Gravely 424 - Fuel System

FUEL
SYSTEM
CARBURETON
Carburetors
are adjusted
in
the factory
and under normal conditions require no
further adiustment. If, how-
ever,
one of
the
following crnditions
exist,
readjustment of
the
carburetor
may be needed.
Maximum
power
and eficieucy
are
possible
only
with
proper
carburetion. Improper carburetor adjustment
can
lead
to overheating, fouled spark
plug,
excessive
valve wear
and other
problems.
Do not
neglect
carbu-
retor
if
any
of the above
problems
persist.
The following adjustment
procedure
is for
the
standard side draft
carburetors.
STEP 1-
Stop
engine and
carefully
turn
Main FueI
and
Idle Fuel Needle
adjusting screws
arll
the
wly
in
(clockwise
direction)
until
they
bottom
-
DO
NOT FORCE
SCREWS as this
will damage needle
valves.
STEP
2
-
For
preliminary
adjustment,
turn Main Fuel screw 2
turns
in
counterclockwise direction, trrrn
Idte
fuel
screw
1Yl
turns
in
counterclockwise direction.
STEP 3
-
Start engine and operate at normal
spoed until
normal
operating temperatures are
reached.
STE? 4
-
Main
Fuel Adjustment
-
lVith engine operating at
full tlrottle and full load, turn Main
Fuel
Needle
in
(clockwise)
until
en$ne slows
down
(lean),
note
lrcsition
of screw, then turn
needle
out
{counter-
clockwise) until
engine regains
speed and then again
slows down
(overrich).
Turn needle back
in
until it is
trrosilioned
halfway
between
lean and overrich
settings.
If adjusted
properly,
the engine
should
accelerate smoothly
and operate with
steady
governor
action.
STE? 5
-
Idle
f'uel Adiustment
-
Operate
engine at
idle
speed of
about 1000 RPM
(adjust
Idle
Speed
screw
until
thb speed is
attained
-
check with tachometer). Turn
IdIe
Fuel Needle in
(clockwise)
until
engine slows
down and idles
rough then turn screw
out until engine speeds up and
idles
smoothly
at
the desired
idle speed.
STE?
6
-
Final
Adjustment
-
Since
main fuel and idle fuel adjustment have
some afiect on
each other,
recheck
engine
and nrake ffnal adjustments
as necessary to achieve smoothest operation.
NOTE: If
the
preceding
steps do not
remedy
problems
attributed
to carburetor, carburetor
reconditioning
may
be necessary.
Carburetor
Reconditioning
Service
di&eulties
with
fuel
systems usually originate from
improper
carburetor
adjustmeats or
dirt,
gqm
or
varnish in components"
It
will be necessary
to
completely &sassemble carburetor to clean throughly.
Normally
only
pre-season
cleaning
will be
required; however,
the
frequency
of cleaning will
depend
utrron use and
operating conditions.
AII
parts
should
be cleaned
in
a solvent.
Gum is easily
removed with an
alcohol oi
a@tone
solvent. Be sure
any
carbon
deposits
are
removed
from
bore,
especially
where throttle
plate
seats in casting. Blow out all
pas-
sages with compressed
air. Replace
all worn
and
damaged
parts.
Always
use
new
gaskets.
Carburetor
repair
kits are
available for
carburetors.
Th"y include
the bowl nut
gasket,
bowl
ring
gasket,
foat
pin,
bowl baffie
gasket
and
fuel inlet needle and
seat.
CONDITION POSSISLE
CAUSE/PROBABLE NEMEDY
A. Black, sooty exhaust smoke, engine
sluggish. A.
Mixture
too rich
-
readiust main
fuel
needle.
B. Engine misses
and backffres
at high
speed.
B.
Mixture too lean
-
readjust
main
luel
needle.
C. Engine starts, sputters and dies under cold
weather starting.
C. Mixture too lean
-
turn
main
fuel
adjustment
Ya
turn
counterclockwise.
D. Engine
runs rough
or
stalls at idle
speed.
D. Improper
idle adjustment
-
readjust
idle fuel
needle.