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ENGINE FUEL AND EXHAUST SYSTEMS
STROMBERG CARBURETOR
3-51
choke stem bearings.
3. Float N
eedle Valve
and S
eat. Because
of
the wear that normally occurs in these parts
and the nec
essity
of having a tight seating
valve,
it is advisable to replace these parts if
the ca r bur et or has been used for considerable
mil
eage.
4. Vacu
um
Pow
er Piston
and By-Pass
Jet.
Make certain that the
surface
of the piston is
thoroughly clean. Do not use any
abrasive
ma-
terial for polishing the piston surface. Inspect
for wear or damage. Replace if
necessary.
Test
by-pass
jet for tight seating by sucking on the
upper end.
Replace
jet if doubtful.
5.
Main
Body.
Make certain the main body
is thoroughly clean and that all passages are
free
of
foreign
material. Check high speed and
idle air
bleeders
for correct sizes, using a drill
shank as a
gauge.
For drill sizes see Stromberg
Carburetor Calibrations, paragraph 3-l.
6.
Main Discharg e
J
ets
and Idl
e
Tub
es.
In-
sp
ect
tips of
main
discharge jets to make cer-
tain that they are not damaged, and that walls
are not
distorted
so as to
deform
the holes.
Test idle tubes by blowing or sucking to make
sure
that metering
holes
are
clear.
Inspect small
ends to make sure that
they
are not damaged
so as to deform the
metering
holes.
Replace any
parts whose condition appears
doubtful.
7.
Pump
Piston,
Che
ck
Valves
,
S
trainer,
Discharae
No
zzle.
Inspect pump piston leather
washer
for
cracks,
creases, turned edges, or
other damage.
T
est
relief valve in piston for
tight seating by blowing on lower end of pis-
ton
;
if valve is seating tightly it will not be
possible to blow through
it.
Test inlet check valve for tight seating by
su
cking
on lower end.
Inspect
outlet check valve
ball for rough surfaces.
Inspect inlet strainer for holes or other dam-
age.
Test
discharge
nozzle by sucking or blowing
to
make
sure
that all
holes are
clear.
Replac e
any
pa rt whose
condit ion
appears
doubt fu l.
8.
Th
r ot
tle
Val
v e
Bod
y
and I
dl e
N
eedle
Va
lv es.
Be
sure
that t
he idl
e
discharge hole
s,
the air
bleeders,
and
the barrels
of
t
he throttle
valve body are clean of all ca
rbon deposits.
A
comparatively
small amount of carbon in the
barrel may
have the
effect
of
decreasing
the
bore sufficiently to prevent
the throttle
valves
resting at the correct angle when closed. This
can have serious effects on
performance because
the
distance
from the throttle
valve,
when
closed, to
the
edge of
the
idle discharge hole
must be kept within close limits to the estab-
lished
dimension.
Check the size of the upper idle discharge
hole by
inserting the
shank of the cor rect size
drill.
This has the fu
rther advantage
of remov-
ing any
foreign matter that may
be obst r uct -
ing the hole. The
lower discharge
hole for the
idle
needle
val
ve
should
be checked
in
t
he same
manner. For drill siz
es
see Stromberg Carbu-
retor Calibrations
(par.
3-1 ) .
Inspect seats for idl
e
needle valves for scor-
ing or other
damage. If
ends of idl
e
n
eedle
val
ves
are
grooved
or
bent,
replace the
va
lves.
Check
wear of throttle
stem bearing.
There
should not
be more
than about .006"
play,
other-
wise air leaks will inte r fe r e with performance.
9. Throttle Va
lves, Throt
tle
L
ev er
and
Stem
A
ssembly.
See that
t
h r ottle val
ves
are not bent
and do not
have
burrs or sharp
edges.
Replace
if damaged.
Inspect throttle lever and stem assembly for
wear on bearing
surfaces.
Check pump rod holes
for wear and
also see
that
lever
is
not
loose on
stem. Replace if
necessary.
3-33 ASSEMBLY AND ADJUSTMENT OF
STROMBERG CARBURETOR
a. Assembly of Carburetor
In the
assembly
of
the carburetor,
use all new
gaskets and any additional new parts found to
be necessary du
ring inspection.
Figure
J
-87-Correct
Pos
ition
of Throttle Valves
1.
Install
throttle lever
and ste m assembly
in
throttle body. Insert
ea ch valve
through
the
stem
in
the same barrel from
which it was re-
mov
ed
as
indicated by the
marks
previously
made, placing
the
two small holes in val
ve
to-
ward the idl
e discharge
holes in throttle
body.
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