Float Style Carburetors/Adjustment (Adjustable Jet); Ball Type Non Return Valve - Tecumseh SPECTRA 37 Service And Repair Manual

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e) BALL TYPE NON RETURN VALVE (FIG 12)
The brass valve, pressed into the carburettor body has been
discontinued. The current non return valve consists of a
steel ball which seats in a taper situated in the fuel inlet
elbow.
This valve is not inter-changeable with the earlier brass
type.
To change or clean the ball and seat, proceed as follows:
a. Remove the fuel inlet elbow (noting position of nozzle).
CAUTION : do not lose the steel ball.
b. Check and clean the seat within the elbow, strip and
inspect remainder of carburettor as normal.
c. Rebuild carburettor, reposition ball in inlet elbow and
push into carb body. When the elbow is inserted
approximately 2/3 distance, apply a Loctite or similar
adhesive to obtain a good seal, and press elbow fully
into place.
NOTE - Ensure elbow is positioned in the same manner
as originally set.
Fig 12, A - Steel ball, B - Inlet elbow
3. FLOAT STYLE CARBURETTORS
These carburettors may be found in the following variants:
- Adjustable main jet
- Fixed jet choke start
- Fixed jet primer start
The carburettors may be found with fixed (Fig 13) or
adjustable (Fig 14) jet.
Fixed jets do not only differ by their size (.68 or .82 etc),
but also by the number of emulsion holes and by their
length. The correct jet depends on engine type, carburettor
and air cleaner type. Use your spare part catalogue to
identify the correct jet for a given engine type and air
cleaner execution, or consult the tables at the end of this
chapter.
a) ADJUSTMENT (ADJUSTABLE JET) (FIG 14)
- Tighten the main adjustment screw (e) and idle
adjustment screw (d) finger tight (adjustable jet type
only).
- Turn adjustment screw (e) 1.1/2 anticlockwise and idle
adjustment screw (d) one turn anticlockwise. Slacken
idle speed regulating screw (b) so that it is just out of
contact with the throttle lever (a) (throttle completely
closed) then screw in one turn to hold throttle slightly
open.
- Run engine at idle speed and adjust idle screw (d)
until smooth running is obtained.
- Adjust position of idle speed regulating screw (b) so
that engine idles to about 1,800 rpm. Use a tachometer
to check speed.
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Fig. 12
Fig. 13
Fig. 14