ASVAB Automotive Information Practice Test 76174 Results

Your Results Global Average
Questions 5 5
Correct 0 2.97
Score 0% 59%

Review

1

The stoichiometric ratio is approximately:

70% Answer Correctly

14.7

14.7:1

1:1

1:14.7


Solution

The stoichiometric ratio defines the proper ratio of air to fuel necessary so that an engine burns all fuel with no excess air. For gasoline fuel, the stoichiometric ratio is about 14.7:1 or for every one gram of fuel, 14.7 grams of air are required. Too much air results in a lean air-fuel mixture that burns more slowly and hotter while too much fuel results in a rich mixture that burns quicker and cooler.


2

What is the function of the alternator?

59% Answer Correctly

charges the battery when the car is not running

replaces the electrical energy that the car draws from the battery

provides AC power for the car's electrical components

converts motion from the wheels into DC power


Solution

An automobile's electrical system runs on DC power and the bulk of that power is supplied by the battery. The alternator converts the motion of the rotor into AC power which is then fed through the rectifier to convert it to DC power that both the car and the battery can use.


3

The spark plugs fire a few extra degrees before top dead center when the engine is running faster. In this case the engine's timing is:

62% Answer Correctly

retarded

synchronous

asynchronous

advanced


Solution

Ignition timing defines the point in time at the end of the compression stroke that the spark plug fires. Measured in number of degrees before top dead center (BTDC), the exact point that the spark plugs initiate combustion varies depending on the speed of the engine. The timing is advanced (the spark plugs fire a few more degrees BTDC) when the engine is running faster and retarded when it's running slower.


4

Piston rings are responsible for which of the following?

50% Answer Correctly

regulating oil distribution inside the cylinder

connecting the piston to the spark plug

connecting the piston to the camshaft

containing combustion


Solution

Cylinders act as a guide for the pistons that translate the heat energy of combustion into the mechanical energy necessary to move a vehicle. Piston rings seal the piston to the cylinder to contain combustion gases and also regulate the oil distribution between the piston and cylinder wall. A cylinder head closes in the top of the cylinder forming the combustion chamber which is sealed by a head gasket (head). The head provides space for air and fuel intake valves, exhaust valves, and mounts for spark plugs and fuel injectors.


5

The firing order of the cylinders in an engine can be found by:

59% Answer Correctly

observing the order in which the intake valves open

observing the direction in which the intake valves open

reversing the cylinder number

identifying the cylinder number


Solution

The firing order of the cylinders in an engine is different than the cynlinder numbers and can be found by observing the order in which the intake valves open.