SGE chapter 5

An absolute ____ is any area completely free of air or atmospheric pressure

Vacuum

when closed, the choke provides a ___ air-fuel mixture needed during the starting of a cold engine

richer

Three basic functions of governors:

1. Maintain a speed selected by the operator which is within range of the governor 2.Prevent overspeeding that may cause engine damage 3. limit both high and low speeds

Three types of governors

1. air vane (pneumatic) 2. centrifugal (mechanical) 3. vacuum

gasoline must be ___ by the carburetor

vaporized

a constant speed governor should have a _____ sensitivity to function well

high

normal air-fuel mixture ration:

15 parts air to 1 part fuel

The primer on a float type carburetor pumps:

Air pressure into the float bowl forcing fuel up the nozzle

explain how a choke provides a richer air-fuel mixture

Because it leads to less air entering the combustion chamber, meaning a higher concentration of fuel is in there

a carburetor's primary function is to mix proper proportions of ___ and ___ to operate the engine

Fuel, air

Name four factors that enhance the vaporization of fuel before it enters the cylinder

Temperature Pressure TWO MORE?

Venturi principle

a restriction in a passage which causes air to move faster (increases velocity)

the ___ )) stores fuel for use during rapid acceleration

acceleration well

explain how a carburetor works

air enters the carburetor, misses with fuel in proper proportion, and the mixture flows into the combustion chamber

On an air vane governor, controlling speed is accomplished by balancing ____ pressure with ____ ____

air, spring pressure

As soon as the intake valve opens or the intake port is uncovered in a gas engine, ___ ___ forces air through the carburetor and manifold to fill that vacuum

atmospheric pressure

how is air pressure above the fuel in the float bowl and the air pressure entering the carburetor equalized

by a vent in the float bowl, which assures a continuous, free flow of fuel

the carburetor ___ is a round disc mounted on a shaft located at the intake end of the carburetor

choke

which carburetor can provide larger volumes of fuel for high speed and power requirements

downdraft

Which type of air cleaner passes the airstream through treated paper, felt, fiber, or flocked screen?

dry-type air cleaner

Diaphragm carburetors are operated by the _____ _____

flexible diaghragm

the air vane governor is operated by the stream of air created by the ____ cooling fins

flywheel

the the engine speeds up and slow down repeatedly under a constant load condition, this is known as

hunting

what is the purpose of the carburetor float

maintain a constant level of fuel in the float bowl

as fuel is used from the float bowl, and float lowers and unseats a ___ valve which lets fuel enter the bowl

needle

Three types of air cleaners widely used in small gas engines

oil bath oil-whetted dry types

which type of air cleaner element can be used again by washing it in cleaning solvent

oil-wetted air cleaner

the economizer circuit is designed to retard fuel flow to the engine at

part throttle

the percent of engine speed change required to produce a corrective movement of the fuel control mechanism is called

sensativity

if an engine is designed to run at a constant speed, the speed is adjusted with thee governor ____

spring

ability of a governor to maintain a preset speed without fluctuating is called

stability

Explain how the throttle valve controls engine speed and power

throttle valve - regulates amount of air-fuel mixture that enters the cylinder and is often linked to a governer, which is connected for a speed control. this allows for the throttle valve to open more or less mixture to maintain a given speed

explain the main purpose of the throttle valve

to regulate the amount of the air-fuel mixture entering the cylinders

T & F; air-fuel mixture requirements vary, depending upon various operating conditions

true

T& F; a Carburetor is a device that is operated by pressure differences

true

in which carburetor must air velocity be highest

updraft

in a diaphragm tpe carburetor on two cycle engines, the fuel is drawn into the crankcase during the...

upstroke of the piston

type of governor usually used on farm and industrial engines

vacuum