9
INLET NEEDLE AND SEAT (FLOAT CARBURETORS).
Tecumseh carburetors are built with removable seats
made out of a material called VITON
®
. These seats
are easily removed by bending the end of a paper
clip or wire with a 3/32" hook or use a #4 crochet
hook. Push the hook through the hole in the center
of the seat and remove it. Never reuse the old seat,
always replace it with a new seat.
To install a new seat, make sure the seat cavity is
clean, then moisten the seat with a drop of oil to help
it slide into place. Position the seat with the grooved
side of the seal down and carefully push the seat
into its cavity with a 5/32" flat punch until it bottoms
out.
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. Place a drop of an oil based product
such as WD-40 on the tip of the needle valve. Using
a commercially available 0-30 psi pump and gauge,
attach the pumps hose to the carburetor inlet. Apply
approximately 6 psi or until the needle pops off the
seat. The needle should seat at 1.5 psi or greater for
a minimum of 5 minutes. If the minimum 1.5 psi cannot
be maintained for this period of time, then service to
the needle and seat is required.
HOOK END
3/32"
DRIVE IN UNTIL
SEAT RESTS ON
BODY SHOULDER
INSERT THIS
FACE FIRST
INLET NEEDLE
SEATS AT THIS
POINT
5/32" FLAT PUNCH
SEAT
FLOAT HEIGHT SETTINGS
Previously the float height was set by using a 670253A
float setting tool. The new float setting will require an
11/64" drill bit. The procedure for setting the float height
is as follows. Remove the bowl gasket, then hold the
carburetor in the inverted position. Place the drill bit
across the carburetor body opposite and parallel to
the float hinge pin. Adjust the float height by bending
the tab on the float until it touches the bit.
If the required adjustment is minor, the tab adjustment
may be made without removing float and carefully inserting
a small bladed screwdriver to bend the tab. Be careful
not to damage other parts.
RIM
11/64" DRILL BIT
The inlet needle hooks onto the float tab by means of
a spring clip. To prevent binding, the long, straight,
open end of the clip must face the choke end of the
carburetor as shown.
IDLE RESTRICTOR
CAP
THROTTLE END
CHOKE END
LONG END
OF CLIP
CLIP
The idle on the Series 8 is metered using a threaded
restrictor (See illustration). Proper torque of this restrictor
is critical, it should be torqued to 5-8 in. lbs. or .5 to
1 nm, or it may vibrate loose. When the restrictor is
placed in the idle circuit passage it is capped with a
tamper resistant plastic cap. If the jet is removed for
cleaning it must be recapped to prevent tampering
when it is re-installed.
Summary of Contents for AH520 -
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