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Bowl
Vent
FUEL
_
CARBURETION
-
EXHAUST
II
justing screw port.
Adiusting
the idle
mixture
screw
controls
lhe
omount
of
mixture
dis-
chorged
lnto the
monifold.
Turning
the idle
screw
toword its seot
reduces
the
omount
of
mixture;
turning
the
screw
out
increoses
the
omount
of
mix-
ture
odmitted
to the
monifold
The
idle port
is
slot
shoPed
ond
os
the throttle
volves
ore
opened,
more
of the idle porl is
uncovered
to
the
low
pressure
in the
monifold
which
couses
o
colibroted increose
in
the
omount
of idle
mixture
to
flow
to
the
monifold.
The
idle iet,
by-Poss,
economizer,
idle
bleed,
ond idle port
hole,
os well
os
the
bores
of
the
corburetor
ore
oll
metering
points
ond
must
be
{ree
from
dirt
ond
corbon
dePosits.
Re-
strictions
will
couse
poor low
speed
performonce.
Worn
or
domoged
idle
odiusting
screws
should
be
reploced.
Vopor
vent
holes
drilled into
the
body flonge
obove
the throttle
plotes
oid
in
quick hot
engine storting.
They
prevent
fuel
vopors
from
occumulot-
ing in the
bores
of the
corburetor
by
ollowing them
to
escope
to
the
ot-
mosphere,
High Speed
Circuit
Fuel
for
most
port throttle ond
oll
full
throttle operotion
is
supplied
through the high
speed circuit.
The position
of
the
metering
rods
in the
metering
rod
iets, controls
the
By-Poss
Econom
izer
ldle
Bleed
Low Speed
Jet'
ldle
Porl
,/
ldle
Adiustment
Screw
Fuel
Slroiner
Needle
ond
Seoi
Assembly
I
Floot
Assembly
FIGURE
2l
-
Floot
Circuit
costings must
seol
tightly
ot
the
vori-
ous
possoge connections
ond
between
the bowl ond the
corburetor bore.
Al-
woys
use
o
new bowl
gosket
to
ossure
this
positive
seol
to
prevent stolling
or
errotic
idle ond low
speed
perform-
Low Speed
Circuit
Fuel
for
idle ond
eorly port
throt-
tle
mixiures is metered
through the
low
speed
circuit.
Gosoline enters
the idle
wells
through
the
metering
rod
lets.
The
low speed iets
meter
the
fuel ot
the
lower end
of
the tube.
Fuel
flows
uP
through
the tube into the
possoge
in
the bowl
cover where
oir,
metered
through
the
by-poss, mixes
with
the
fuel,
Both
oir
ond fuel then
poss
through
the
economizer,
and
move
downword
in the
possoge
where
od-
ditionol
oir,
metered
by
the idle
bleed,
mixes
with the fuel
to
ottoin
on
ideol
combustible mixture.
This
idle
mix-
ture
is
then
dischorged
into
the
moni-
{old
below
the throttle
plotes
through
the
idle port
opening ond the
idle
od-
Economizer
low
Speed
Jet
ldle
Adiuslment
Screw Port
ldle
Adiustment
Screw Port
)
]I
(..or
ldle
Port
(Slot)
ldle
Bleed
FIGURE
22-Low
Speed Circuit
\
I
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