. Consider two gears, one that is twice as large as the other.  How fast will the smaller gear rotate?

a. One-quarter as fast as the larger gear
b. Twice as fast as the larger gear
c. 50% faster than the larger gear
d. None of the above

8. One gear has 80 teeth and the other has 20 teeth. What is the gear ratio? 

a. 2:1
b. 3:1
c. 4:1
d. 2:1

9. Why does a vehicle overheat more on hot days than on cold days? 

a. The engine works harder and generates more heat.
b. The cooling fluid is hotter.
c. The air moving through the radiator isn’t sufficient to cool the fluid.
d. None of the above.

10. Why aren’t the wheels of a vehicle attached to the vehicle body directly? 

a. Wheels are attached to the vehicle body directly
b. The shock of hitting bumps would easily break the connection
c. Wheels are attached to the suspension system for comfort only
d.None of the above.

1. C
The primary difference between carburetors and fuel injection is that fuel injection atomizes the fuel by forcibly pumping it through a small nozzle under high pressure, while a carburetor relies on suction created by intake air rushing through a venturi to draw the fuel into the airstream.

2. B
In theory the fuel-air mixture has just enough air to completely burn the available fuel. In practice this is never quite achieved, due primarily to the very short time available in an internal combustion engine for each combustion cycle. Most of the combustion process completes in approximately 4–5 milliseconds at an engine speed of 6000 rpm. This is the time that elapses from when the spark is fired until the burning of the fuel air mix is essentially complete after some 80 degrees of crankshaft rotation.

3. B
The best tool to cut a copper pipe is a pipe cutter with a sharp wheel and an adjustable claw.

4. A
The tie-rod is fastened to the piston and the crankshaft.

5.  A
The crankshaft converts the up and down motion of the pistons and tie rods into rotational movement.  The crankshaft is connected to gears that connect to the transmission.

6. D
Torque is a force that rotates or turns things.

7. B
The smaller bear will travel twice as fast as the larger gear.

8. C
The gear ratio will be 4:1.

9. C
Vehicles will tend to overheat more on hot days than on cold days because the air travelling through and around the radiator isn’t cold enough to cool the fluid.

10. B
The wheels are attached to the body of a vehicle through the suspension system, and not directly, because the shock of hitting bumps in the road would break the connection and/or structurally damage the vehicle.