1973 OPEL GT-R Service Manual

6E- 541973 OPEL SERVICE MANUAL
Figure 6E-21 Removing Vacuum Case Lever
5. Unscrew vacuum diaphragm cover from choke
housing. See Figure
6E-22.Figure 6E-22 Removing Vacuum Diaphragm Cover
6. Unscrew retaining ring from automatic choke
body and take off cover.
7. Unscrew vacuum diaphragm case from carbu-
retor cover. Remove reduction jet. See Figure 6B23.
8. Take float together with spindle and leaf spring
from float chamber.
9. Pull accelerator pump discharge nozzle assemblyFigure 6E-23 Removing Vacuum Case Reduction Jet
out of carburetor housing. Nozzle is press fitted. See
Figure 6E-24.
GATOR PUMPISCHARGE NOZZLE
Figure 6E.24 Removing Accelerator Pump Discharge
10. Remove primary idle jets and secondary idle
plug. Remove primary and secondary high-speed air
jets.
11. Remove primary and secondary main metering
jets.
12. Remove cotter pin from pump connecting rod.
Remove accelerator pump.
13. Remove idle mixture adjusting screw from throt-
tle valve body. Remove idle air adjusting screw from

CARBURETOR AND THROTTLE LINKAGE6E- 55
float chamber. Clean all parts and blow out with
compressed air. Replace gaskets and seal rings.
14. Check actuating parts in automatic choke body,
including diaphragm, for wear. Check pull rod for
free operation. See Figure 6E-25.15. Remove choke assembly by removing choke
valve and 2 choke housing
- to - carburetor screws.
Figure 6E-25 Checking Automatic Choke Parts
16. Check vacuum case assembly. If bushing is worn,
replace vacuum case assembly. See Figure 6B27.
Figure
6E-27 Checking Vacuum Case Brass Bushings
17. Install secondary vacuum diaphragm case assem-
bly. See Figure 6B28.
18. Install gasket and shield between automatic
choke cover and automatic choke body.Figure
6E-28 Installing Vacuum Case Assembly
19. Install automatic choke cover so that the catch
of the
b&metal spring is positioned onto bent end of
the intermediate lever. See Figure 6B29.
Figure 6G29 Installing Automatic Choke Cover
20. Align and tighten automatic choke cover. Choke
valve should be nearly closed at room temperature.
21. Check vent valve for free operation. Valve rod
must not be bent.
22. Screw in jets according to calibration table.
Never interchange parts of the primary and
second-
xy barrel. See Figure 6E-37.23. Install the throttle body to the bowl, using new
throttle body gasket. Adjust secondary throttle valve
gap by loosening lock nut on the secondary throttle

6E- 561973 OPEL SERVICE MANUAL
valve stop screw. Loosen the stop screw until the
valve is completely closed. Turn the screw in l/4turn from closed position, hold, and tighten lock nut.
This is done to insure that the throttle blade will not
stick closed. See Figure
6E-30.PUMPFigure 6E-30 Adjusting Secondary Throttle Valve Gap
24. Install accelerator pump connecting rod in lower
hole of primary throttle shaft lever and cotter pin in
outboard hole at accelerator pump actuating lever
end. Paying attention to proper arrangement of cot-
ter pin and washers. See Figure
6E-2.25. With throttle plate completely closed, there
should be no clearance between the pump levei and
the pump plunger rod.
26. If a clearance is present, loosen 4 accelerator
Figure
6E-31 Accelerator Pump CoverFigure 6C32 Accelerator Pump Cover
pump cover retaining screws and allow the
dia-’phragm spring to push plunger against lever so that
a zero clearance exists. Then retighten the screws.
See Figures
6E-3 1 and 6E-32.27. Insert accelerator pump discharge nozzle so that
the bent tube end points into suction channel of the
primary barrel.
28. Fill the bowl with fuel.
29. With fuel in bowl, slowly open the throttle and
observe the accelerator pump pressure relief valve
exhaust ports and where it seats into the bowl. See
Figure
6E-33. Fuel should not be bleeding back into
the bowl from the exhaust ports or where the relief
valve seats, but a steady stream of fuel should dis-
charge from the discharge nozzle.
30. With fuel in bowl, rapidly open the throttle atid
observe the exhaust ports of the pressure relief valve.
See Figure
6E-33. Fuel should~exhaust’from the ac-
celerator pump pressure relief valve exhaust ports.
3 1. If the pressure relief valve malfunctions, remove
it and replace with a new one.
32. No float adjustment is possible, so check position
of float arm by comparing with a new float of thesame carburetor type. If float arm is bent, replace
float.

CARBURETOR AND THROTTLE LINKAGE6E- 57
ACCELERATOR PUMP
PRESSURE RELIEF
VALVE SEAT
ALVE
VENT DISCHARGE
(AIR BUBBLES FROM THIS
HOLE
IS NORMAL)
PUMP INLET
VALVE EXHAUST
PORT
--6E-33
Figure 6E-33 Carburetor Fuel Bowl
33. Install float and pivot rod making sure rod is
seated in casting.36. Install new air horn gasket so that the holes in
the gasket coincide with the screw holes in carbu-
retor housing. See Figure
6E-35.34. Install leaf spring so that spring ends rest on float
spindle. See Figure
6E-34.37. On vent valve, pay attention to cotter pin position
and arrangement of washers.
3.5. Screw in float needle valve together with copper38. Basic adjustment of idle mixture adjusting screw
seal ring
(.08 in. thick).is 5 turns open.

6E- 581973 OPEL SERVICE MANUAL
Figure 6E-34 Leaf Spring Installed
1 6E-36
Figure 6E-36 Checking Vent Valve Adjustment
39. Check compression of vent valve lower spring. It
should be compressed
l/4 inch with throttle valve
completely closed. See Figure
6E-36.40. Correct by bending valve lever.
Figure
6E-35 Installing Cover Gasket
SPECIFICATIONS
GENERAL SPECIFICATIONSCompression Ratio
........................................................................................................7.6 to 1
Fuel Required
................................(...........................................................................Low Lead
Fuel Tank Capacity (Gallons)
Opel1900andManta..
....................................................................................................11.9
GT...................................................................................................................................13.2Fuel Gauge Type
........................................................................................................Electrical
FuelPumpType
......................................................................................................Mechanical
FuelPumpDrive
..................................................................................EccentriconCamshaft
Fuel Pump Pressure at 1950 RPM
......................................................................3.1 to 3.7 psi
FuelFilter
............................................................................................................In-LineFilter
CarburetorMakeandType................................................I-Solex2BBLAutomaticChoke
AirCleanerElementType
..........................................................................FiberMesh-Paper

CARBURETOR AND THROTTLE LINKAGE6E- 59
Figure 6E-37 Carburetor Specifications

6F- 601973 OPEL SERVICE MANUAL
EMISSION CONTROL SYSTEMS
ALL MODELS
CONTENTS
Subject
DESCRIPTION AND OPERATION:
DescriptionandOperationofO.E.C.S.. . . . . . . . . . . . . . . . . . . . . . . .Exhaust
GasRecirculationSystem. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DIAGNOSIS:
Testing Therm0 Air Cleaner Operation
. . . . . . . . . . . . . . . . . . . . . .Exhaust
GasRecirculationSystem. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .MAINTENANCE AND ADJUSTMENTS:
Exhaust GAS Recirculation System
. . . . . . . . . . . . . . . . . . . . . . . . . . . .MAJOR REPAIR:
Removal and Replacement of O.E.C.S. Units
. . . . . . . . . .SPECIFICATIONS:
Opel Emission Control System Specifications
. . . . . . . .Page No.
6F-60
6F-62
6F-62
6F-636F-636F-636F-64
DESCRIPTION AND OPERATION
OPEL EMISSION CONTROL SYSTEM (O.E.C.S.)All 1973 cars must be capable of passing certain tests
which measure the quantity of unburned impurities
in the exhaust system. Federal law places a limit on
the hydrocarbon and carbon monoxide emissions
from the exhaust system. The purpose of this law is
to keep the atmosphere cleaner, particularly in popu-
lous areas where these impurities add to the smog
problem. Basically, excessive exhaust emissions are
caused by incomplete combustion of the air-fuel mix-
ture in the cylinders.
The basic components of the OECS on the 1.9 liter
engines are (1) leaned out carburetion, (2) heated air
(except GT), and (3) tuned spark timing.
(1) The carburetor idle system is leaned out and
special features are incorporated into the carburetors
to make possible additional idle mixture adjustments
over and above those manufactured into the carbu-
retors.
(2) The heated air package consists of a heat stove,
a corrugated paper heated air pipe, and an air cleanercontaining a temperature controlled door operated
by vacuum through a temperature sensor. See Figure6F-1.The heat stove is a sheet metal cover, shaped to and
bolted onto the exhaust manifold. Air drawn in along
Figure
6F-1 Heated Air System Installed

EMISSION CONTROL SYSTEMS6F- 61I
1.HEAT STOVE
2.CONNECTING HOSE.
3.VACUUM DIAPHRAGM
4.VALVE (El-METAL SPRING)
5.VACUUM HOSES
6.AIR CLEANER HOUSING
7.CARBURETOR
BF-2
Figure 6F-2 Heated Air Systemthe lower edge of the stove passes across the manifold
surface, picking up heat. The heated air is drawn out
from the upper end of the manifold, through the
heated air pipe into the snorkel of the air cleaner. See
Figure
6F-2.The temperature control air cleaner is designed to
mix this heated air with cold air from under the hood
so that carburetor inlet air temperature averages
about 115 degrees. This mixing is done by an air door
located in the air cleaner snorkel. Most of the time,
the door will be partially open, as required, to control
the temperature. When the underhood temperature
reaches about 135 degrees, the door will close tight,
not allowing any more warm air from the mainifold
to enter the snorkel of the air cleaner. Obviously, if
underhood temperatures rise above 135 degrees, theair cleaner will no longer be able to control tempera-ture and the inlet air temperature will rise with
un-derhood temperature.
The temperature door is moved by a diaphragm type
vacuum motor. When there is no vacuum present in
the motor, the diaphragm spring forces the door
closed. Whenever the engine is running, the amount
of vacuum present in the vacuum motor depends on
the temperature sensor in the air cleaner which is
located in the vacuum line between the intake mani-
fold and the vacuum motor. In the sensor, a bi-metal
temperature sensing spring starts to open a valve to
bleed more air into the vacuum line whenever the
temperature in the air cleaner rises above about 115
degrees. Whenever the temperature falls below about
115 degrees, the sensing spring starts to close the air