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6C-8
1977 PONTIAC SERVICE MANUAL
MODEL 52'1 0-C CARBURETOR
CONTENTS
General Description
.............................................
6C-8
On-Car Service
....................................................
6C-10
Adjustments
..........................................................
6C-1 1
Carburetor Replacement
......................................
6C-12
GENERAL DESCRIPTION
The Model 5210-C carburetor (Figs. 6C-7 and 8) is a
staged two-barrel design with the primary bore smaller in size
than the secondary bore. The secondary throttle is
mechanically operated through inter-connecting throttle
linkage.
Fuel Filter Replacement
......................................
6C- 16
Idle Solenoid Replacement
..................................
6C- 16
Carburetor Overhaul
............................................
6C-16
SOLENOID ASSISTED
BOWL
VENT
Y
ACCELERATOR
I
TOCANISTER
PUMP
2 9 4 2
I
Fig. 6C-8 Model 52 10-C Carburetor
.-
I
Fig. 6C-7 Model 52 10-C Carburetor
The fuel inlet filter has an integral check valve to meet
Federal safety regulations for fuel loss, during vehicle roll-
over. The filter is not interchangeable with non-check filters.
The Model 5210-C carburetor utilizes four basic fuel
metering systems. They are the idle system, the primary and
secondary main metering system, the accelerating system,
and the power enrichment system.
The primary idle system (Fig. 6C-10) is a separate and
adjustable system capable of providing a proper air/fuel
mixture for both idle and low speed operation.
The main metering system (Fig. 6C-11) provides the
correct air/fuel mixture for all normal cruising speeds.
Extra fuel for smooth acceleration is supplied by a
mechanically operated accelerating system (Fig. 6C-12) to the
primary stage of the carburetor.
The power enrichment system (Figs. 6C-13 and 14)
consists of: 1) a vacuum operated fuel-enrichment valve, 2)
accelerator pump discharge nozzle pullover and 3) a
secondary stage airflow regulated pullover system. These
systems are used in conjunction with the main metering
systems to provide satisfactory performance during periods
of moderate to heavy accelerations.
Located in the primary bore are one or two vacuum ports
for distributor vacuum spark advance, EGR vacuum, and
vapor canister purge depending on emission control system.
SECONDARY
CHOKE
VALVE
PRIMARY CHOKE VALVE
I
I/
,
Fuel
Filter
Fig. 6C-9 Fuel Inlet and Float System
Refer to Section 6E, Emission Controls, for specific usage.
For improved hot engine starts a vacuum operated bowl
vent is used (Fig. 6C-15) to vent the fuel vapors to the canister
and not into the engine when the engine is not running. The
bowl vent on the L4-151 is solenoid assisted. This feature is
used in conjunction with existing internal venting through the
air horn.
A coolant heated, for L4-140, or electrically heated, for
L4-151, automatic choke system is used to provide correct
air/fuel mixtures for cold start and warm-up operation. The
L4- 140 is equipped with a vacuum break (Fig. 6C- 16) and
a secondary vacuum break on California and high altitude
vehicles to prevent prolonged fast idle. The L4-151 is
equipped with a vacuum break controlled by an external
vacuum supply and vacuum delay valve.
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