Specifications

18
Emissionized TC/Tilloston Carburetor
The Tillotson carburetor is an emissions grade carb. It
has a married idle and high speed circuitry with limited
jet adjustments on the idle (diag. 6).
Emissions Carburetor Idle Mixture
Adjustment Procedures
The carburetor is preset at the factory at a normal
setting required for initial engine operation.
Allow the engine to reach normal operating temperature
(after 3-5 minutes).
Set the engine speed control in the idle position.
NOTE
With the engine at idle speed, it must be less than 2400
R.P.M. for accurate adjustment.
Using a small tip screw driver that fits through the
access hole in the limiter cap, adjust the mixture screw
slowly clockwise until the engine R.P.M. just starts to
decrease. Stop and note this screw position. Turn the
idle mixture screw slowly counterclockwise. As the
engine increases R.P.M. continue to slowly turn the
screw counterclockwise until the engine R.P.M. starts to
decrease. Note this position and turn the mixture screw
back clockwise halfway between the two engine R.P.M.
drop off positions.
Verify the engine will accelerate from low speed to high
speed and that the idle speed remains at the desired
setting.
Once adjustments are complete, center the adjustment
limiter cap between the two stops and press inward to
engage the limiter. The limiter will snap into position
and engage the adjusting screw. All future adjustments
should now be made using the adjusting slot in the
limiter cap.
NOTE
Once the limiter cap is snapped into place it is not
possible to remove the limiter or to adjust the mixture
screw beyond the limits of the limiter assembly. Make
sure that initial adjustments are made per the above
procedure prior to engaging the limiter cap.
TC/TM, Emissionized Tecumseh
Carburetor
The Tecumseh emissions diaphragm carburetor has
fixed main and idle jets (diag. 7). It uses a married idle
and high speed circuitry. The idle has a metering jet that
can be removed for cleaning. It is covered by a small cap
that must be removed to expose the jet for servicing. No
adjustments or presets are required. The idle jet should
be turned until tight 5-8 inch pounds (0.5 Nm), and the
cap should then be installed to cover the jet.
6
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