22
High and Low Speed Adjusting Screw, Main Nozzle
When reassembling, position the coil spring on the adjusting
screws, followed by the small brass washer and the “O”
ring seal. Turn the high speed adjustment screw in
approximately one turn into the bowl retainer nut to make
an assembly (diag. 51).
On 2-7 hp. engines that use carburetors which have the
metering rod in the idle circuit (carburetor should rattle when
shaking), make certain that the idle adjustment screw is
installed when the carburetor is in an upright position or
the needle will damage the metering rod, adjustment screw
and carburetor casting.
Some carburetors are of the fixed main type and would not
have a high speed adjusting screw.
Inlet Needle and Seat
On float type carburetors, make sure the seat cavity is
clean. Moisten the seat with oil and insert the seat with
the grooved side down and away from the inlet needle.
Press the seat into the cavity using the Tecumseh
carburetor tool #670377 making sure it is firmly seated
(diag. 52).
The inlet needle hooks onto the float tab by means of a
spring clip. To prevent binding, the long, straight end of the
clip should face the air intake end of the carburetor as
shown (diag. 53).
On diaphragm carburetors the inlet needle and seat
assembly are installed by using a socket to tighten the
assembly until seated.
Needle and Seat Pop-Off Test
To test the pop-off pressure, remove the carburetor from
the engine. Be sure to drain any fuel into an approved
container. Invert the carburetor and remove the float bowl.
This test is best performed when the carburetor is placed
upside down and level in a soft jawed vice. Lift the float
and needle assembly off of the seat in order to place a
drop of WD-40 on the tip of the needle or on the seat surface.
Reposition the float and needle assembly. Using the
Tecumseh Leak Tester part # 670340, connect the high
pressure regulator to the low pressure regulator and attach
the clear low pressure air line to the carburetor fuel inlet.
Apply approximately 5-6 psi of compressed air, close the
gate valve and disconnect the low pressure guage from the
high pressure guage. Monitor the low pressure guage to
make sure the needle shouldn't drop below 1.5 psi before
1 minute of time elapses. If the minimum of 1.5 psi cannot
be maintained for this period of time, then replacement of
the needle and seat is required.
HIGH SPEED
ADJUSTMENT SCREW
SPRING
RETAINER NUT
BRASS WASHER
"O" RING
51
PRESS IN UNTIL
SEAT RESTS ON
BODY SHOULDER
52
INSERT THIS
FACE FIRST
53
THROTTLE
END
OPEN END
OF CLIP
CLIP
LONG END
OF CLIP
CHOKE
END
CARB TOOL #670377
SEAT
INLET NEEDLE MAKES
CONTACT HERE
HINGE PIN
54
FLOAT SPRING
FLOAT
INLET NEEDLE
Float Installation
Reinstall the inlet needle and float into the carburetor. The long end of the spring or clip on the inlet needle must point
toward the air intake end of the carburetor. If a float dampening spring is used, reassemble using the following steps (diag.
54).
1. Place the float upside down.
2. Position the spring on the float with the long end around and to the back side of the float’s center back tang. The ends
must point toward the choke end of the carburetor. Hook the inlet needle clip on the inside float tang so the clip end
points to the choke end of the carburetor (diag. 54).
3. Place the float, float spring, clip and inlet needle in position between the hinge legs of the carburetor. As the float
assembly nears the hinge legs, wind the outside end of the spring so it goes to the outside of the leg (counterclockwise
looking from the choke end).
TORQUE NUT TO
50 IN. LBS. (5.65 Nm)
