Chevrolet 70 1969 Series, Shop Manual

Page: 339 / 913

ENGINE FUEL SYSTEM 6M -12
dimension. Hold the tab on the float firmly against
needle valve when using the gauge. Setting is
correct when the edge of the gauge touches top of
the rib on the float. Use tool (J-4395) to bend float
lever next to float to change the float setting. Use
bending tool as illustrated in Figure 13.
After checking the float level, install air horn
and a new gasket. Locate screws, choke control
bracket and identification tag in original positions.
Connect fast idle link, accelerating pump rod, and
choke wire. Install air cleaner.
A C C E L E R A T O R P U M P T R A V E L A D J U S T M E N T
W W C Series Carburetors
Measure the total distance from the point at
top of pump lever travel when throttle lever is
moved from closed to wide open position as shown
in Figure 14. The pump travel is as indicated in
"Specifications." When necessary to adjust the
lever travel, bend the pump rod at the upper end.
EXHAUST EMISSION CONTROL SYSTEMS
GENERAL INFORMATION
Since products of combustion in gasoline en­
gines contain contaminants which cause atmos­
pheric pollution, a means to reduce narmful emis­
sions must be employed. Components used for this
purpose fall into one of the following catagories:
1. Crankcase Ventilation System (Closed Posi­
tive) .
2. Controlled Combustion System (C.C.S.).
The first system serves to prevent air pollu­
tion by re-cycling fumes from the crankcase (used
Figure
?
S —Vacuum Idle Stop (Bendix-Stromberg
Carburetor (W WC Series)1
on all engines).The other system is used for con­
trol of air pollution from exhaust system emissions
on engines sold in California.
IM P O R T A N T : All V6 gasoline engines, covered
by this supplement, sold in the State of California
are equipped with Controlled Combustion System
(C.C.S.).
POSITIVE CRANKCASE VENTILATION
SYSTEMS
For detailed information on Crankcase Venti­
lation Systems, refer to G A S O L IN E ENGINES
(SEC. 6A) of this supplement.
CONTROLLED COM BUSTION
SYSTEM (C.C.S.)
N O T E : The C .C .S. System is found only on
V6 engines sold in the State of California.
The C .C .S. System is that system which in­
creases combustion efficiency, and reduces the
hydrocarbon and carbon monoxide emissions. The
complete effectiveness of this system, as well as
full power and performance, is dependent upon the
correct idle speed, ignition timing, and idle fuel
mixtures.
The C .C .S. System imposes no additional com­
ponents, other than a specially calibrated carbur­
etor and a vacuum idle stop.
C A R B U R E T O R
The carburetor used on C .C .S. equipped ve­
hicles functions and operates the same as all other
Bendix-Stromberg carburetors used on V6 engines.
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK SH O P M A N U A L