1973 OPEL GT-R light

6A. 201973 OPEL SERVICE MANUAL
diameter at the right angle to the piston pin is greater
than the diameter parallel to the piston pin. When a
piston is checked for size, it must be measured with
micrometers applied to the skirt at ,points 90 degrees
to the piston pin. See Figure
6A-32. The piston
should be measured (for fitting p&poses) 2
l/2 in-
ches below the top of piston.
MEASURE AT
Figure 6A-32
Measuring,PistonInspect bearing surfaces of piston pins. Check for
wear by measuring worn and unworn surfaces with
micrometers. Rough or worn pins should be re-
placed. Check fit of piston pins in piston bosses.
Occasionally pins will be found tight due to gum or
varnish deposits. This may be corrected by removing
the deposit with a suitable solveni. If piston bosses
are worn out-of-round or oversize, the piston and pin
assembly must be replaced. Oversize pins are not
practical because the pin is a press fit in the connect-
ing rod. Piston pins must tit the piston with
0X4”to
.OCHl7” clearance.
Examine all piston rings for scores, chips or cracks.
Check compression rings for tension by comparing
with new rings. Check gap of compression rings by
placing rings in bore at bottom of ring travel. Meas-
ure gap with feeler gage. Gap should be between
,011” and .02.1”. If gaps are excessive (over .021”) it
indicates the rings have worn considerably and
should be replaced.
No attempt should be made to cut down oversize
pistons to fit cylinder bores. This practice
will de-
stroy the surface treatment and affect the weight.
The
sma/Jest possible oversize service pistons shouId
be used and the cylinder
bores should be honed to
size for proper clearance.1. Before installing piston, piston rings, or reboring
cylinders, observe the following:Cylinder bores may not be the same size. Standard
replacement piston sizes are in the midpoint of the
cylinder bore size range. Therefore, it may be neces-
sary to hone cylinders for correct piston tit. Out-of-
round on cylinder bore must not exceed
.ooO5”maximum with a taper of not over
.OilO5”.Before the honing or reboring operation is started,
measure all new pistons with micrometer contacting
at points exactly 90 degrees to piston pin (Figure6A-32) then select the smallest piston for the first
fitting. The slight variation usually found between
pistons in a set may provide for correction if the first
piston has excessive clearance.
If wear of cylinder does not exceed
.005” honing is
recommended for truing the bore. If wear or
out-of-round exceeds these limits, the bore should be trued
up with a fly cutter boring bar and then finish honed.
When reboring cylinders, all crankshaft bearing caps
must be in place and tightened to proper torque to
avoid distortion ofbores in final assembly. Always be
certain the crankshaft is out of the way of the boring
cutter when boring each cylinder. When making thefinal cut with boring bar, leave
,001 w on the diameter
for finish honing to give the required clearance speci-
fied.When honing cylinders, use clean sharp stones of
proper grade for the required amount of metal to be
removed, in accordance with instructions of the hone
manufacturer. Dull or dirty stones cut unevenly and
generate excessive heat. When using coarse or
medium grade stones use care to leave sufficient
metal so that all stone marks may be removed with
the fine stones used for finishing in order to maintain
proper clearance.
When finish honing, pass the hone through the entire
length of cylinder at the rate of approximately 60
cycles per minute. This should produce the desired
45 degree cross hatch pattern on cylinder walls
which will insure maximum ring life and minimum
oil consumption.
It is of the greatest importance that refinished cylin-
der bores have not over
.0005” out-of-round or ta-
pered. Each bore must be final honed to remove all
stone or cutter marks and provide a smooth surface.
During final honing, each piston must be fitted in-
dividually to the bore in which it will be installed and
should be marked to insure correct installation.
After final honing and before the piston is checked
for fit, each cylinder bore must be thoroughly
washed to remove all traces of abrasive and then
dried. The dry bore should then be brushed clean
with a power-driven iibre brush. If all traces of abra-
sive are not removed, rapid wear of new pistons and
rings will result. Fit new pistons in the following
manner:

ENGINE MECHANICAL AND MOUNTS6A- 21
2.. Expand a telescope gage to fit the cylinder bore at
right angles to the piston pin 2-l/2” from top. See
Figure 6A-33.cylinders, the glazed cylinder walls should be slightly
dulled without increasing the bore diameter by
means of the finest grade honing stones.
TELESCOPE GAUGE1
Figure 6A-33 Checking Cylinder Bores
TELESCOPE/GAUGE
MICROMETER
Figure
6A-34 Measuring Telescope Gage3. Measure the piston to be installed. See Figure6A-32. The piston must be measured at right angles
to the piston pin
2-l/2” below the top of piston. The
piston must be between
.C008” and .0012” smaller
than the cylinder bore.
Both block and piston must be at approximately the
same temperature when measurements are made or
expansion errors will occur. A
dif.ference of 10 de-
grees F between parts is sufficient to produce a varia-
tion of .0005”.
Fitting New Piston RingsWhen new piston rings are installed without reboringNew piston rings must be checked for clearance in
piston grooves and for gap in cylinder bores; how-
ever, the flexible oil rings are not checked for gap.
The cylinder bores and piston grooves must be clean,
dry, and free of carbon and burrs.
To check the end gap of compression rings, place the
ring in the cylinder in which it will be used and
square it in the bore by tapping with the lower end
of a piston. Measure the gap with feeler gages.
Piston ring end gap should be
,014” - ,022” (top) and
,014” - ,022” (2nd) and the oil ring end gap should
be
.015” - ,055”.
If gap is less than specified, file the ends of rings
carefully with a smooth tile to obtain proper gap.
Install piston rings as follows:
1. Upper ring is chrome plated and can be installed
either way up. Number two (2) ring has to be in-
stalled with the marking “top” up. Oil ring can be
installed either way
up. See Figure 6A-35.
1. PISTON
2. NO.
I COMPRESSION RING - INSTALLED
WITH EITHER SIDE UP.
3. NO. 2 COMPRESSION RING - INSTALLED
WITH “TOP” MARKING TOWARDS THE TOP.
4. UPPER AND LOWER STEEL BAND RING
-
INSTALLED WITH EITHER SIDE UP.5. INTERMEDIATED RING
- INSTALLED WITH
EITHER SIDE UP.
6A-35
Figure 6A.35 Arrangement of Piston Rings2. Install piston rings so gaps are positioned as shown
in Figure 6A-36.

ENGINE MECHANICAL AND MOUNTS6A- 27
With feeler gauge, check gear backlash. It should be
between
.I?04 in. and .C!OS in. See Figure 6A-46.3. Remove (2) bolts holding pipe and screen assem-
bly to cylinder block. See Figure 6A-47.
FEELERGAUGE6A-46
Figure 6A-46 Measuring Oil Pump Gear Backlash
Checking Oil Pump Relief Valve
For Proper Functioning
1. Unscrew plug and check spring and relief valve
plunger in oil pump cover for dirt particles and free
operation. If required, carefully clean plunger and
seat. Pressure relief plunger sticking as a result of
foreign material or sludge build-up in the oil pump
cover can cause loss of oil pressure.
Removal and Inspection of Oil Pump
Pipe and Screen Assembly
1. Remove oil pan.
2. Clean oil pan. Make sure the gasket surfaces and
pan and block are clean.
Figure 6A-47 Installation of Pipe and Screen
Assembly4. Clean the screen and housing thoroughly in sol-
vent and blow dry with air stream.
Installation of Oil Pump and Screen Assembly
Install by reversing removal procedures, paying par-
ticular attention to the following points.
1. Make sure oil pump pipe flange gasket surface of
block is smooth and free of dirt.
2. Use a new gasket and install assembly.
3. Tighten pan bolts evenly. Do not over-tighten.
Torque to 5 lb. ft.
SPECIFICATIONSBOLT TORQUE SPECIFICATIONS
Use a reliable torque wrench to tighten all parts listed, to insure proper
tightness without straining or distorting parts. These specifications are for
clean and lightly-lubricated threads only; dry or dirty threads produce in-
creased friction which prevents accurate measurement of tightness.

COOLING SYSTEM6B- 33
remove drain plug on right.side of cylinder block. Set
heater temperature control valve at full heat posi-
tion. After the cooling system is drained, and plugs
reinstalled, fill the system with clean water. Run the
engine long enough to open the thermostat for com-
plete circulation through the system, then com-
pletely drain the cooling system before sediment has
a chance to settle.
Conditioning the Cooling System
“Rust Inhibitor and Stop Leak”, or equivalent listed
under Group 8.800 is recommended for use in the
cooling system, particularly when preparing for in-
stallation of anti-freeze solution. This material stops
small seepage leaks, has rust preventive properties
and its soluble oil is effective in eliminating a squeal-
ing noise which sometimes develops at the water
pump seal washer. Instructions for its application are
printed on the conditioner bottle.
It is very important to make certain that the cooling
system is properly prepared before an anti-freeze so-
lution is installed, otherwise loss of solution through
leakage may occur or seepage may result in damage
to the engine. The cooling system should be drained
and flushed as described under Draining and Flush-
ing Cooling System. All joints should be checked for
leakage and corrected, and the conditioner described
above should be added with the anti-freeze solution.
Inspect the water pump, radiator core, heater and
defroster cores, water jacket plugs, and edge of cylin-
der head gaskets for evidence of water leaks. Tighten
all hose clamps in the cooling and heating systems
and replace any deteriorated hoses.
Using and Testing Anti-Freeze
Solutions
Inhibited year around (ethylene glycol type) engine
coolant solution which is formulated to withstand
two full calendar years of normal operation without
draining or adding inhibitors should be used at all
times. Freeze protection should be provided to pro-
tect against corrosion. When adding solution due to
loss of coolant for any reason or in areas where tem-
peratures lower than minus 20 degrees F. may be
encountered, a sufficient amount of any of the sev-
eral brands of year around coolant (Ethylene Glycol
base) compatible to GM Specification 1899-M avail-
able on the market should be used. Water or alcohol
base coolants are not recommended for this vehicle
at any time.
If for any reason water only is used as a coolant in
an emergency, it is extremely important that Buick
Heavy Duty Cooling System Protector and Water
Pump Lubricant or equivalent be added to the cool-
ing system as soon as possible. If any other cooling
System protector is used, be certain it is labeled toindicate that it meets General Motors Specification
GM 1894-M. It should be recognized that this is only
a temporary measure. The manufacture intends that
permanent type coolant solution be used year around
in the cooling system.
The cooling system should be completely drained
and the recommended coolant installed every two (2)years.It is advisable to test the anti-freeze solution at inter-
vals during the winter to make certain that the solu-
tion has not been weakened. Use only hydrometers
which are calibrated to read both the specific gravity
and the temperature, and have a table or other means
of converting the freezing point at various tempera-
tures of solution. Disregarding the temperature of
the solution when making the test may cause an error
as large as 30 degrees F. Care must be exercised to
use the correct float or table for the particular type
of anti-freeze being tested.
Fan Belt Adjustment or Replacement
A tight fan belt will cause rapid wear of the alterna-
tor and water pump bearings. A loose belt will slip
and wear excessively and will cause noise, engine
over-heating, and unsteady alternator output. A fan
belt which is cracked or frayed, or which is worn so
that it bottoms in the pulleys should be replaced. The
fan belt may be replaced by loosening the alternator
brace at alternator, slightly loosening the alternator
mounting bolts and moving alternator inward to pro-
vide maximum slack in the belt.
The alternator must be moved outward to adjust the
fan belt. After the generator brace and mounting
bolts are securely tightened, the fan belt tension
should be 45 lb. using Tensioner J-23600.
WARNING: Zfa
fan blade is bent or damaged in any
way, no attempt should be made to repair and reuse
the damaged part. A bent or damaged fan assembly
should always be replaced with a new
fal. assembly.
It is essential that fan assemblies remain in proper
balance and proper balance cannot be assured once
a fan assembly has been bent or damaged. A fan
assembly that is not in proper balance could fail and
fly apart during subsequent
we creating an ex-
tremely dangerous condition.
Radiator Thermostat Inspection and Test
A sticking radiator thermostat will prevent the cool-
ing system from functioning properly. If the thermo-
stat sticks in the open position, the engine will warm
up very slowly. If the thermostat sticks in the closed
position, the engine will overheat.
The thermostat may be removed for inspection and

6B- 341973 OPEL SERVICE MANUAL
test by partially draining the cooling system and dis-
connecting the water outlet housing from the ther-
mostat housing which is mounted on the right front
side of cylinder head.
The standard thermostat valve should start to open
at 189 degrees F and fully open at approximately 212
degrees F. If thermostat does not operate at specified
temperatures, it should be replaced as it cannot be
repaired.MAJOR REPAIR
WATER PUMP REPAIRSThe water pump bearing outer race is shrunk fit into
the water pump cover. For this reason the cover,
shaft bearing, and hub are not repairable.
Water Pump RemovalOpel radiators do not have a drain plug. Drain radia-
tor by first, loosening radiator cap, then remove
lower hose from lower radiator tank.
1. Drain coolant into a clean container. Remove
radiator and shroud.
2. Remove fan belt.
3. Remove fan blade and pulley on water pump shaft.
4. Disconnect inlet hose and heater hose from water
pump. Remove bolts, pump assembly and gasket
from timing chain cover.
5. Check pump shaft bearing for end play or rough-
ness in operation. If bearings are not in serviceable
condition, the assembly must be replaced.
Water Pump Installation1. Make sure the gasket surfaces on pump and timing
chain covers are clean. Install pump assembly with
new gasket. Bolts must be tightened uniformly.
Torque to 11 lb. ft.
2. Install radiator and shroud. Connect radiator hose
to pump inlet and heater hose to nipple.
3. Install fan pulley and fan blade, tighten attaching
bolts securely. Install belts and adjust for proper
tension.4. Fill cooling system and check
,for leaks at pump
and hose joints.
RADIATOR REMOVAL AND INSTALLATION
RemovalI. Loosen radiator cap, then remove lower radiator
hose and drain radiator coolant into suitable con-
tainer.
2. On vehicles with automatic transmission, unscrew
oil lines from connectors on lower radiator tank and
plug lines. On GT models with automatic transmis-
sion the lines have to be disconnected at the coupling
before removing from the tank. It is essential that no
dirt enters the oil lines. When unscrewing oil lines,
hold connectors on lower radiator tank with pliers to
avoid leakages. Ensure that no dirt enters oil cooler.
3. Remove lower attaching nut and slide radiator
upward and out of engine compartment.
Installation1. Install radiat,or into engine compartment and se-
cure lower attaching nut.
2. On vehicles with automatic transmissions, fasten
oil cooler lines to lower radiator tank. It is essential
that no dirt enters the oil lines. When tightening oil
lines, hold connectors on lower radiator tank with
pliers to avoid leakages. Ensure that no dirt enters oil
cooler. Torque to 1 I-15
lbs.ft.3. Install lower radiator hose and add collected coo-
lant.
All Opels are provided with a radiator initial fill of
an antifreeze solution containing corrosion inhibitor.
The antifreeze has either a glycol or glycerin base
and protects the engine against freezing, down to
minus 22 degrees F. (minus 30 degrees C.). Before
the start of the cold season, coolant must be checked
with a hydrometer and if necessary, brought to the
necessary specific gravity by adding anti-freeze with
a glycol or glycerin base. As the specific gravities of
all anti- freeze solutions having a glycol or glycerin
base are practically the same, the hydrometer can be
used for all these types. Because of the tolerances of
the hydrometer, or slight differences in specific
gravity, variations of plus or minus 5 degrees can be
expected. Coolant must be checked at a temperature
of plus 68 degrees F. (plus 20 degrees C.)

6C- 361973 OPEL SERVICE MANUAL
FUEL SYSTEM
ALL MODELS
CONTENTS
Subject
DESCRIPTION AND OPERATION:
Fuel Pump. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . .Evaporation Control System
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DIAGNOSIS:
(Not Applicable)
MAINTENANCE AND ADJUSTMENTS:
Cleaning Fuel Pump Strainer.,....................................
*.Evaporation Control System
. . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .MAJOR REPAIR:
Fuel Tank
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Fuel Lines and Fuel Tank Gauge Units
. . . . . . . . . . . . . . . . . . . . . .SPECIFICATIONS:
Fuel System Specifications
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page No.6C-366C-376C-376C-386C-396C-416C-41
DESCRIPTION AND OPERATION
FUEL PUMPThe 1.9 liter engine uses a push rod type fuel pump.
The push rod is actuated by an eccentric on the
distributor shaft. The push rod is held in contact
with the eccentric at all times by a push rod spring.
Each time the push rod is on the high part of the
eccentric, the lighter diaphragm spring will push the
diaphragm to replace any fuel used in the carburetor.
The diaphragm seldom operates through a full
stroke; under normal driving conditions, the dia-
phragm moves only a few tenths of an inch.
Fuel pump pressure is determined by the compres-
sion of the diaphragm spring. Low pressure or pres-
sure leak- down generally indicates a leaky
diaphragm or check valves.
Two holes in the lower part of the fuel pump serve
to ventilate the space below the diaphragm and to
drain any fuel which may have entered. If any fuel
comes from these holes, this indicates a defective
diaphragm.When replacing the fuel pump, make sure the asbe-
stos spacer is in place with a gasket on each side. See
Figure 6C- 1. Because of the location of the fuel pump
eccentric on the distributor shaft, the fuel pump
Figure
6C-1 Installing Push Rod Type Fuel Pump

SE- 441973 OPEL SERVICE MANUAL
CARBURETOR AND THROTTLE LINKAGE
ALL MODELS
CONTENTS
Subject
DESCRIPTION AND OPERATION:
Carburetor
. . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DIAGNOSIS:
Carburetor
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .MAINTENANCE AND ADJUSTMENTS:
Idle Speed and Mixture Adjustments
. . . . . . . . . . . . . . . . . . . . . . . .Fast Idle Speed Adjustment
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Throttle Linkage Adjustment
. . . . . . . . . . . . . . . , . , . . . . . . . . . . . . . . . . . . . . . .MAJOR REPAIR:
RemoveandInstallCarburetor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I...Throttle Linkage Removal
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .OverhaulCarburetor
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .SPECIFICATIONS:
Carburetor
Specifications
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page No.
6E-44
6E-49
6E-50
6E-51
6E-51
6E-52
6E-53
6E-53
6E-58
DESCRIPTION AND OPERATION
CARBURETORThe two-barrel carburetor for all 1973 Opel1
19G0,Manta and GT models is a down-draft carburetor
with two barrels of 1.25 inch diameter each. It has
an automatic choke and a secondary valve operated
by a vacuum diaphragm, except when installed in an
Opel GT. In the GT, the secondary throttle valve is
operated by mechanical linkage from the primary
throttle valve.
The two-barrel carburetor consists of three main
parts
- throttle body, float chamber and air horn.
Each barrel is a separate system, but both barrels
discharge into a common inlet in the intake mani-
fold. The secondary barrel does not have a choke
valve or an accelerator pump. See Figure
6E-2.The throttle valve of the primary barrel is opened
through the throttle linkage. When the primary
throttle valve is almost open, at approximately half
of the maximum engine RPM, the secondary throttlevalve is opened by vacuum applied through a
vacuum diaphragm case. See Figure
6E-3. The sec-
ondary throttle valve on the GT model is opened by
mechanical linkage from the primary throttle shaft.
Choke SystemThe automatic choke is operated by a bi-metal
spring. The tension of the spring
- depending on
temperature of the heater coil
- decreases with rising
temperature and the choke valve opens progressively
until it is completely opened at engine operating tem-
perature. The choke valve is off-set so that choke
valve opening increases as air flow increases.
If the choke valve is closed, the throttle valve is
opened slightly to provide a fast idle speed. This is
done through a cam, abutment lever and throttle
connecting link. With the throttle valve opened
slightly, the vacuum during cranking can take effect
up to the choke valve, thereby drawing ample fuel
out of the main nozzle. See Figure
6E-4.With rising temperature of the heater coil, the choke

CARBURETOR AND THROTTLE LINKAGE6E- 4512345678Sectional View Of 19 US Carburetor (both barrels)
1 PIug(transition channels, secondary barrel)
6 Float chamber
2Carburetor
cover7Idleairpassage
3Vent tube
8Idleairiet4Transit’
,n iet9 Idle air adjusting screw
5 Transition air iet10 Mixture adjusting screw
6E-1Figure 6E-1 Sectional View of Primary and Secondary Barrels
valve gradually opens and the mixture
become+leaner. During this process, the abutment lever
changes position on the fast idle cam, further closingBefore starting a cold engine slowly, depress the ac-celerator pedal three times before engaging the
starter.
the throttle valve until, the engine is at normal oper-
ating temperature, the choke valve is wide open and
the throttle valve is in slow idle position.
Idle and Part Throttle SystemA choke diaphragm is connected to the intermediate
lever of the choke valve spindle through a pull rod.
The vacuum, which develops below the throttle
valve, takes effect on the diaphragm through a
vacuum passage. See Figure
6E-4. As soon as the
engine starts, this vacuum pulls the choke valve
slightly open; the amount of choke valve opening
depends on the amount of vacuum, which depends
on the engine load. Therefore, with a light engine
load, the choke valve will open slightly; with a heavy
engine load, the valve will close slightly to give a
richer mixture as required for this engine load.At engine idle grid during low speed (part throttle)
operation, fuel is drawn from the emulsion tube bore,
controlled by the idle jet and mixed with air entering
through idle air bleeds (Figure 6E-1) and ports in thethrottle body. This mixture is drawn downward to
the three ports near the throttle valve. When the
throttle valve is closed, the mixture is drawn from
the lowest port and mixed with air by-passing the
throttle valve to form the idle mixture.
Turning the idle mixture screw (Figure
6E-1) inward
results in a leaner mixture, and turning it out results