OPEL GT-R 1973 Service Manual

6E- 501973 OPEL SERVICE MANUALMAINTENANCE AND ADJUSTMENTS
IDLE SPEED ADJUSTMENT
Note:
Idle speeds of 600 to 800 R.P.M. are normal
for engines with less than
3,ooO miles.Prior to making any adjustment to the carburetor,
the following items must be checked for proper oper-
ation and/or setting:
1. Valve Adjustment (Hydraulic lifters can be im-
properly adjusted.)
2. Dwell Angle.
3. Ignition Timing.
4. Spark Plug Gap.
5. Exhaust Gas Recirculation Valve (See “Check-
ing” under EXHAUST GAS RECIRCULATION
SYSTEM.)
After it has been ascertained that the above items are
properly adjusted and operating correctly and idle
R.P.M. is still not within specifications, proceed as
follows:
1. With air cleaner installed, run engine until normal
operating temperature is reached.
2. Remove plastic caps from the idle mixture screw
and air speed screw. See Figure
6E-11.Figure
6E-1 1 Carburetor Adjusting Screws
3. To raise R.P.M., turn air speed screw counter-
clockwise. To lower R.P.M., turn air speed screw
clockwise, thereby reducing the amount of air going
through the system.4.
Ad,just idle mixture screw until highest R.P.M. is
obtained. Alternately adjust idle mixture screw and
air speed screw until R.P.M. is obtained that is 50
R.P.M. higher than the desired final setting. This is
to be accomplished with the idle mixture screw at
best idle.
5. Turn idle mixture screw clockwise (lean) until a
decrease of 50 R.P.M. is obtained. The idle R.P.M.
will
n.ow be within specifications and proper emis-
sion control maintained.
6. Install red plastic caps over the air speed screw
and idle mixture screw.
Basic Idle AdjustmentA basic idle adjustment is to be made only if engine
idle R.P.M. correction does not result in correct idle
R.P.M. setting and engine has more than
3,OOO miles
of operation. If necessary, proceed as follows:
1. Remove plastic cap from the throttle valve stop
screw. See Figure
6E-11.2. Place the Manometer (J-23951) in a vertical posi-
tion. Turn the 2 vents on top open to equalize pres-
sure and balance gauge to read zero. With engine
idling, unplug the vacuum advance hose from the
carburetor and connect the manometer hose in its
place. See Figure 6E- 12.
Figure 6E-12 Throttle Plate Calibrator J-23951
Installed3. If the manometer does not read 1 to 8 inches of

CARBURETOR AND THROTTLE LINKAGE6E- 51
water, adjust the throttle stop screw to read 6 inches
of water (3 inches down and 3 inches up).
4. Disconnect manometer and reconnect the vacuum
advance hose.
5. Adjust idle air speed screw and mixture screw to
obtain maximum idle at 850 to 900 R.P.M. (auto-
matic transmission) or 900 to 950 R.P.M. (manual
transmission).
6. Make final adjustment by turning idle mixture
screw in to reduce idle speed 50 R.P.M.
7. Install red plastic caps over the air speed screw
and idle mixture screw. Replace plastic cap over the
throttle valve stop screw and secure in place with
Loctite.
Fast Idle Speed Adjustment
1. Remove air cleaner cover.
2. With engine off, open the throttle halfway and
close the choke valve, release the throttle, then re-
lease the choke.
3. Start engine without moving the throttle. Adjust
to 3200 to 3300 R.P.M. using 2 nuts on fast idle rod.
See Figures 6E-13 and
6E-14.Figure
6E-13 Decreasing Fast Idle Speed
CARBURETOR LINKAGE ADJUSTMENT
GT Series1. Remove air cleaner.
2. Have helper depress accelerator pedal to floor and
check to see if wide open throttle is reached at carbu-
retor.
3. If adjustment is necessary, proceed as follows:
6E-14Figure
6E-14 Increasing Fast Idle Speed
(a) Unhook accelerator pedal return spring.
(b) Remove lock spring at upper end of vertical con-
trol rod and detach rod.
(c) Lengthen or shorten control rod so that wide
open throttle is obtained at the carburetor when ac-
celerator pedal is
l/4” - l/2” from floor mat.
(d) Reinstall rod, lock spring and pedal return
spring.
Opel 19W and Manta SeriesThe carburetor bowden control wire is properly ad-
justed if, with correctly-adjusted engine idle speed,
engine at operating temperature and accelerator
pedal at an angle of 25 degrees to the vertical plane,
the ball (A) of the carburetor bowden control wire
rests against the accelerator pedal lever. See Figure
6E-15.
1. Position accelerator pedal at an angle of 25 degrees
to the vertical plane. To do this, loosen lock nut of
adjusting bolt (c) and unscrew adjusting bolt a few
turns.
Squeeze a 1 3/S” wood block (D) between accelera-
tor pedal and dash panel. See Figure
6E-15.Screw in adjusting bolt until the accelerator pedal
lever releases the wood block (D). Tighten lock nut.
2. Adjust bowden control wire at adjuster. See Figure
6E-16. Prior to doing this, adjust engine idle speed
with engine at operating temperature.
Set carburetor bowden control wire adjuster at the
bracket so that the ball (A) of the control wire rests
against part (B) of the accelerator pedal lever and the
wire core between bracket and segmental disc is not
sagging.

6E. 521973 OPEL SERVICE MANUAL
Figure 6E-15 Adjusting Accelerator Cable
Depress accelerator pedal until pedal lever touches
floor mat. The carburetor throttle valve must now be
completely opened.MAJOR REPAIR
REMOVE AND INSTALL CARBURETOR1. Remove air cleaner.
2. Remove fuel and vacuum hoses from carburetor
fittings.
3. Remove choke wire.Figure 6E-16
Bowden Control Wire Adjuster and
Segmental Disc
4. Disconnect throttle linkage by removing lock pin
and unsnapping ball socket from ball on end of throt-
tle shaft.
5. Remove carburetor by removing four nuts and
lockwashers.
Install in reverse order, noting the following:
1. Prior to carburetor insta!lation, place a new gasket
on intake manifold.
2. Make certain that all nuts and screws on the car-
buretor are securely tightened.
3. Make sure that choke housing is set on index and
that choke valve is nearly closed at room tempera-
ture. See Figure
6E-17. Make sure choke valve is free
in all positions.
Figure
LiE-17 Choke Housing Set on Index

CARBURETOR AND THROTTLE LINKAGE6E- 63
4. Adjust engine idle speed and mixture
CAUTION: : Make sure choke valve opensfully before starting idle adjustment.
THROTTLE LINKAGE REMOVAL
Removal
Opel 1900 and Manta Series1. Remove control wire from bracket and unhook it
from segmental disc. See Figure
6E-16.2. In passenger compartment, unhook wire with ball
and plastic bushing from accelerator pedal lever. See
arrow in Figure 6E- 18.
Figure 6E.18 Unhook Wire in Passenger
Compartment3. In engine compartment, pull bowden control wire
out of bracket on dash panel.
If bowden control wire is kinked or damaged in any
way, it must be replaced.
1. Feed ball and plastic bushing from engine com-
partment through opening in dash panel and hook in
accelerator pedal lever. See Figure
6E-19.2. Lightly pull wire core so that the plastic bushing
slips into bore of accelerator pedal lever.
3. Hook bowden control wire in segmental disc and
attach control wire to bracket.Figure
6E-19 Installing Ball and Plastic Bushing
4. Adjust control wire.
OVERHAUL CARBURETORDisassembly
1. Remove outer nut from end of throttle lever to
choke link. See Figure
6E-20.
Figure 6E-20 Removing Choke Link
2. Pry off vacuum case connecting lever. See Figure
6E-2 1.3. Unscrew carburetor cover.
4. Screw float needle valve out of carburetor cover
and take off copper seal ring.

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