ASVAB Practice Test – Automotive Information (Multiple Choice)

It takes about 15 pounds of air to completely burn 1 pound of gasoline so the air-fuel ratio for normal gasoline engine operation is 15: 1.

Valve lifters run on the camshaft and are made to move vertically by the action of the rotating cam. Valve lifters connect to pushrods that connect to rockers which reverse the direction of the lifter movement to press the valves downwards to open them.

A reciprocating engine is an engine whose crankshaft is turned by pistons moving up and down in a cylinder.

The correct order of cycling sequence for a four-stroke engine is: Intake stroke, Compression stroke, Power stroke, Exhaust stroke which makes Intake stroke, Compression stroke, Exhaust stroke the correct answer.

The four-stroke cycle produces pulses that can cause vibrations in the crankshaft. The flywheel reduces pulsating from the crankshaft.

In engine lubrication, oil remains in the oil pan until the engine is turned on. It then gets sucked up the pickup tube by the oil pump and pressurized. This pressure is moderated by the pressure relief valve and the oil is fed through the oil filter into the engine to lubricate it.

Aluminum parts should be cleaned in a cold tank because a hot tank destroys nonferrous metals like aluminum.

Four common cylinder arrangements are in-line, V, opposed, and radial.

The timing belt synchronizes the camshaft and the crankshaft. Maintaining proper synchronization between the rotation of the camshaft and the rotation of the crankshaft is critical to ensure that the engine’s valves open and close at the proper times during each cylinder’s intake and exhaust strokes.

In-line cylinder arrangements number cylinders sequentially (1, 2, 3, …) front to rear.

Four common cylinder arrangements are in-line, V, opposed, and radial.

The solenoid controls the circuit between the battery and the starter motor. When a car’s ignition switch is activated the starter solenoid receives the electric signal from the ignition which causes it to close a pair of heavy contacts enabling the flow of electric current from the battery to the starter motor.

The drive train is the system that connects the transmission with the driving axles of an automobile.

The distributor delivers voltage from the ignition coil to the cylinders. The distributor is responsible for helping the coil develop high voltage and then getting that high voltage to the cylinder combustion chambers via the spark plugs at the correct time to properly ignite the air-fuel mixture.

The four-stroke cycle produces pulses that can cause vibrations in the crankshaft. The flywheel reduces pulsating from the crankshaft.

The ignition coil steps up the 12 volts available from the battery or alternator to a voltage of 30,000 or more volts at the spark plug. Converting a lower voltage input into a higher voltage output makes the ignition coil a step-up transformer.

The cylinder head closes the top of the cylinder forming the combustion chamber. It sits just above the cylinders on top of the cylinder block forming a joint that’s sealed by the head gasket.

It takes about 15 pounds of air to completely burn 1 pound of gasoline so the air-fuel ratio for normal gasoline engine operation is 15: 1.

The correct order of cycling sequence for a four-stroke engine is: Intake stroke, Compression stroke, Power stroke, Exhaust stroke which makes Compression stroke, Power stroke, Exhaust stroke the correct answer.

The slip joint allows the transmission to deliver power over rough terrain. Because the rear axle moves up and down on the suspension when the vehicle is traversing rough terrain, the distance between the transmission and the rear axle frequently changes. For this reason the drive shaft is not anchored to the rear axle and a slip joint is used between them. The slip joint moves in and out on the transmission shaft to allow for change of distance between the transmission and rear axle over rough terrain.

The exhaust system of an automobile consists of an exhaust manifold that attaches to the cylinder head and collects burned gases from the engine, a catalytic converter that converts pollutants in the gases into less harmful emissions, a muffler that quiets the noise resulting from engine exhaust, and an exhaust pipe that links system components together.

The distributor delivers voltage from the ignition coil to the cylinders. The distributor is responsible for helping the coil develop high voltage and then getting that high voltage to the cylinder combustion chambers via the spark plugs at the correct time to properly ignite the air-fuel mixture.

An automotive battery produces direct current for use by automotive systems.

A head gasket is a gasket that sits between the engine block and cylinder heads to seal the cylinders to ensure maximum compression and avoid leakage of coolant or engine oil into the cylinders.

A reciprocating engine is an engine whose crankshaft is turned by pistons moving up and down in a cylinder.

Fuel injection has replaced the carburetor as the primary automobile fuel delivery system. The main difference between the fuel injector and the carburetor is that fuel injection atomizes the fuel by forcibly pumping it through a small nozzle under high pressure while a carburetor relies on suction to draw fuel into an accelerated intake air stream.

Engine cycling is the number of strokes that an engine makes to generate power. The characteristics of a two-stroke engine include: fire once every revolution, used in small engines, does not have valves, combine the intake and compression strokes, combine the combustion and exhaust strokes. The characteristics of a four-stroke engine include: fire once every other revolution, used in larger engines, have separate strokes for intake and compression, have separate strokes for combustion and exhaust.

An overcooled engine is less efficient. During the power stroke, combustion heat pushes down the piston. If too much of this heat is lost to the cooling system, the fuel might not combust completely and contaminate the engine’s lubricating oil diminishing its lubricating ability. Incomplete combustion of fuel also negatively affects the engine’s fuel efficiency and power output.

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