Choke System - Chevrolet Light Duty Truck 1973 Service Manual

6 M - 1 6 ENGINE FUEL
NOTE: Also refer to the "Emission Control
Systems" Booklet for required maintenance
and warranty information.
Timing Points (Dwell), Idle Speed - These adjustments
must be performed accurately, following the specifica­
tions shown on the label under the hood. Adjustments
must be made with test equipment known to be accurate.
Proper functioning of the carburetor is particularly essential
to control of emissions. Correct mixtures for emission
compliance and idle quality have been preset. Plastic idle
mixture limiters have been installed on the idle mixture
screws to preclude unauthorized adjustment. These idle
limiters are not to be removed unless made necessary by
Fig. 20--Choke System
M AINTEN A NC E A N D ADJUSTMENTS
some major carburetor repair or replacement which affects
the idle screw adjustment.
CHOKE-Choke mechanism should be checked for free
operation. A binding condition may have developed
from petroleum gum formation on the choke shaft or
from damage. Choke shafts can usually be cleaned
without disassembly by using United Delco X
Carburetor and Combustion Cham ber Conditioner or
equivalent.
BOLTS, CARBURETOR TO M ANIFOLD-Carburetor
attaching bolts and/or nuts should be carefully adjusted
to correct torque to compensate for compression of
gasket at first 4 months or 6,000 miles of vehicle
operation only.
FILTER-CARBURETOR A N D /O R FUEL PUMP-A
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LIGHT DUTY TRUCK SERVICE MANUAL