1973 OPEL GT-R engine

IIIGNITION SYSTEMlC- 19
11. (Startx position.) The ignition key must be
released as soon as engine starts. The switch then
returns aujomatically to the on position.
IGNITION
GOILThe ignition coil consists of a laminated non- mag-
netic iron
(core enclosed by two coils; the primary
winding and the secondary winding.
The prim+y circuit consists of the power source
(battery), the ignition switch, the ignition coil pri-
mary winding, the distributor breaker points with
ignition condenser connected in parallel, and all con-
necting
lo& tension wiring.
The secondary circuit consists of the ignition coil
secondary ‘winding, the spark plugs, all connecting
high tens@ wiring, the distributor cap and the
ro-tor.
When the’ ignition switch is turned on and the
breaker pdints are closed, current flows through the
ignition
c&l primary winding and produces a mag-
netic field wound the coil windings.
When the breaker points are separated by the revolv-
ing distributor cam, the magnetic field collapses and
induces a high voltage surge in the secondary wind-
ing,
produ;cing a spark between the spark plug elec-
trodes. ,
The ignitidn condenser which is connected in paral-
lel with the breaker points, prevents arcing between
the
separa’ted breaker contacts, and current flow
after~ the breaker points have been separated, thus
causing a kery rapid collapse of the magnetic field
around th$ Ignition coil.
/
IGNITION ‘DISTRIBUTORThe ignitidn distributor breaks the primary current,distributeslthe high voltage surges induced in the coil
secondary winding to the spark plugs according to
the engin< tiring order and sets ignition timing in
relation to. engine RPM and load.
The housi+g of the distributor contains the centrifu-
gal advance mechanism and the movable breaker
plate with’s breaker lever and contact support. The
vacuum advance mechanism is attached to the
breaker plate and mounted on the outside of the
distributor, housing. See Figure lC-1.
The distributor shaft is driven by a helical gear on the
camshaft and in turn drives the engine oil pump. The
ignition condenser is mounted on the outside of the
housing. The engine output is to a large extent in-
fluenced b) the ignition timing. Maximum engine
performance is obtained when the combustion proc-
ess is well underway as the piston starts down on thepower stroke. The air-fuel charges are, however, not
burned instantly, so it is necessary to advance the
spark in relation to the piston top dead center as
engine speed increases or as engine load decreases.
If the spark is too far advanced, the engine knocks,
causing a drop in engine power output and overheat-
ing. If the spark is retarded, part of the energy deve-
loped during combustion is wasted which will result
in reduced engine power output, excessive fuel con-
sumption and overheating.
The ignition distributor has a double acting double
diaphragm vacuum unit. See Figure lC-1. The ad-
vance unit is supplied with “ported” vacuum. That
is, vacuum is supplied from a port in the primary
barrel of the carburetor located just above the closed
throttle valve. This port supplies no vacuum during
idling nor during closed throttle deceleration, but
supplies full intake manifold vacuum at all speeds
where the throttle valve is opened enough to uncover
the port.
Figure lC-1 Ignition Distributor
The retard unit is supplied with intake manifold
vacuum at all times by means of a line connected
directly to the intake manifold. During idling and
deceleration, when there is no vacuum to the ad-
vance unit, the retard unit will cause the timing to be
retarded 5 degrees. However, during part throttle
operation when there is vacuum to the advance unit,
the advance unit will overpower the retard unit so
that the retard unit has no effect on timing.
The purpose of the retard unit is to reduce hydrocar-
bon and carbon monoxide emissions during idling
and deceleration, where they are especially bad.
In order to avoid voltage losses for easier starting, a
plastic cover has been inserted in the distributor be-
low the rotor as a seperator to keep the inside of the
distributor cup free from condensation.

I
ilC- 201973 OPEL SERVICE MANUAL
There is also a plastic hood slipped over the distrivu-tar cap with an outlet for the ignition cables as an
added protection against moisture from the outside.
See Figure lC-2.
Figure lC-2 Ignition Distributor With Hood Installed
MAINTENANCE AND ADJUSTMENTS
CONTACT POINT REPLACEMENT
Removing Contact Points1. Remove contact support lock
,screw and remqve
contact point support. If condenser is to be replaced,
it will be necessary to replace condenser and
1eads;asan assembly.
Installing Contact Points1. Lightly lubricate distributor cam with high tein-perature cam and ball bearing lubricant. Excessive
lubricant will throw off into contact points.
:
,
2. Position support on breaker plate and install lock
screw leaving slightly loose for later adjustment..
3. Plug breaker arm wire in.
4. Adjust breaker point gap to ,016”.
/
DWELL ANGLE ADJUSTMENT
1. Connect dwell meter.
2. Remove distributor cap. Remove rotor. Loosen
breaker point set screw approximately
l/8 turn.
3. Insert screwdriver in notch of stationary breaker
point. Observe dwell meter while cranking engine.
Twist screwdriver as required to obtain a reading of
50 degrees plus or minus 3 degrees.4. Tighten breaker point set screw, then recheck
dwell.
5. Install rotor and cap.~Start engine and recheck
dwell. It is important that dwell be rechecked, as
instal~lation of rotor and cap will sometimes change
the dwell angle.
IGNITION TIMING ADJUSTMENT
Preliminary Timing (Engine Won’t Run)To time the ignition on any engine which will run,
use subparagraph b only. However, if the timing of
an engine is completely off, the following procedure
must first be used to get the engine to run.
1. With rocker arm cover removed, rotate crankshaft
in a clockwise direction until both valves for No. 1
cylinder are closed and the timing marks line-up.
(Valves are completely closed if rocker arms can be
“rocked” slightly.)
2. Install distributor in engine so that vacuum ad-
vance unit is in original position and notch in dis-
tributor rotor lines-up with notch in housing. See
Figure lC-3. If distributor does not seat in engine
block., turn distributor shaft so that rotor points
about 20 degrees clockwise from distributor timing
notch
(see Figure lC-18), then press lightly on dis-
tributor housing while cranking engine with starter.
After oil pump tang snaps into slot in distributor
shaft, start timing again from Step 1, leaving dis-
tributor installed.
Figure lC-3 Rotor Position for Filing No. 1 Cyliqder
3. Install distributor clamp and bolt, leaving bolt just
loose enough to permit movement of distributor. In-
stall distributor primary wire.L

IGNITION SYSTEMlC-214. Rota&distributor counterclockwise slightly until
contact pbints just start to open. This must be done
very carefully or engine will not start.
5. Install distributor cap. Make sure spark plug wires
are correctly installed in distributor cap, through clip
and on spark plugs.
Finish TimingIContact boint gap
(.016” at widest gap) or dwell 50
degrees plus or minus 3 degrees should always be
checked before adjusting ignition timing.
1. Connekt timing light to No. 1 spark plug.
2. Disconnect and plug vacuum advance unit and
retard u$it hoses.
3. Connect a tachometer from distributor side of coil
to
groun$l.4. Start dngine. Set idle speed to 900 RPM.
5. Rotate distributor as necessary to align timing
marks. T;ming mark is a steel ball embedded in the
flywheel and a pointer in a window in the right fly-
wheel housing. See Figure lC-4.:Figure lC-4 Ignition Timing Marks
6.
Tightq clamp bolt securely and recheck timing
mark ahgnment.
7. Reconnect vacuum hoses and adjust engine idle
speed
an: mixture.
IGNlTlOFj WIRE INSPECTION
1. The c$il and spark plug wires are of a specialresistance type. These secondary ignition wires
reduce television and radio interference.
2. Wipe ignition wires with a cloth moistened with
solvent and wipe dry. Bend wires to check for brittle,
cracked or swollen insulation. Defective insulation
will permit missing or cross-firing of spark plugs,
therefore any defective wires must be replaced.
3. If wire insulation is in good condition, clean any
terminals that are corroded and replace any termi-
nals that are broken or damaged. Terminals must tit
tight on spark plugs and in distributor cap.
4. Replace any hardened, cracked or loose cap nip-
ples or spark plug boots.
5. Check resistance of each wire from contact inside
distributor cap to spark plug or coil terminal. Re-
place any wire having over 10,000 ohms resistance
reading. See Figure lC-5.
Figure fC-5 Checking Ignition Wire Resistance
CHECK IGNITION OUTPUT
1. Disconnect secondary coil ivire so that engine will
not start. Connect a voltmeter from the battery side
of the coil primary to ground and check voltage
while engine is cranking. Reading should be 10 volts
or more. Low reading could be caused by a defective
battery, a discharged battery, high starter current
draw, a bad connection in the starter circuit or a bad
connection in the primary ignition circuit.
2. Connect an oscilloscope according to manufac-
turer’s instructions. Disconnect coil wire. Crank en-
gine and read coil output voltage. Reading should
exceed 20 KV (20,000 volts).

lC- 22 1973 OPEL SERVICE MANUAL j
3. Start engine and disconnect a wire from a spark
plug. Read output voltage of disconnected spark
plug circuit. Reading should exceed 20 KV
(20,poO
volts).I
CHECK DISTRIBUTOR
!1. Clean distributor cap and inspect it for cracks or
tracking. Inspect inner segments for erosion and
outer sockets for corrosion.
2. Clean and inspect ignition wires. Make sure resist-
ance of each wire is less than 10,000 ohms. Replace
any defective spark plug boots or distributor
capnipples. See paragraph lC-12.
3. Inspect breaker points and replace if necessary.
Adjust breaker point gap to
,016 inch with rubbing
block on peak of cam lobe or check dwell and adjust
if not 50 degrees plus or minus 3 degrees. 4. Check
dwell variation by reading dwell at idle and at 3000
RPM. Dwell must not vary more than 3 degrees.
Excessive variation means distributor shaft, cam or
breaker plate are worn or damaged--overhaul dis-
tributor and replace defective parts.
5. Check distributor condenser for a minimum series
resistance and insulation leakage. Check for a
capacity between
.15 and .20 microfarads.
6. Check total advance (centrifugal and vacuum) at
2500 engine RPM using a timing light having a dial
for reading advance.
(a) The timing marks are aligned with both the
vacuum advance and the vacuum retard hoses dis-
connected and plugged.
Engine idle should be 900 RPM.
(b) Reconnect vacuum hoses. Run engine at
3600RPM and adjust knob until timing marks are
aligned. Read advance on dial. Maximum centrifugal
advance should be between 28-32 degrees.
7. If total advance is out of specifications, check
centrifugal advance only, at
2500 RPM. Discon+ectand plug all vacuum hoses. Maximum vacuum ad-
vance should be l-5 degrees at 4.5-5.0 in. hg.
8. Replace centrifugal or vacuum advance parts as
required to bring distributor total advance within
specifications.
9. Check operation of vacuum retard unit (rear unit)
by first making sure timing marks are aligned with
vacuum hoses disconnected and at slow idle (700
RPM). Then connect vacuum hose to vacuum retard
unit (rear unit). Timing ball should move in a retard
direction (upward).
CHEICK SPARK PLUGS1. Remove spark plugs. If electrodes are badly worn,
discard plugs. If inner or outer porcelain is cracked
or broken, discard plugs.
2. Note color and general appearance of inner end of
spark plug. Brown to grayish
- tan deposits and slight
electrode wear indicate correct spark plug heat
range. Plugs having this appearance may be cleaned,
regapped, tested and reinstalled.
3. Clean spark plugs in a sand blast type cleaner.
Clean only enough to remove deposits, not enough to
wear away porcelain. If deposits are too hard to
remove or if porcelain is glazed, discard plugs.
4. After cleaning spark plugs, clean tiring surfaces of
electrodes with a line file.
5. Test cleaned spark plugs on a pressure tester by
comparing spark of the used plugs with that of a new
plug. Install tested plugs, using new gaskets.
6. If removed spark plugs have excessive carbon foul-
ing and if the car will be driven mostly at low speeds
in city driving, it is advisable to replace plugs with
a hotter plug, AC43FS.
7. If removed plugs show rapid electrode wear or
inner porcelain breakage at low mileage. Check for
a vacuum leak such as a poor manifold to head fit.
8.
Clap spark plugs carefully (new or cleaned) using
a
,030 round wire feeler gage.IC6
Figure lC-6 Distributor Installation

IGNITION SYSTEMlC- 23
9. Install:spark plugs using a 13/16 deep socket, an
extension and a torque wrench. Tighten to 22-29Ib.ft. 1
MAJOR REPAIRDlSTRlBtiTOR OVERHAULDistributbr Removal
1. Remove fuel pump. This is necessary because the
fuel
punp will block the distributor drive gear,
thereby preventing removal of the distributor. See
Figure lC-6.
2. Set No; 1 cylinder at firing point by turning engine
INOTCH IN STATIONARY& -.until cutout in distributor shaft (or rotor tip) points
to notch in distributor housing. See Figure
lC- 7.
3. Ball imbedded in flywheel should be approxi-
mately aligned with pointer in housing. See FigurelC-4.
4. Remove distributor hold-down clamp and remove
distributor. See Figure lC-8. Cover bore in timing
case to prevent foreign material from dropping into
engine. To make reinstallation of distributor easy, do
not rotate crankshaft or oil pump.
Disassembly
1. Remove distributor cap retaining spring clips, and
vacuum control units. See Figure lC-9.
Figure lC-9 Removing Retaining Clips
Figury lC-7 Aligning Shaft Cutout With Notch
Figure lC-8 Removing DistributorFigure lC-10 Removing Retaining Ring

lC- 261973 OPEL SERVICE MANUAL /
SPECIFICATIONSIGNITION COIL
Ignition Coil Number
.,.:.................................................................................................K12 V
Ignition Coil Current Draw, Amperes at 12.5 Volts
EngineStopped
...........:.........................._............................................................................3.8Engine Idling
....................................................................................................................2.3
DISTRIBUTORDistributor TypeNumber:
..................................................................................................JFU4
Total Advance (Centrifugal and Vacuum), Engine Degrees at 3600 R.P.M.
EngineRPM
..................................................................................................................29-37Centrifugal Advance, Engine Degrees and RPM
StartAdvance,atRPM
........................................................................................lOOO-1200MediumAdvance,DegreesatRPM
..............................................................7.5-15at1400Maximum Advance, Dkgrees at RPM
..........................................................28-32 at 3600
Vacuum Advance, Engine Degrees and
In. of Vacuum
Start Advance, at In. of Vacuum
................................................................-5 at 2.9-4.1 In.
Maximum Advance, Degrees at In. of Vacuum
........................................l-5 at 4.5-5.0 In.
VacuumRetard,EngineDegreesatClosedThrottle
............................................................-5CondenserCapacityinMicroFarads
...............................................................................15-.20Breaker Spring Tension in Ounces
..............................................................................14 to 19
Breaker Point Gap in Inches
..............................................................................................,016Dwell angle in Engine Degrees
....................................................................................50 + 3
Firing Order
....................................................................................................................l-32-2
SparkPlug or CoilCable,Max.Resistancti in Ohms
..................................................10,ooO
SPARK PLUGSMake and Model
-Production................I....................................................................AC42FS
Make and Model
- Replacement...................................................................................AC42FS
Ifcarbonfouling
occurs,use.....................................................................................AC43FS
SparkPlugTorqueinLb:Ft.
............................................................................................22-29Spark Plug Gap in Inches
...........................................................................................028-.03 1

i
1 D- 301973 OPEL SERVICE MANUAL
6. Make sure all electrical accessories are turned (lff.
Start engine with battery post adapter switch closed;
open switch as soon as engine
iS: started.
7. Adjust engine speed to 2500 RPM.
8. Turn tester control knob to “LOAD” position
aid
adjust knob to obtain highest possible ammeter r&d-
ing. Output must be 30 amperes minimum. If
outcut
is okay, proceed to voltage regulator test below. j
/.9. If output is low, defect may be in alternator or m
regulator. To eliminate regulator, supply field &-
rent direct to cause full alternat,or output. Unplug
three-way connector from regulator and plug in a
jumper between the red and black leads. See Figure
lD-5. Retest as described in Steps 7 and 8. If output
is still low, generator is faulty and must be
remov&d.
301D5 :
Figure lD-5 Alternator Ouiput Check I
10. If output (using field jumper) is now okay, defect
is in the regulator or wiring harness. Check all wiring
connections. If all wiring is okay, try
replac/~g
regulator; if output now tests okay (without
uslpg
field jumper), you have found the trouble. Always
follow-up with a voltage regulator test.
Test and Adjust Voltage Regulator Setting
1. Always test alternator output first, as describedlin
subparagraph a above. Leave all test
instrumeqts
connected, but make sure field
jumper is removed; if
used.
2. With engine speed at 2500 RPM, turn tester con-
trol
knob to “l/4 OHM” position. Make sure ill
electrical accessories are turned off. After volt&e
reading stabilizes, any reading between 13.5 and 14.5
volts is okay.
3. If voltage reading is out of limits, remove regulator cover and adjust voltage regulator armature spring
tension to obtain a middle reading of 14.0 volts. If
reading fluctuates, voltage contacts are dirty.
4. Replace regulator cover and recheck voltage set- ting. A steady voltage reading between 13.5 and 14.5
volts means voltage regulator is okay.
5. Adjust engine speed to specified idle. Reseal volt-
age regulator cover carefully, using electrical tape.
MAJOR REPAIR
ALTERNATOR OVERHAUL
Always disconnect battery ground cable before mak-
ing any electrical repairs.
Alternator Removal
1. Disconnect battery ground strap.
2. Unplug wiring connector from alternator. 3. Disconnect battery lead from alternator.
4. Remove adjusting brace bolt, lockwasher, plain
washer and nut.
5. Loosen pivot bolt. Push alternator inward and
remove belt from pulley.
6. Drop alternator down and remove pivot bolt, nut,
lockwasher and plain washer.
7. Remove alternator.
Figure 1D-6 Removing Alternator Pulley

CHARGING SYSTEMlD- 35
’Figure lD-25 Installing Diode
I
7. Instail rotor together with drive end frame intostator and assemble generator in reverse order ofdisasse+bly. Make sure marks made during disas-
sembly
+-ire aligned.
8. Insta!l pulley and fan. Tighten nut to 30 lb.ft.
9. Test benerator on test bench, if available. If not,
install alternator on car and test.
Alternator Installation
1. Hold /alternator in position and install pivot bolt,
plain washer, lockwasher and nut finger tight.
2. Install alternator belt.
3. Install adjusting brace bolt, lockwasher, plain
washer and nut finger tight.
4.
Posit& a belt tension gage such as Gage J- 23600Figure 1 D-26 Alternator Installation
on belt. Pull alternator outward until gage reads 45
Ibs., then tighten adjusting brace bolt.
5. Tighten alternator pivot bolt.
6. Connect battery lead to alternator.
7. Plug three-way wiring connector into alternator
and engage safety catch.8. Connect battery ground strap.SPECkICATIONS
ALTERNATOR
35, AMPAlternatorNumberRated
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Kl 14V35AZOOutputinVolts
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14ContinuousRatedOutputinAmperes
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35Test Output in Amperes at
2000 Engine RPM. . . . . . . . ..__.._...........................................23 Min.RksistanceofFieldCoilinOhms
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4.4Resistanceof StatorWindingsinOhms
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26-29AlternatorPulleyNutTorqueinLb.Ft.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
BfltTensioninPounds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
REGULATORRegulatorNumber
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ADl/14V
Regulator Setting in Volts at 2500 Engine R.P.M.
. . . . . . . . . . ..___................................14 f .5