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177
PART 9-2DUAL ADVANCE DISTRIBUTORS . . . . 9-22
9-1
PART91
GENERAL IGNITION SYSTEM SERVICE
Section Page Section Page1 Diagnosis andTesting 9-1 3 Cleaning
and Inspection 9-212 CommonAdjustmentsandRepairs 9-17
CONVENTIONAL IGNITIONSYSTEM
The ignition system consists of aprimary low voltage anda
secondary high voltage circuit Fig. 1.
The primary circuit consists ofthe:
1. Battery.2. Ignition switch.3. Primary circuit
resistancewire.4. Primary windings of the igni
tion coil.5. Breaker points.6. Condenser.The secondarycircuit
consistsof
the:1. Secondarywindings of the igni
tion coil.2. Distributor rotor.3. Distributor cap.4. High
tension wires.5. Sparkplugs.When the breaker points are
closed, the primary or low voltagecurrent flows from the
batterythrough the ignition switch to theprimary windings in the
coil, thento groundthroughthe closedbreakerpoints. When the breaker
pointsopen, the magneticfield built up inthe primary windings of
the coilmoves through the secondarywindings of the coil producing
high voltage current. High voltage currentis producedeach time the
breakerpoints open. The high voltage flowsthrough the coil high
tension lead to
the distributor cap where the rotordistributesit to oneof the
sparkplugterminals in the distributorcap.Thisprocessis repeatedfor
every powerstrokeof the engine.
TRANSISTOR IGNITIONSYSTEM
The permatuned transistor ignitiori system is available on the
430V-8 engine. Figure 2 shows a schematic of the transistor
ignition systern.
The ignition coil primary in the
transistorsystemis designedto draw12 amperespeakcurrent, or
approximately 5.5 amperesaveragecurrent,as indicatedon an
ammeter,in orderto provide high spark plug voltageat the higher
enginespeeds.
The transistor in the system actsas a heavy duty switch or
relay. Itis similar in action to a horn relay,except that it has no
moving parts,and thus acts with very little timelag. The
transistoris connectedbetween the battery andthe coil, andis used
to make and break the coil
GENERAL IGNITION SYSTEM SERVICE . . 9-1PART 9-1 PAGE PART 9-3
PAGE
SPECIFICATIONS 9-27
O DIAGNOSIS AND TESTINGGENERAL INFORMATION
FIG. 1 -Typical Ignition Circuit
-
GROUP 9-IGNITION SYSTEM
primary circuit.Thedistributorcontrolsthetransis
tor. The 8-ohm resistor, connectedbetweenthe distributorandthe
transistor in the wiring harness,limitsthe transistor control
current anddistributor point current to 0.5 ampere. The low
distributor point current eliminatespitting andgiveslongdistributor
point life.
The distributorcondenserhasbeenincreasedin value to 2 mfd, and
islocatedin the amplifier assembly.Asin the standard ignition
circuit, itabsorbshigh inductive energyduringinitial distributor
point opening.However, it no longerhas anyeffecton the distributor
points as the transistor effectively isolates the pointsfrom the
coil.
The amplifier assemblyFig. 3 ismountedunderan
insulatedcoveronthe left front fender inner panel.
A ceramic ballast resistor ismountedwith the amplifier, a
tachometer connectorblock is mountedon the firewall anda cold start
relayis mountedon the right, front fenderin the engine
compartment.
A 2-amperefuse in the collectorto tachometerblock lead
preventsthe transistor from being damaged
FIG. 3-Amplifier
by the applicationof externaldevicesother than normal
testingequipment.
The cold start relay contacts arenormally closed and they are
connected into the circuit only duringthe start cycle. When the
starterrelay is closed,the cold startrelay isactuatedand opens its
contacts. If,during starting, the available voltagedrops below 10.5
volts, the relaycontacts close, thus by-passing the0.33-ohm
resistor in the ballast resistor block, and applying full available
voltage to the system.
The tachometerblock is used to
connecta tachometeror other testequipmentinto the circuit. Do
notconnect test equipment into thecircuit in any other manner,
orreadings will be inaccurate anddamage may occur to the
transistor, or change its operating characteristics.
Connectthe tachometerred leadto the tachometerblock red
terminalandblacklead to the blackterminal.
TROUBLE ISOLATION
CONVENTIONAL IGNITIONSYSTEM
Ignition systemtroublesarecausedby a failure in the primary/or
thesecondarycircuit or incorrect ignition timing. If an engine
troublehasbeentracedto the ignition systern from the"Engine
TroubleDiagnosis Guide", the trouble can befound by performingan
ignition system test on a scope or by wtherisolating the trouble to
the primaryor secondarycircuit as follows:
1. Remove the coil high tensionleadfrom the distributor cap.
2. Hold the high tension lead approximately Yi; inch from the
cylinder head.
9-2 178
FIG. 2-Transistor Ignition System Schematic
B1717-C
81844-B
Assembly
-
PART 9-1 -GENERAL IGNITION SYSTEM SERVICE 9-3
3. With the ignition switch on,crank the engine and check for
aspark.
If the spark is good, the troublelies in the
secondarycircuit.
If there is no spark or a weakspark, the trouble is in the
primarycircuit, coil to distributor high tension leador the
coil.
PrimaryCircuit. A breakdownorenergy loss in the primary
circuitcanbe causedby:
1. Defective primary wiring.2. Burned or improperly adjusted
breakerpoints.3. A defectivecoil.4. A defectivecondenser.
SecondaryCircuit. A breakdownor energy loss in the
secondarycircuit can be causedby:
1. Fouled or improperly adjustedsparkplugs.
2. Defective high tension wiring.3. High
tensionleakageacrossthe
coil, distributor cap or rotor.
TRANSISTOR IGNITIONSYSTEM
Do not use any testing procedures or conventional short
cutsother than those listed below, orextensivedamagecan result to
thesystem.
Ignition troubles are causedby afailure in the primary or
secondarycircuit, or incorrect ignition timing.Isolate the trouble
as follows:
1. Remove the coil high tensionlead from the distributor
cap.
2. Hold the high tension leadapproximately ¼ inch from
thecylinder heador good ground.
3. With the ignition switch on,crank the engine and check for
aspark. The engine may be crankedby the conventionalmethod of
running a jumper wire from the batterypositive terminal to the "S"
terminalof the starter relay, after disconnecting the red and blue
lead atthe relay.
If the spark is good, the troublelies in the secondaryhigh
voltagecircuit. If there is no spark or aweak spark, the trouble is
in theprimary low voltage circuit.
Primary Circuit. A breakdownot energyloss in the primary
circuitcan be causedby:
1. Defectiveprimary wiring.2. Improperly adjusted, contami
natedor defectivedistributor points.3. Defectiveamplifier
assembly.SecondaryCircuit. A breakdown
or energyloss in the secondarycircuit can be causedby:
1. Fouled or improperly adjustedspark plugs.
2. Defectivehigh voltagewiring.3. High
voltageleakageacrossthe
coil, distributor cap or rotor.
PRIMARY CIRCUIT TESTS
CONVENTIONALIGNITION SYSTEM
A complete test of the primarycircuit consists of checking the
circuit from the batteryto the coil, thecircuit from the coil to
ground,andthe starting ignition circuit.
Excessive voltage drop in theprimary circuit will reducethe
secondary output of the ignition coil,resulting in hard starting
and poorperformance.
Battery to Coil Test
PROCEDURE
1. Connectthe voltmeter leads asshown in Figs. 4 and 5.
2. Install a jumper wire from thedistributor terminal of the
coil toa good ground on the distributorhousing.
3. Turn the lights and accessoriesoff.
4. Turn the ignition switch on.
RESULTS. If the voltmeter reading is 6.9 volts or less, the
primarycircuit from the battery to the coilis satisfactory.
FIG. 4-Battery to CoilTest- Rotunda Tester
179
Sun
82001-A
FIG. 5-Battery to CoilTest-Sun Tester
If the voltmeterreadingis greaterthan 6.9 volts, check the
following:
1. The batteryandcablesfor looseconnectionsor corrosion.
2. The primary wiring for worninsulation,brokenstrands,and
looseor corroded terminals.
3. The resistancewire for defects.4. The relay to ignition
switch for
defects.
Ignition Switch Test
PROCEDURE
1. Connectthe voltmeter leads asshown in Figs. 6 and 7.
2. Install a jumper wire from thedistributor terminal of the
coil to agood groundon the distributor body.
3. Turn all of the accessoriesandlights off.
4. Turn the ignition switch on.
RESULTS. If the voltmeterreading is 0.3 volt or less, the
ignitionswitch andthe relay to switch wireare satisfactory.
If the voltmeter readingis greaterthan 0.3 volt, either the
ignitionswitch and/orthewire aredefective.
Resistance Wire Test
PROCEDURE
1. Connectthe voltmeter leads asshown in Figs. 8 and 9.
82000A 2. Install a jumper wire from thedistributor terminal of
the coil to agood groundon the distributorhousing.
-
9-4 GROUP 9-IGNITION SYSTEM 180
ITB2002-A
FIG. 6-ignition Switch FIG. 8-Resistance Wire FIG. lO-Starting
IgnitionTest -Rotunda Tester Test -Rotunda Tester Circa it
Test-Rotun do Tester
3. Turn all of the accessoriesandlights off.
4. Turn the ignition switch on.
RESULTS. If the voltmeterreading is 6.6 volts or less, the
resistancewire is satisfactory.
If the voltmeter readingis greaterthan 6.6 volts, replacethe
resistancewire.
FIG. i-Ignition SwitchTest-Sun Tester
Starting Ignition Circuit Test
PROCEDURE
1. Connect the voltmeter leads asshown in Figs. 10 and 11.
2. Disconnectand groundthe coilto distributorhigh tensionleadat
thedistributor.
3. With the ignition switch off,crank the engine by jumping
the
ignition switch at the solenoid whileobservingthe voltage
drop.
RESULTS. If the voltage dropis 0.1 volt or less, the starting
ignition circuit is satisfactory.
If the voltage drop is greaterthan0.1 volt, clean andtighten the
terminals in the circuit or replace thewiring as necessary.
FIG. li-Starting IgnitionCircuit Test-Sun Tester
Red.
+
82004-A 82006-A
Sun
Black
B2003-A 82005-A
FIG. 9-Resistance WireTest-Sun Tester
B2007-A
-
PART 9-i -GENERAL IGNITION SYSTEM SERVICE 9-5
Coil to Ground Test
PROCEDURE
1. Connectthe voltmeter leads asshown in Figs. 12 and 13.
2. Close the breakerpoints.3. Turn all lights and
accessories
off.4. Turn the ignition switch on.
RESULTS. If the voltmeterread-
FIG. 12-Coil to GroundTest-Rotunda Tester
FIG. 13-coI to GroundTest-Sun Tester
ing is 0.1 volt or less, the primarycircuit from coil to ground
is satisfactory.
If the voltmeterreadingis greaterthan 0.1 volt, test the voltage
dropof each of the following:
I. Coil to distributor primarywire.
CONDITION CAUSED BY
Any discolorationother thana frostedslategrey shall be
consideredasburnedpoints.
EXCESSIVE METALTRANSFER OR PITTING
Incorrect alignment.Incorrect voltage regulator setting.Radio
condenserinstalled to thedistributor
side of the coil.Ignition condenserof improper
capacity.Extendedoperationof the engineat speeds
other thannormal.81443-B
FIG. 14-Breaker Point InspectionNO SPARK AT COIL
WITH IGNITION ON AND COLD START RELAY DISCONNECTED,CONNECT DWELL
METER TO TACH BLOCK AND CRANK ENGINE
0° DWELL 0° TO 45° DWELL 45° DWELL
1.
2.
POINTS ARE CONTAMINATED TROUBLE 1. NO POWER FROM IGNITIONOR ARE
NOT CLOSING. I IS NOT IN SWITCH.OPEN CIRCUIT IN DISTRIBUTOR I
TRANSISTOR 2. POINTS ARE NOT OPENING.LEAD TO AMPLIFIER. CIRCUIT 3.
AMPLIFIER IS MALFUNCTIONING.
181
2. The movablebreakerpoint andthe breakerplate.
3. The breakerplate and the distributor housing.
4. The distributor housing, andengineground.
Breaker Points. The breaker
DISCONNECT DISTRIBUTOR LEAD AND CRANK ENGINE
0° DWELL
L POINTS ARE NOT OPENING
45° DWELL
1. NO POWER FROM IGNITION SWITCH.
L2 AMPLIFIER IS MALFUNCTIONiNG.
CONNECT DISTRIBUTOR LEAD. CONNECT VOLTMETERTO RED TERMINAL OF
TACH BLOCKAND TO GROUND. CRANK ENGINE.
NO VOLTAGE
82009-A J NO POWER FROM IGNITION SWITCH J
STEADY VOLTAGE
AMPLIFIER IS MALFUNCTIONING J81890-A
FIG. l5-Transistor Ignition System Test Procedures
-
9-6 GROUP 9-IGNITION SYSTEM
point assemblyconsists of the stationary point bracket
assembly,breaker arm and the primary wireterminal.
Breakerpointsshouldbeinspected,cleaned and adjusted as
necessary.Breaker points can be cleaned withchloroform anda stiff
bristle brush.Replacethe breakerpoint assembly
* if the contactsare badly burnedorexcessivemetal
transferbetweenthepoints is evident Fig. 14. Metaltransferis
consideredexcessivewhenit equalsor exceedsthe gap setting.
Coil. The coil should be testedfollowing the instructions
under"Ignition SystemTests".
Condenser.The condensershouldalso be testedfollowing the
instructions under "Ignition SystemTests".
TRANSISTORIGNITION SYSTEM
When diagnosisproceduresisolatetrouble to the primary circuit,
makethe following tests to locatethe defective items. Do not use
any otherprocedure, conventional short cut,or connect test
equipment in anyother manner than that describedor
extensivedamagecan be causedto the transistor ignition
system.Figure 15 shows the transistorignition system tests in
outline form.
Disconnectthe cold start relay.Connectadwell meterto
thetachometer block. Connect the black leadto the black terminal
and the redlead to the red terminal. Turn theignition on and crank
the engine.Observethe dwell meter reading.
0° Dwell. A dwell reading of 0°indicates:
1. The distributor points are contaminated or are not
closing.
0° to 45° Dwell. A dwell readingbetween0° and 45° indicates:
1. The transistor andthe primarycircuit are functioning
properly.
2. The trouble could be in thesecondarycircuit.
45° Dwell. A dwell reading of45° indicates:
1. No power from the ignitionswitch.
2. The distributor points areclosed and not opening.
3. Defective amplifier assembly.To determinewhich of the
three
items listed are causing the troubleproceed as follows:
Disconnectthe distributor lead atthe bullet connector,and crank
theengine. If the dwell meter indicates0° dwell, the distributor
points are
not opening. If 45° dwell is indicated,theamplifier is
malfunctioningor there is no power from the ignition switch.
Use a voltmeter or test light todetermineif the
transistoramplifierassembly is at fault. Connect thevoltmeterto
thered-greenleadterminal of the ballast resistor and
toground.Crankthe engine.
If a steady indication of voltageis obtained, the trouble is in
theamplifier. Absence of any voltageindication on the voltmeter
showsthere is an opencircuit, or no powerbetweenthe ignition switch
and theamplifier. The ballast resistor couldbe defective.Replaceit
with aknowngood ballast resistor,and repeatthetest.
If the test procedure indicates adefectiveamplifier, replaceit
with aknown good amplifier, and proceedas follows:
Connect the distributor high tension lead at the bullet
connector.Then, with the cold start relay disconnectedand the dwell
meterconnected to the tachometer block,crank the engine and
observetheindicateddwell. A readingbetween0° and 45° indicates
satisfactoryignition; thus, the amplifier is atfault.
If the dwell reading is still 450,
thewiring from the amplifier throughthe ballast resistorto the
coil is defective. Replacethe defective item.
SECONDARY CIRCUIT TESTS
The following procedure is usedon both ignition systems.
PRELIMINARY CHECKS
1. Removethe coil to distributorhigh tensionlead
andthesparkplugwires from the distributor cap andfrom the spark
plugs. Inspect theterminals for loosenessand corrosion. Inspect the
wires for breaksand cracked insulation. Replace
alldefectivewiring.
2. Cleanthe inside of the distributor cap, and inspect it for
cracks,burned contacts,permanentcarbontracks or a defectivecenter
carbonbrushelectrode.Removedirt or corrosion from the
sockets.Replacethecap if it is defective.
3. Inspect the rotor for cracksordefects. Replace the rotor if
it isdefective.
SECONDARY HIGH TENSIONWIRES
wires connectingthe distributor capto the sparkplugs and the
wire connecting the center terminal of thedistributor cap to
thecenterterminalof the ignition coil.
These wires are the radio resistance-typewhich filter out the
highfrequency electrical impulses thatarethe sourceof ignition
noiseinterference.The resistanceof each wireshould not exceed
24,500 ohms.When checking the resistanceofthewires for setting
ignition timing, do not puncture the wireswith aprobe. The probe
may causea separation in the conductor.
At regular intervals, clean andinspect the wires for
crackedinsulation and loose terminals..Repair orreplace the wires
as required. Asparkplug wire set is available forservice.
When removing the wires fromthe spark plugs,grasp the mouldedcap
only. Do not pull on the wirebecausethe wire connection insidethe
cap may become separatedorthe weather seal may be damaged.
Spark Intensity
1. Disconnect a spark plug wire.Check the spark intensity of
onewire at a time.
2. Install a terminal adapter inthe terminal of the wire to
bechecked. Hold the adapterapproximately j’iA inch from the
exhaustmanifold andcranktheengine, usinga remotestarter switch. The
sparkshould jump the gap regularly.
3. If the sparkintensity of all thewires is satisfactory, the
coil, condenser, rotor, distributor cap andthe secondary wires are
probablysatisfactory.
If the spark is good at only somewires, perform a high
resistancetestof the faulty leads.
If the spark is equal at all wires,but weak or intermittent,
make ahigh resistancecheck of the coil,distributor cap and the coil
to distributor high tension wire. Followthe instructionsof thetest
setmanufacturerwhen making the tests.
On the transistor ignition, donot test the coil on a coil
tester,as inconclusiveresultswill be obtained due to the very low
coilprimary inductance. Substitute aknown good coil and perform
theprimary circuit tests.
SPARK PLUGS
182
The secondarywires include theClean, inspect and gap the
plugs
following the instructionsin Sections
-
9-7PART 9-1--GENERAL IGNITION SYSTEM SERVICE
2 and3. After the propergap is obtained, checkthe plugs on a
testingmachine.Comparethe sparkingefficiency of the cleanedand
gappedplug with a new plug. Replacetheplug if it fails to meet 70%
of thenew plug performance.
Test the plugs for compressionleakage at the insulator seal.
Applya coating of oil to the shoulderofthe plug where the insulator
projectsthrough the shell, andto the top ofthe plug, where
thecenterelectrodeand terminal project from the insulator. Place
the spark plug underpressurewith the tester’s high tension wire
removed from the sparkplug. Leakage is indicated by airbubbling
through the oil. If the testindicates compression leakage, replace
the plug. If the plug is satisfactory, wipe it clean.
IGNITION TIMING
Incorrect ignition timing can becausedby:
1. Timing incorrectly adjusted.2. Distributor bushing and/
or
shaft worn, or a bent distributorshaft.
3. Defectivevacuum advancesystem.
4. Defectivecentrifugal advance.
IGNITION SYSTEM TESTS-ROTUNDA TESTERS
TEST CONNECTIONS-RE-235,RE-651, AND RE-881
The test connectionsfor the RE-235 testerareshown in Fig. 16,
thetest connections for the RE-651teter are shown in Fig. 17, and
thetest connections for the RE-881tester areshownin Fig. 18.
1. With the testerturned off, plugthe power plug into a proper
ACoutlet.
2. Connect the green lead to thedistributor terminalof the
coil.
On a car equipped with atransistor ignition, connect thisgreen
lead to the terminal on thered side of the tachometer block.
3. Remove the No. 1 plug wirefrom the distributor cap, place
theblue pickup in the cap andplacetheplug wire in the pickup.
4. Now connect the black lead toa good ground.
If the car has a transistor ignition, connectthe black leadto
theterminal on the black side of thetachometerblock.
6. If the engine timing is to bechecked, plug the timing light
intoits socket.
The following stepspertainto theRE-651 and RE-881
testersonly.
7. Disconnect the battery wirefrom the regulator and place it
inthe knob end of the 100 ampereshunt.
8. Place the spade terminal fromthe 100 ampereshuntandthe
yellowlead on the battery terminal of thevoltageregulator.
9. Turn thegroundpolarity switchto the minusposition. On
theRE-881tester, turn the volts switch to the 20volt position.
POINT RESISTANCE TEST
RE-651 Tester
1. Remove and ground the hightension wire from the centerof
the
distributor.2. Turn the volts switch to the
point resistance PT. RES. position. The points should be
closedforthis test. If the breaker points areopen, the meterwill
readthe batteryvoltage 0 to 40 scale.
3. "Bump" the starter with thestarter switch until the
voltmeterpointer decreasesto the lowest reading in the black zone.
On a carequipped with a transistor ignition, this bumping is done
byjumping between the "5" terminalof the solenoid and the
batterywith the ignition switch off andthe coil lead brown wire
disconnected from the solenoid.
4. Depress the PT. RES. pushbutton.
5. The voltmeter pointer shouldreadwithin the 12V areaas
shown
183
FIG. 16-Rotunda RE-235 Test Connections
B 1991-A
5. Clip the red pickup over thecoil-to-distributor high tension
wire.
-
9-8 GROUP 9-IGNITION SYSTEM
in black on the meter dial. If not,check for incorrect breaker
pointspring tensionor for burnedor pittedpoints.
6. Connectthe high tensionwireto the distributor.
RE-881 Tester
1. Remove and ground the hightension wire from the centerof
thedistributor.
2. "Bump" the starter with thestarter switch to close the
breakerpoints. This will be indicatedby theloweht reading on the
voltmeter. On
a car equipped with a transistorignition system, the starter
isbumped by jumping between the"S" terminal of the solenoid andthe
battery, with the ignitionswitch off and the coil lead brownwire
disconnectedfrom the solenoid.
3. The voltmeter pointer shouldread in theblack OK PT.
RES.area.If it doesn’t, check for improperbreakerpoint spring
tension or forburnedor pitted points.
4. Connect the high tension wireto the distributor.
Disconnect the vacuum line. Ifnecessary,clean and mark the
desired timing mark.
RE-235 Tester
1. Start the engine and allow itto warm up.
2. Operate the engine at the specified idle speedand point the
timinglight toward the pointer. The desired timing mark should line
upwith the pointer.If it doesn’t, loosenthe distributor hold down
bolt androtate the distributor until the mark
184
IANY GOOD GROUND
FIG. 17-Rotunda RE-651 Test Connections
81 992-A
IGNITION TIMING
-
PART 9-1 -GENERAL IGNITION SYSTEM SERVICE 9-9
cv.
KV
25
10A
20
‘15. PUG
* B 10
* C D ,0
DWELL-II I I
30 25 20 15 8CYL.
FIG. 19-NormalSuperimposed Primary Pattern
FIG. 18-Rotunda RE-881 Test Connections
lines up with the pointer. Nowtightenthehold down bolt
andcheckthe timing.
RE.651 Tester
1. Turn the rpm selector to the1000 position.
2. Depress the advance timingpushbutton.
3. Start the engineand allow it towarm up.
4 Operatethe engineat thespecified idle speed.
5. Turn the advance knob untilthe ignition advancemeter
reads0°.
6. Point the timing light towardthe timing pointer. The
desiredtiming mark should line up with thepointer. If it doesn’t,
loosen the dis
tributor hold down bolt and rotatethe distributor until the
desiredtiming markandpointerline up. Tightenthe distributor hold
down bolt andcheckthe timing.
RE-881 Tester. The method oftesting is the same as the
RE-65ltester with the exceptionof Step Iwhich should for theRE-881
read"turn the rpm selector to the 800position."
SUPERIMPOSED PRIMARYPATTERN
Procedure
RE-235 TESTER
1. With the engine running at
1000 rpm, turn the test selectorswitch to the primary PR!.
position.
2. Adjust the parade control toposition the left end of the
patternat the left verticalline on the screen.
3. Adjust the expand control sothat the right end of the
patternisat the right vertical line on thescreen.
RE-651TESTER
1. Turn the rpm selector to the5000 position. Start the
engineandadjustit to 1000 rpm.
2. Depressthe PRI pushbuttononthe console panel.
3. Adjust the paradeand expandcontrols to position the left end
ofthe pattern at the left vertical lineon the screenand the right
end ofthe pattern at the right vertical lineon the screen.
RE-881 TESTER. The test procedurefor the RE.-881 is the same
81993-A as the test procedurefor the RE-651except for the
setting of the rpmselector. For the RE-881 tester, therpm selector
is turned to the 1600position.
Results. A normal test pattern isshown in Fig. 19.
Point A indicates the spark plugline which is the time when
thepoints open. At B, the coil energy isusedup sufficiently so that
the plugno longer fires and only the energystoredin thebreakerpoint
condenserremains.This coil/condenseroscillation which is
indicatedin thepatternbetweenB and C is completelyusedup at C which
is the points closemark. The portion of the patternbetweenC andD is
the points closetime, which is cam angle or dwelltime. At D, the
points again openand the firing cycle repeats.
If points A and C are below the
185
0
81994-A
-
9-10 GROUP 9-IGNITION SYSTEM
horizontal 0 line, the batterypolarity is incorrect.This could
be causedby a battery that is either installedincorrectly or
improperly charged,causing a polarity reversal.
If the firing line is not below the0 line and there are no
oscillationsat point C, there is an opencircuitat the coil high
tension tower. Thiscould be causedby a broken wireinside the coil
tower, or a brokencenter contact on the distributorrotor.
If the dwell time is too short, thebreaker points are
incorrectly setthe larger the gap, the smaller thedwell.
If point A is at a reducedheight,andthe distanceto B is short or
nonexistent,and theoscillationsat pointC are reducedin height,
there is a
KV
lv - - - - - - - -
- - - - - - -
BD
50L. ..L
oLJ
20Li..
6CYL,
¶ 32’52O rr jiFIG. 20-Normal
LUG
*juKV
*
A
L
F;;5
0
Superimposed Secondary Pattern
high resistancein the coil primarycircuit. This could be
causedby afouledplug, defectiveignition switch,or a bad wire or
connection.If thescopepatternis still the sameafterthe above
ignition parts havebeencheckedandprovensatisfactory,runthe 15 KV
testto checkfor a gasketleak or a lean fuel mixture.
If point A is at a greatly reducedheight and there are no
oscillationsat point B, the coil has a defectiveprimary winding or
the condenserhasan excessiveseriesresistance.
If there is a variation at points Cand D, the cam lobes are
uneven,the distributor shaft is bent, or thedistributor bushingsare
worn.
SUPERIMPOSED SECONDARYPATTERN
Procedure
RE-235TESTER
1. With the engine running at1000 rpm, turn the test
selectorswitch to thesecondarySEC. position.
2. Adjust the parade and expandcontrols so that the left end of
thepatternis at the left vertical line onthe screenand the right
end of thepattern is at the right vertical lineon the screen.
RE-651AND RE-881TESTERS.The procedureis the same as
theprocedurefor the primary superimposed pattern except the
SEC.pushbutton is depressedinstead ofthe PR! pushbutton.
Results.A normal test patternisshownin Fig. 20.
Point A is the points open time.The height of the patternat
point Aindicates the high tension voltagerequiredto overcomethe
sparkpluggapresistance.
Point B is the plug firing line.Notice that this portion of the
pattern is quite thick. Rememberthatthis pattern is actually 8
firing patternssuperimposedoneon top of theother. This increasein
thickness ofthepatternat B is causedby slightvariationsin theplug
gap, distributorrotor gap and slight differences inthe resistanceof
the individual sparkplug circuits.
The patternarea between pointsC and D shows the
coil/condenseroscillations to be correct. No point
81996-A bounceat D indicatescorrectbreaker point spring
tension.
The few so called dampedoscillations appearingat D arenormal
andare causedby the surge of currentthrough the coil primary
windingwhen the breakerpoints first close.
This current levels off and decreasesslightly toward the
pointsopen position at E as indicatedbythe slight downward slope of
thecurve at about the 15° mark on thecamangle scale.
To observe the coil/condenseroscillations and the
dampedoscillations at D’ in greaterdetail, adjustthe expandcontrol
so that the pattern area betweenpoint C and D’nearly fills the
screen.
If there is erratic action at pointsC and D, and there is a
blotchabovepoint E, thebreakerpoints areburnedor badly pitted.
If the length of B is reducedandthe patternbetweenC and D is
notsuperimposed,there is a seriesgapin the coil high tension tower
orwire.
If the line at B is sloping downward greatly resistor plugs
willcausea slight slope, there is a highresistancein the spark plug
wires,distributor cap or rotor.
.
10
20 6CYL.40 30I_J.I
*
0I I5 20 15 8 CYL
FIG. 21-is KY PatternIf point D1 is varying erratically,
the distributor is badly worn. If thisvariationis definite
insteadof erratic,the advancemechanismin the distributor is
defective.
If the dwell line betweenpointsD1 and E is not the smooth
lineshown, there is a looseconnection inthe primary circuit. Check
the primary circuit for loose connections,damagedwires or
adefectivestarterswitch.
15 KV PATTERN
Procedure
RE-235TESTER. With the engineoperatingat 1000 rpm, turn the
testselectorswitch to the 15 KV position. Adjust the
expandandparadecontrols to produce the patternshown in Fig. 21.
RE-651 TESTER. With the rpmselectorat the 5000 position
andtheengine operatingat 1000 rpm, depressthe 15 KY
pushbutton.Adjustthe expandand paradecontrols
toproducethepatternshownin Fig. 21.
RE-881 TESTER. With the rpmselectorat the 1600 position
andtheengine operatingat 1000 rpm, depressthe 15 KY
pushbutton.Adjustthe expand and paradecontrols
toproducethepatternshownin Fig. 21.
Results. A normal 15 KV patternis shownin Fig. 21. The spark
plugline A for the No. 1 spark plugis on the extremeright hand side
ofthe screen.The remainderof the No.1 firing patternis on the left
sideofthe screen. The remainder of thepatternsareshownfrom left to
rightin their firing order.
With the exception of the No. 1spark plug line which should
beshorter than the others, the patterns should be similar. If oneof
thepatternsdiffers from the others, adjust the
expandandparadecontrols
186
25
* -
B1995-A
-
187
‘30cv KV
* 25
10 ‘20
PLUGis
Be 1;
FIG. 22-30 KY Pattern81997-A
until that patternfills the screeninthe samemannerasin the
secondarytest Fig. 20.
The following list of symptomswill refer to Fig. 20.
If the points open line A ishigher than the rest and the
plugfiring line B is sloped downwardat an unusuallylarge slope,
there isexcessiveresistancein the high tension wire to that
cylinder or in thedistributor cap.
If the points openline A is lowand the firing line B is long
andnearly straight, the spark plug isshortedout.
If the points open line A is lowand the firing line B is long
andwide, the spark plug gap is out ofadjustment.
If there are no oscillations atpoints C or D, the coil
primarywindings are partially shorted.
If the points open line A andthe oscillations at point D are
bothdisplacedto the right on all cylinders, checkthe breaker
points.
all of the points openlines Aareat varied heights, check the
idleadjustmentof thecarburetoralwaysadjust the idle mixture on the
richside.
30 KV PATTERN
Procedure
RE-235TESTER. With the enginerunning at 600 rpm, turn the
testselectorswitch to the 30 KY position. Adjust the expand
andparadecontrols to produce the patternshown in Fig. 22.
RE-651 TESTER. With the rpmselectorat the 5000 position
andtheengineoperatingat 600 rpm, depressthe 30 KV pushbutton.Adjust
theexpand and paradecontrols to produce the patternshown in Fig.
22.
RE-88l TESTER. With the rpmselectorat the 1600 position and
theengineoperatingat 600rpm, depress
the 30 KY pushbutton. Adjust theexpandand paradecontrols to
produce the pattern shown in Fig. 22.
Results. A normal 30 KV patternis shown in Fig. 22. The
sparkplugline A for the No. I spark plugis on the extremeright hand
side ofthe screen. The remainder of theNo. I firing pattern is on
the leftsideof the screen.The remainderofthe patterns are shown
from left toright in their firing order.
Notice the averageheight of thesolid part of the points open
line.Increasethe speedof the engineandnotice the height of the
dottedlines.The difference is the required ignition output under
load. The maxirrium output should be between13.5and 15 KV.
If the maximum for one or moreof the plugs is above 15 Ky,
checkthe complete circuits of theplugs for any trouble that
wouldc:ause this resistance.If the maximum does not increase during
theincrease in engine speed,check for
a fouled or improperlygappedsparkplug or for very low
compression.
Remove the high tension wire atthe distributor cap for any
plugexcept No. 1. Notice the changebetweenthe averagepoints
openlineand the points open line of thecylinder with the high
tension wireremoved. This height difference isthe coil reserve. The
coil reserveshould be at least 30% of the maximum output. If it is
less than 30%,replacethe coil.
Remove and do not ground onespark plug wire at the spark plug.If
a plug firing line shows up on thescope for that cylinder, check
theplug wire and distributor cap forbad insulation.
IGNITION SYSTEM TESTS-SUN 900 TESTER
TEST CONNECTIONS
Most of the ignition system canbetestedby using theSun 900
ScopeMotor Tester.Make the connectionsas follows Fig. 23.
PART 9-1 -GENERAL IGNITION SYSTEM SERVICE
TEST LEADS
9-11
FIG. 23-Sun 900 Tester Connections
-
9-12 GROUP 9-IGNITION SYSTEM
1. Plug the power cord into aproper outlet.
2. Turn the AC masterswitch tothe ON position.
3. Turn the Tach-Dwell selectorswitchto the calibratorCAL.
position and adjust the dwell calibratoruntil the meter pointer
readson theSET LINE.
4. Turn the Tach - Dwell rpmswitch to the 5000 position.
5. Connect the Tach-Dwell leads;connect the RED insulator lead
tothe primary distributor lead at thecoil. Connectthe BLACK
insulatorlead to a good ground.
On a carequippedwith a transistor ignition system,connecttheRED
insulator lead to the REDside of the tachometer block andthe BLACK
insulator lead to theBLACK side of the tachometerblock.
6. Connectthe trigger pickup intothe circuit of the first spark
plugin thefiring order.
7. Turn the Voltage Leakageunitcontrol counterclockwise to
theTIMING position.
8. Connect a jumper lead fromthe distributor primary to a
goodground.
9. Set the Voltage Leakageswitchto the 20 V position.
10. Connectthe Voltage Leakagetest leads;the RED leadis
connectedto the battery side of the coil andthe BLACK lead is
connectedto agood ground.
11. Removethe high tensionwirefrom the coil and leave the
wiredisconnected.
12. Insert the scopepatternpickup into the coil tower and
attachthe groundclip to a good ground.
13. Set the scopeground polarityswitch to the POSITIVE +
position.
14. Turn the scopedisplay selectorto the SCOPE CHECK position
andadjust the horizontal and verticalknobs until the traceappearson
theZERO 0 line allow about 30secondsfor warm-up before
adjustment.
CRANKING VOLTAGE
1. With the testerconnected,turnthe ignition switch ON. Make
surethat the transmission is in neutraland that the parking brake
is set.
2. Crank the engine, observethespeed and note the reading on
thevoltmeter.
If the meter reads less than thespecified voltage, check for the
following: weak battery, defectivecables, connections, switch,
starter,by-passcircuit, or ignition circuit tocoil.
If the speed is uneven or slow,the engine or starting circuit
isdefective.
BREAKER POINTS
1. With the motor tester connected,turn the scopedisplay
selector to the INDIVIDUAL CYLINDER position.
2. Removethe jumper lead fromthe distributor to ground.
3. insertthecoil high tensionwireinto the
scopepatternpickup.
4. Operate the engine at 1200rpm.
5. Observe the point open andpoint close signals Fig. 24. If
anunusual point close signal is obtainedan unusualpoint
closesignalis one that does not have a shortstraight downward line
followed bya series of closely grouped rapidlydiminishing
oscillations, check forpoor point contact, misalignedpoints, or
weakpoint spring tension.
If an unusualpoint open signal is
188
obtained an unusual point opensignal is one that does not form
afiring line that is straight up anddown, check for dirty or
burnedpoints, or high series resistance.
COIL
Polarity
1. Removethe jumper lead fromthe distributor to ground, if it
isstill connected.
2. Insertthe coil high tensionleadinto the
scopepatternpickup.
3. Adjust the engine speedto 1200rpm.
4. Turn the scopedisplay selectorto the ALL CYLINDERS
position,and adjust the patternlength controluntil all
cylindersappearbetweenthevertical lines on both sides of
thescreen.
5. Rotate the pattern shift control counterclockwiseuntil the
lastpatternon the screenappearscomplete.
6. Observethe patterns,noting ifthey are upright or inverted
Fig.24.
If they are inverted,checkfor thescopeground polarity switch in
theMINUS - position, batterypolarity reversed, coil improperly
connected,or incorrectcoil.
Primary and Secondary Tests.To check the coil for shorted oropen
windings and for primary orsecondary resistance,calibrate
theCondenser-CoilUnit asfollows:
1. Turn the AC switch to ON.2. Set the Condenser-Coil Unit
selectorswitch at the OHMS position.
3. Set the Condenser-Coilohmsswitch to the desired range.
4. Connectthe test leadstogether.5. Adjust the
Condenser-Coilcali
brator until the meter pointer readsZERO on the ohms scale.
6. Disconnectthe test leads.7. Disconnect all leads from the
coil.INTS
POINTS OPEN
CLOSE
SECTIONINTERMEDIATE
SECTION DWELL SECTION
SHORTED OR OPEN WINDINGS.
1. Calibrate the Condenser-CoilUnit the ohm switch should be
inthe OHMS position.
2. Connect the test lead, one toeach coil primary terminal.
Observethe polarity.
3. Insert the coil pickup into thesecondarytower of thecoil
andcon-
81 727-A fleet thegroundleadof the pickup toa good ground.
4. Turn the Condenser-CoilUnitFIG. 24-Typical Scope Pattern
-
PART 9-1-GENERAL IGNITION SYSTEM SERVICE 9-13
selectorswitch to the COiL TESTposition and observethe wave
pattern visible on the coil test scope.
Referto Fig. 25 for checkingthedata obtained.
PRIMARY RESISTANCE
1. Calibrate the Condenser-CoilUnit set the ohm switch to
theOHMS position.
2. Connect the test leads, one toeachprimary terminal of the
coil.
3. Observethe meter reading andcompareit with
specifications.
SECONDARY RESISTANCE
1. With the ohm switch set at theOHMS x 1000 position,
calibratetheCondenser-CoilUnit.
2. Install the coil pickup test leadin the tower of the
coil.
3. Connect the ohmmeter testleads,one to either primary
terminaland the other to the open pigtailend of the coil pickup
test lead.
4. Observethe meterreadingandcompareit with specifications.
If the meter reading exceeds20,000ohms, the secondarywindingis
open.
CONDENSER
For the condensertests, calibratethe Condenser-CoilUnit as
follows:
1. Set the selector switch to theCONDENSERposition.
2. Connectthe test leadstogether.3. After allowing
approximately
one minute for the tester to warmup, adjust the calibrator until
themeter pointer reads on the set lineat the right end of the meter
scale.Do not change this setting duringthe tests.
Resistance
1. Connectthe test leads, one tothe primary terminal of the
distributor andthe other to a groundon thedistributor body.
2. With the condensertest switchin the SERIES RESISTANCE
posi
tion, the meter should read in theblack bar at the right end of
thescale.
3. Move the condenserpigtail. Ifa deflection of the meter is
noted,the pigtail is making poor contactandthecondensershouldbe
replaced.
If the readingis outside the blackbar, move the groundedleadto
thebody of the condenser.If the reading improves, the condenseris
notproperly groundedto the distributorhousing.
Capacity
1. Turn the condensertest switchto the CAPACITY position.
2. Read thered scaleof the meter0.5 for the
microfaradcapacityofthe condenserbeingtested.
3. Refer to the specifications forthe recommendedcondenser
capacity.
if the readings are not withinspecificationsreplace the
condenser.
Leakage
1. Turn the condensertest switchto the LEAKAGE position.
2. The meter should now read inthe black bar at the left end of
thescale if the condenserleakageis satisfactory.
If the meter pointer readsoutsidethe black bar, the
condenserinsulation is leaking and the condensershould be
replaced.
NOTE: If the condenserdoes notmeet specificationswhile
mountedinthe distributor,removethe condenserandretestit. The
sameprocedureisfollowed as above. If the condensertests badin the
distributor, but testsgood when removed,thereis a shortor ground in
the distributor primarycircuit. Inspectthe insulation of
thedistributor primary terminal and theinternal circuit of the
distributor.
FIRING VOLTAGE
I. Remove the jumper from thedistributor to ground.
2. Insert the coil high tensionleadinto the scopepickup.
3. Adjust the engine speed to1200 rpm.
4. Turn the scopedisplay selectorto the ALL CYLINDERS
position,and adjust the patternlength controluntil all of the
cylinders appearbetweenthe vertical lines on the screen.
5. Rotate the patternshift controlcounterclockwiseuntil the last
pattern on the screenappearscomplete.
6. Observethe height of each firing line, on the scope,
andcomparefor uniformity and height Fig. 24.
If the firing voltagesare uniform,but high, checkfor worn
sparkplugs,late ignition timing, lean fuel mixture, too large a
rotor gap, or abreakin the coil wire.
If the firing voltages are uneven,check for worn spark plugs,
unevencompression, breaks in spark plugwires, or a cocked or worn
distributor cap.
AVAILABLE VOLTAGE
1. Makethe sameconnectionsandadjustmentsas for the firing
voltagetest above.
2. Disconnecta spark plug wirewith a pair of
insulatedpliers.
3. Hold the wire away from agroundandnoticetheupwardextentof the
pattern on the scope.
If the availablevoltage is less than20 KV, checkfor
excessiveresistancein the primary circuit, low primaryinput
voltage, defective coil, dwellless than specified, or
defectivesecondaryinsulation.
SECONDARY INSULATION
1. Continue with the same connections and adjustmentsas in
thelast two tests.
2. Observethe downward extentof the patternof the sparkplug
withthe wire removed.
3. Connectthe sparkplug wire.4. Perform this test on all of
the
cylinders trigger cylinder may betestedin the SCOPE CHECK
position.
if the lower extent is not at leasthalf the size of the upper
extent,check for insulation leakage in thecoil, coil tower, rotor,
coil wire, distributor cap, or spark plug wire.
SECONDARY RESISTANCE
1. The connections and adjustments for this test are the same
asfor the last three tests, except forthe scope display selector
switchwhich is now placed in the ALLCYLINDERS position.
189
FIG. 25-Coil Test Patterns
-
9-14 GROUP 9-IGNITION SYSTEM
2. Observeandcomparethe sparkline Fig. 24 of the patterns
forlength,height,angleandoscillations.
If all cylinders areaffected, checkfor high resistancein the
coil tower,coil wire, rotor, or distributor captower; also check
for an accumulation of depositson the spark plugs,or poor contact
between the rotoranddistributor cap.
If one or more cylinders areaffected,checkfor high
resistanceinthe distributor cap tower, sparkplugwires, or
sparkplugs.
SPARK PLUGS
To test the sparkplugs on the car,connectthe motor testerin the
samemanneras for the firing voltagetest.
1. Turn the displayselectorswitchto the ALL CYLINDERS
position;rotatethe patternshift control in theFULL CLOCKWISE
position.
2. Momentarilyacceleratethe engine to about 2000 rpm and
returnto 1200 rpm.
3. Observethe rise of the firinglines during the
momentaryengineacceleration.
If one or more of the firing linesis higher than the others,
check forwide plug gap, open spark plug resistor wire, or badly
deterioratedelectrodes.
If one or more of the firing linesis lower than the others,
check forspark plug fouling, fiashover, orcrackedinsulators.
DISTRIBUTOR DIAPHRAGMLEAKAGE AND FREENESSOF OPERATION
These tests can be made with thedistributor installed on the
engine.The testsaresufficient for an enginetune-up.However, if
there are indicationsthat the sparkadvanceis notfunctioning
properly, remove thedistributor from the engine andcheck it on a
distributor test setfollowing the instructions under"Distributor
SparkAdvance."
Checkthe vacuum advancemechanism for freenessof operation
bymanually rotating the breakerplatein the directionof rotation. Do
notrotate the plate by pushing on thecondenser or the breaker
points.Use a hook or other suitable instrument to rotate the plate.
Thebreaker plate should turn withoutbinding and return to ¶ts
originalposition when released.If thebreaker plate binds, remove
the plate.Clean, inspect andlubricate it as describedfor the
particular distributor.
To checkthe diaphragmfor leak-age:
1. Remove the vacuum line fromthe distributor. Adjust the
vacuumpressureof a distributor testerto itsmaximum position. Hold
your handover the endof the tester’svacuumhoseandnote the
maximumreadingobtained.Do not exceed25 inchesHg.
2. If the maximum reading is 25inchesHg or
less,connectthetester’svacuumline to the vacuumfitting onthe
diaphragm without changingany of the adjustments.The maximum gauge
readingshould not beless than it was in step 1. If it isless, the
diaphragm is leaking andshould be replaced.
DISTRIBUTOR BREAKER PLATEWEAR
A worn breaker plate will causethe breaker point gap and
contactdwell to changeas enginespeedandload conditions are varied.
Mountthe distributor in a distributor testerfollowing the
instructions in this section of the manual.
Adjust the test to 0 advance,0 inchesvacuum,and1000 rpm.Adjust
the dwell angle to 26°. Applyvacuum to the distributor
diaphragmandincreaseit very slowly while observing the indicated
dwell angle.The maximumdwell angle variationshould not exceed 6°
when goingfrom zero to maximum vacuum atconstant rpm. If the dwell
anglevariation exceedsthis limit, there isexcessivewear at the
stationarysub-plate pin or the diaphragm rod isbent or
distorted.
DISTRIBUTOR SHAFT END PLAY1. Removethedistributor from the
190
engine.2. Place the distributor in the
holding tool and clamp it in a vise.3. Push the distributor
shaft up
ward as far as it will go, then checkthe end play with a feeler
gaugeplaced between the collar and thedistributor base.The endplay
shouldbe within the specified limits.
If the shaft end play is not tospecifications,check the location
ofthe distributor shaft collar.
DISTRIBUTOR TESTS-ROTUNDA RE-1416 TESTER
MOUNTING DISTRIBUTOR
1. Clamp the distributor securelyin the distributor supportarm
clampso that it will not turn in its mounting.
2. Loosenthe hand-operatedlocking screwonthesideof
thedistributorsupport arm and adjust the supportarm column up or
down by turningthecrankon theknob at thetop of thecolumn until the
distributor shaft oradapter shaft can be securelyfastenedin the
driving chuck. Useadaptershafts provided when driving distributors
having short shafts.
3. Securelytightenthe drive chuckto the distributor drive shaft
bymeansof the chuck key, attachedbya chain to the Syncrograph
4. Rotate the drive chuckby handto make sure the distributor
shaftturns freely and then tighten thelocking screwon the
distributor support arm.
FIG. 26-TestingTransistor Ignition Distributor
5. Connect the Syncrographtestlead to the primary or
distributor-transistorleadwire of the distributor.Since the
transistor ignition distrib
81990-A utor does not have a condenser,itwill be necessaryto
install one inthe circuit of the testerFig 26.
BREAKER POINT RESISTANCE
1. Turn thetest selectorto POINTRES. position.
2. Revolvethechuck by handuntilthe distributor breaker points
areclosed.
3. The meter pointer on the camangle meter should read in the
OKzone at the left side of the meterscale If the meter pointer does
notfall in the OK zone, thereis excessiveresistancecausedby a
faulty contactacrossthe distributor points, a faultyprimary lead or
a poorly groundedbaseplate.A faulty contactacrossthedistributor
points indicatesimproperspring tension or burned or
pittedpoints
-
PART 9-1-GENERAL IGNITION SYSTEM SERVICE 9-15
INSULATION AND LEAKAGE
1. Turn the test selector to thecam angle position and revolve
thechuck by hand until the distributorbreakercontactsare open
2. The cam angle meter shouldshow a zero reading. If a zero
reading is not obtained,a short circuit toground exists
A short could be causedby poorprimary or
distributor-transistorleadwire insulation, a shortedcondenseror a
short betweenthe breakerarmandbreakerplate
MECHANICAL OPERATION
1. Turn the test selector to theSYNCHRO. position and check
tomakesure the drive chuck is securelytightenedon the distributor
shaft.
2. Turn the motor control switchto the left to correspondwith
thedirection of rotation, as listed in therotation column of the
distributorspecifications.
If it is necessaryto reverse therotation of the drive motor,
turnthe motor control switch to theOFF position and allow the
chuckto cometo a complete stop beforereversing the switch.
3. Adjust the rpm control to varythe distributor speed between
400and 4000 enginerpm or at the maximum speedof the engineon
whichthe distributor is used. Erratic orthin faint flashesof light
precedingthe regular flashes as the speed ofrotation is
increasedcan be due toweak breaker arm spring tension orbinding of
the breaker arm on thepivot pin
. Operate the distributor at approximately 2500 enginerpm.
5. Move the protractor scalewith
the adjustmentcontrol so that thezero degree mark on the scale
isoppositeoneof the neonflashes.Thebalanceof all the flashesshould
comewithin 1°, plus or minus, evenlyaroundthe protractorscale.A
largervariation than 1° or erratic or wandering flashes may be
causedby aworn cam or distributor shaft or abent distributor
shaft.
DWELL ANGLE
1. Turn the cylinder selector tothe figure correspondingto
thenumber of lobes on the cam of the distributor being tested.
2. Turn the test selectorswitch tothe cam angle position and
operatethe distributorat approximately1000enginerpm.
3. Adjust the distributor breakerpoint gap to the dwell angle
shownin the specifications.
DISTRIBUTOR SPARKADVANCE
The spark advanceis checkedtodetermineif the ignition timing
advances in proper relation to enginespeedand load.
1. Check the contact dwell. If thecontact dwell or the breaker
pointgap is not within specifications,adjust the breakerpoints.
2. Check the breaker arm springtension andadjust it if
necessary.
FIG. 28-VacuumAdvance Adjustment
The dual advancedistributor hastwo independently operated
sparkadvancesystems.Eachsystem is adjusted separately. Adjust the
centrifugal advance before adjustingthe vacuum advance.
Centrifugal Advance
1. Do not connectthe test setvacuum line to the diaphragm.Set
thetest set to 0° advanceand the initialrpm settinglisted in
thespecifications.
2. Operate the distributor in thedirection of rotation
counterciock
191
wise andslowly increasethe rpm tothe setting specifiedfor the
first advancereadinglisted in the specifications.
If the correctadvanceis not indicatedat this rpm, stopthe
distributorand bend one spring adjustmentbracket to change its
tension Fig.27. Bend the adjustment bracketaway from thedistributor
shaft todecreaseadvance increase springtension and toward the shaft
toincrease advancedecreasespringtension. After the adjustment
ismade,identify the bracket.
3. After an adjustmenthas beenmadeto onespring, checkthe minimum
advancepoint again.
4. Operate the distributor at thespecifiedrpm to give an
advancejustbelowthe maximum. If this advanceis not to
specifications,stop thedistributor and bend the other
springbracketto give the correctadvance.
5. Check the advanceat all rpmsettings listed in the
specifications.Operatethe distributor both up anddown the rpm
range.
Vacuum Advance
1. Connect the test set vacuumline to the fitting on the
diaphragmand turn the vacuumsupply switchon.
2. Set the test set to 0° advance,0 vacuum,and at 1000 rpm.
3. Check the advanceat the firstvacuum setting given in the
specifications. -
SPACING WASHERS
4. If the advance is incorrect,change the calibration washers
between the vacuum chamber springand nut Fig. 28. After
installingor removing the washers, positionthe gasket in place and
tighten thenut. The addition of a washerwilldecreaseadvanceand the
removal
B20 11-A of a washer will increase advance.5. After one vacuum
setting has
beenadjusted, the othersshould bechecked.Do not changethe
originalrpm setting when going to a different vacuum setting. If
the othersettings are not within limits, it
indicatesincorrectspring tension, leakage in the vacuum
chamberand/orline, or the wrongfiber stop hasbeeninstalled in the
vacuum chamberofthe diaphragmhousing.
DISTRIBUTOR TESTS-ROTUNDA RE-236 TESTER
MOUNTING DISTRIBUTOR
1. Adjust the distributor supportarm in relation to the
distributorshaft length.
FIG. 2l-CentrifugalAdvance Adjustment
-
GROUP 9-IGNITION SYSTEM
2. Set the distributor in the support arm and enter the lower
endof the distributor shaft in the Syncrographchuck.
3. Tighten the chuck on the distributor shaft, using the wrench
locatednearthe supportarm column.
4. Align the distributor shaft byshifting the supportarm
anddistributor, then tighten the clamp screw.
5. Clamp the distributor securelyin thedistributor supportarm
clampso that it will not turn in its mounting.
MECHANICAL OPERATION
1. Turn the OFF, SET, CAM,SYNC. switch to SET.
2. Adjust the SET TACH controlso the tachometerpointer is on
theSET line.
3. Turn the OFF, SET, CAM,SYNC. switch to SYNC. position.
4. Turn the MOTOR switch to theLEFT position.
5. Adjust the speedcontrol to varythe distributor speed
between400and4000 enginerpm, or at themaximum speedof the engineon
whichthe distributor is used. Erratic orthin faint flashesof light
precedingthe regular flashes as the speed ofrotation is
increasedcan be due toweakbreakerarm spring tensionorbinding of the
breaker arm on thepivot pin.
6. Operate the distributor at approximately 2500 engine rpm
andmovethe protractorscaleso that thezero degreemark on the scaleis
opposite one of the neon flashes. Thebalance of all the flashes
shouldcomewithin 1°, pius or minus, evenly around the protractor
scale. Avariationlargerthan 1° or erraticorwanderingflashesmay be
causedbya worn cam or distributor shaft ora bent distributor
shaft.
DWELL ANGLE
1. Turn the OFF, SET, CAM,SYNC. switch to the CAM
position.Operatethe distributorat about1000rpth.
2. Adjust the breaker point gapuntil the cam angle is to
specifications.
DISTRIBUTOR SPARKADVANCE
The spark advanceis checkedtodetermineif the ignition timing
advances in proper relation to enginespeedand load.
1. Check the contactdwell. If thecontact dwell or the breaker
point
gap is not within specifications,adjust the breakerpoints.
2. Check the breaker arm springtension andadjust it, if
necessary.
The dual advancedistributor hastwo independently operated
sparkadvancesystems.Eachsystemis adjusted separately.Adjust the
centrifugal advance before adjustingthe vacuum advance.
Centrifugal Advance
1. Do not connect the test setvacuum line to the
diaphragm.Setthe test set to 00 advanceand theinitial rpm setting
listed in thespecifications.
2. Operate the distributor in thedirection of rotation
counterclockwise and slowly increasethe rpmto the setting specified
for the firstadvancereading listed in the specifications.
If the correctadvanceis not indicated at this rpm, stop the
distributor and bend one spring adjustment bracket to change its
tensionFig. 27. Bend the adjustmentbracket away from the
distributorshaft to decreaseadvanceincreasespring tension and
towardthe shaftto increaseadvancedecreasespringtension. After the
adjustment ismade, identify the bracket.
3. After an adjustmenthas beenmadeto onespring, check theminimum
advancepoint again.
4. Operate the distributor at thespecifiedrpm to give an
advancejustbelow the maximum. If this advanceis not to
specifications,stop the distributor and bend the other
springbracket to give the correctadvance.
5. Check the advanceat all rpmsettings listed in the
specifications.Operatethe distributor both up anddown the rpm
range.
Vacuum Advance
1. Connect the test set vacuumline to the fitting on the
diaphragm.
2. Set the test set to 0° advance,0 vacuum,andat 1000 rpm.
3. Check the advanceat the firstvacuum setting given in the
specifications.
4. If the advance is incorrect,change the calibration
washersbetween the vacuum chamber springand nut Fig. 28. After
installingor removingthewashers,positionthegasket and tighten the
nut. Theaddition of a washer will decreaseadvance and the removal
of awasher will increase advance.
5. After one vacuum setting has
beenadjusted, the othersshould bechecked.Do not change the
original rpm setting when going to adifferent vacuum setting. If
theother settings are not within limits,there is .incorrect spring
tension,leakagein the vacuumchamberand/or line, or the wrong fiber
stop hasbeeninstalled in the vacuum chamber of the
diaphragmhousing.
DISTRIBUTOR TESTS-SUN DT-600 TESTER
MOUNTING
1. Using the elevationcrank, raisethe clamp arms high enoughto
permit the shaft of the distributor toclear the drive chuck.
2. Position the distributor in theclamp with the vacuum
diaphragmpointing toward the right. Tightenthe clamp
armssecurelyaroundthedistributor body. Install the properadapterto
thevacuum diaphragm.
3. Lower the distributor with theelevation crank until the gear
or¾ inch of the tip of the distributorshaft entersthe drive chuck,
or untilthe shaft engagesthe adapter if anadapteris being used. Do
not bottom the distributor shaft in thechuck.
4. Tighten the chuck. Do not tryto raise or lower the
distributorafter thechuckhasbeentightened.
CONDENSER TESTING
Condensersshould be testedforseriesresistance,capacity and
leakage. The preparationprocedure isas follows:
1. Trip the motor switch to theproper position for the rotation
ofthe distributor being tested.
2. Turn the condensertest selector switch to the SERIES
RESISTANCE position andconnectthe con-densertest leads
together.
3. Turn the condenser calibratecontrol clockwise from the OFF
position.
4. Allow thetesterto warm up forapproximately30 secondsand
thenadjust the calibratecontrol until thecondensermeter readson the
SETLINE.
5. Rotate the distributor sha’t untilthe cam holds the breaker
pointsopen.
6. Separatethe test leads andconnect one to the distributor
primaryleadand the other to the distributorbody.
SeriesResistance.Turn the condenser test selector switch to
the
9-16 192
-
PART 9-1-GENERAL IGNITION SYSTEM SERVICE 9-17
SERIES RESISTANCE position.The condenser meter should read inthe
black bar on the right endof thescale.
Capacity. Turn the condensertestselectorswitch to the
CAPACITYposition. The condensermeter willnow readthecapacityin
microfarads.Comparethis reading with specifications.
Leakage.Turn the condensertestselector switch to the
LEAKAGEposition. The condensermetershouldread in the black bar at
the left ofthe scale.
Turn the test selectorswitch tothe SERIES RESISTANCE positionand
turn OFF the condensercalibrator before disconnectingthe
testleads.
DISTRIBUTOR RESISTANCE
1. With the motor switch in theproper position for the rotation
ofthe distributor being testedand thespeed set at ZERO rpm, clip
thetester’s distributor and ground leadtogether.
2. Set the tachometerdwell selector switch to the CALIBRATE
position andadjustthe dwell regulatoruntil the dwell meter reads on
theSET LINE.
3. Separate the leads and connectthe tester’s distributor lead
to thedistributor primary or distributor-transistor lead. Since the
transistorignition distributor does not havea condenser, it will be
necessaryto incorporate one in the test circuit Fig. 26. The tester
groundleadshould now be connectedto thedistributor body.
4. Rotate the chuck by handuntilthe points are closed. The
dwellmeter should read in the black barat the right end of the
scale.
If it does not read in the blackbar,movethe
tester’sdistributorwirestep by step through the circuit toward the
ground. When there is ameasurabledifference between twopoints,
checkthat areafor the causeof the resistance.
CAM LOBE ACCURACY
1. Connectthe test leadsfollowingthe directions in the
distributor resistancetest.
2. Turn theswitch to the 8
3. Adjust the1000 rpm.
4. Rotate the degreering of thetester until the ZERO on the
ringlines up with one of the flashes.
5. Observethe positions of the remaining flashes.If
theflashesarenotevenly spacedwithin ±10, checkfor a worn cam, worn
distributorshaft or a bent distributorshaft.
DWELL ANGLE
This test hasthe sameconnectionsas the precedingtest,
thereforetheycan be doneat the sametime.
Adjust the speedto 200 rpm andnotice the dwell reading. If it is
notwithin specifications, adjust thepoints until the properdwell is
obtained. Now increasethe speedandcheckthe dwell reading. If the
reading changesmore than two degrees,check for a worn distributor
shaftor worn bushings.
DISTRIBUTOR SPARKADVANCE
The spark advanceis checkedtodetermineif the ignition timing
advances in proper relation to enginespeedand load.
1. Check the contactdwell. If thecontact dwell or the breaker
pointgap is not within specifications,adjust the breaker
points.
2. Check the breaker arm springtension and adjust it if
necessary.
The dual advancedistributor hastwo independently operated
sparkadvancesystems.Eachsystemis adjusted separately.Adjust the
centrifugal advancebefore adjustingthevacuum advance.
Centrifugal Advance
1. Do not connectthe test set vacuum line to the diaphragm.Set
thetest set to 0° advanceandthe initialrpm settinglisted in
thespecifications.
2. Operate the distributor in thedirection of rotation
counterciock
wise andslowly increasethe rpm tothe setting specifiedfor the
first advance reading listed in the specifications.
If the correctadvanceis not indicatedat this rpm,
stopthedistributorand bend one spring adjustmentbracket to change
its tension Fig.27. Bend the adjustment bracketaway from the
distributor shaft todecreaseadvance increase springtension and
toward the shaft toincrease advance decreasespringtension. After
the adjustment ismade,identify the bracket.
3. After an adjustmenthas beenmadeto onespring, checkthe minimum
advancepoint again.
4. Operate the distributor at thespecifiedrpm to give an
advancejustbelow the maximum. If this advanceis not to
specifications,stop thedistributor and bend the other springbracket
to give the correctadvance.
5. Check the advanceat all rpmsettings listed in the
specifications.Operatethe distributor both up anddown therpm
range.
Vacuum Advance
1. Connect the test set vacuumline to the fitting on the
diaphragm.
2. Set the test set to 00 advance,0 vacuum,andat 1000 rpm.
3. Check the advanceat the firstvacuum setting given in the
specifications.
4. If the advance is incorrect,change the calibration
washersbetween the vacuum chamberspringandnut Fig. 28. After
installing orremoving the washers,position thegasket and tighten
the nut. The addition of a washer will decreasethe advance and the
removal of awasher will increasethe advance.
5. After one vacuum setting hasbeenadjusted, the othersshould
bechecked. Do not change the original rpm setting when going to
adifferent vacuum setting. If theother settings are not within
limits,it indicates incorrect spring tension,leakagein
thevacuumchamberand/or line, or the wrong fiber stop
hasbeeninstalled in the vacuum chamber of the diaphragmhousing.
B COMMON ADJUSTMENTS AND REPAIRSBREAKER POINTS
ADJUSTMENT
NewBreaker Points. Newbreaker points can be adjusted with a
feeler gauge,scopeor a dwell meter.To adjustthe breakerpoints
with
a feeler gauge:1. Check and adjustbreakerpoint
alignment. Rotate the distributor
camuntil the rubbingblock rests onthe peak of a camlobe.
If the car is equipped with atransistor ignition and the starter
is going to be tapped to place
193
tachometer dwellposition.distributor speedto
-
9-18 GROUP 9-IGNITION SYSTEM 194
the breaker point assembly on thepeak of the cam, proceed as
follows: connect a juniper betweenthe "S" terminal of the
solenoidand the battery with the ignitionswitch off and the coil
lead brownwire disconnectedfrom the solenoid.
2. Insert the correct blade of
acleanfeelergaugebetweenthebreaker points Fig. 29. The gap shouldbe
set to the largeropeningbecausethe rubbing block will wear
downslightly while seatingto the cam.
3. Apply a light film of distributorcam lubricantto the camwhen
newpoints are installed. Do not use engine oil to lubricate the
distributorcam.
4. Set the ignition timing.If a scopeor a dwell meter is
used
to adjust new points, be sure thepoints arein properalignment.
Also,
CONTACTAREA
- CENTERED
CORRECTALIGNMENT
CONTACT- AREA NOTIiCENTERED
MISALIGNMENTOF CENTERS
CONTACT-
- :- AREA NOTCENTERED
MISALIGNMENTOF POINT FACES B1019-A
FIG. 30-Breaker Point
FIG. 3l-AligningBreaker Points
set the contactdwell to the low setting. New points must be set
to thelow dwell as the rubbing block willwear down slightly while
seating tothe cam.
Used Breaker Points. If the gapof used breaker points is
beingchecked,use a scopeor dwell meterto test the contact dwell. It
is notadvisableto use a feeler gauge toadjust or to check the gap
of usedbreakerpoints becausetheroughnessof the points makesan
accurategapreading or setting impossible.Cleanthe breakerpoints.
Check the contact dwell following the instructionsunder "Ignition
SystemTests". Thecontactdwell should be to specifications. Check
and adjust the ignitiontiming.
FIG. 33-AdjustingSpring Tension
ALIGNMENT
The vented-type breaker pointsmustbe
accuratelyalignedandstrikesquarely in order to realizethe
fulladvantagesprovided by this design,andassurenormalbreakerpoint
life.Any misalignment of the breakerpoint surfaceswill
causeprematurewear, overheatingandpitting.
1. Turn the camso that thebreaker points are closed and check
thealignmentof the points Fig. 30.
If the carhasa transistor ignition system, refer to the
adjustment of new breaker points forthe proper starter tapping
procedure.
2. Align the breaker points tomake full face contact by
bendingthe stationarybreakerpoint bracketFig. 31. Do not
bendthebreakerarm.
3. After the breaker points havebeen properly aligned, adjust
thebreakerpoint gap or dwell.
FIG. 29-Adjusting NewBreaker Point Gap
STATIONARY BRACKET B2012-A
LESS TENSION 82013-A
FIG. 32-CheckingBreaker Point Spring TensionAlignment FIG.
34-Timing Marks
-
PART 9-1-GENERAL IGNITION SYSTEM SERVICE 9-19
ADJUSTING SPRING TENSION
Correct breakerpoint spring tension is essential to proper
engineoperationand normal breakerpointlife. If the spring tension
is toogreat, rapid wear of the breakerarmrubbingblockwill result,
causingthebreakerpoint gap to close up andretardthe sparktiming. If
thespringtension is too weak, the breakerarmwill flutter at high
engine rpm resulting in an enginemiss.
To checkthe spring tension, placethe hookedendof the spring
tensiongauge over the movable breakerpoint. Pull the gauge at a
rightangle 90° to the movable armuntil the breakerpoints just start
toopen Fig. 32. If the tension is notwithin
specifications,adjustthe springtension.
To adjust the spring tension Fig.33:
1. Disconnectthe primary or distributor-transistorleadwire,
andthecondenserleadif so equipped,at thebreakerpoint
assemblyprimary terminal.
2. Loosen the nut holding thespring in position. Move
thespringtoward the breaker arm pivot todecreasetension and in the
opposite direction to increasetension.
3. Tightenthelock nut, thencheckspring tension.Repeatthe
adjustmentuntil the specified spring tension isobtained.
4. Install the primary or distributor-transistorleadwire,
andthecondenser lead if so equipped, withthe lock washer andtighten
the nutsecurely.
IGNITION TIMING
TIMING MARK LOCATIONS
The crankshaftdamperFig. 34has 15 timing marks ranging fromtop
deadcenter TDC to 30° before top deadcenterBTDC. Referto
specificationsfor the correctignition timing.
ADJUSTMENT
The procedurefor adjusting theignition timing is covered
under"Ignition SystemTests".
SPARK PLUG WIREREPLACEMENT
When removingthewiresfrom thespark plugs, grasp the moulded
caponly. Do not pull on thewire becausethe wire connectioninside
the cap
maybecomeseparatedor the weathersealmaybe damaged.
A typical ignition wiring installation is shown in Fig. 35.
REMOVAL
1. Disconnect the wires from thesparkplugs anddistributor
cap.
2. Pull thewires from thebracketson the valve rocker arm covers
andremovethe wires.
3. Remove the coil high tensionlead.
INSTALLATION
1. Insert eachwire in the propersocketof the distributor cap. Be
surethe wiresareforcedall the way downinto their sockets.The No. 1
socketis identified on the cap. Install thewires in a
counterclockwisedirection
FIG. 36-GappingSpark Plugs
in the firing order 1-5-4-2-6-3-7-8starting at the No. 1 socket.
Cylindersarenumberedfrom front to rear;right bank 1-2-3-4, left
bank 5-6-7-8.
2. Removethe bracketsfrom theold spark plug wire set and
installthem on the new set in the samerelative position. Install
the wires inthe bracketson the valve rockerarmcovers Fig. 35.
Connectthe wiresto the propersparkplugs. Install thecoil high
tension lead. Be sure theNo. 7 spark plug wire is positionedin
thebracket as shown in Fig. 35.
SPARK PLUGS
REMOVAL
1. Remove the wire from eachsparkplug by graspingthe mouldedcap
of thewire only. Do not pull onthe wire becausethe wire connection
inside the cap may becomeseparatedor the weather sealmaybe
damaged.
2. Clean the area around eachsparkplug port with
compressedair,then removethe sparkplugs.
ADJUSTMENT
Setthe sparkplug gapby bendingthe groundelectrodeFig. 36.
INSTALLATION
1. Install the spark plugs andtorqueeach plug to
15-20ft-lbs.
When a new sparkplug is installedin a new replacementcylinder
head,torquethe plug to 20-30ft-lbs.
2. Connect the spark plug wires.Pushall weathersealsinto
position.
RESISTANCE WIREREPLACEMENT
The primary resistance wire ischecked for
excessiveresistanceasoutlined under "Resistance WireTest".
195
FIG. 35-Ignition Wiring
-
GROUP 9-IGNITION SYSTEM
FIG. 3l-Cleaning PlugElectrode
To replacethe resistancewire:1. Remove the instrument panel
lower covers.2. Disconnect the resistancewire
pink or black from the multiplemolded connectorat the
PowerBox.This connectoris the secondfromthe top of the Power Box,
and thepink or black resistancewire plugsinto the upper right
corner of theconnector.
3. Cut off the old resistancewireat the point whereit
entersthemain14401 wiring loom.
4. Connectthe replacementpinkor black wire to the multiple
connector at thePowerBox.
5. Route the replacementwire asstraight as possibleunderthe
instrument panel,to theconnectorneartheignition switch.
6. Disconnect the old wire at thequickdisconnectredwire with
greenconnector near the ignition
switchandconnectthereplacementwire.
7. Cut off the old resistancewirewhereit entersthemain wiring
loom.
8. Tape the replacementwire tothemain wiring loom.
IDENTIFICATION I CAUSED BYWet, sludgy deposits. Excessive oil
entering combustion
chamber through worn rings andpistons,
excessiveclearancebetweenvalve guides and stems,or worn
orloosebearings.
Dry, black,posits.
fluffy de- Incompletecombustioncausedby toorich a fuel-air
mixture or by a defective coil, breakerpoints or ignitioncable.
White, burned, or Inefficient engine cooling, or engineblistered
insulator overheatingcausedby improperigninoseanderodedelec- tion
timing, wrong typeof fuel, loosetrodes. spark plugs, or too hot a
plug, low
fuel pumppressure.
Rusty brown to gray-ish-tanpowderdeposit
Regular or unleadedgasoline.
andminor electrodeerosion.
White, powdery de- Highly leadedgasolines.posits.
Hard, bakedon black Too cold a plug. Weak ignition, decarbon.
fective fuel pump, dirty air cleaner,
too rich a fuel mixture.
Hardandscratchy Formedwhenfinesandparticlescombine with
anti-knock compoundsinthe fuel. Most common industryareas.The plugs
cannot be cleaned.
Deposits, accumulatedafter a longperiodof misfiring,
suddenlyloosenedwhen normal combustion
chamberdepositsarerestoredafter new plugsare installed. During a
high speedrun these deposits are thrown intothe plug. 81005-E
9-20 196
I- 781390-B
FIG. 38-Spark Plug Inspection
-
PART 9-1 -GENERAL IGNITION SYSTEM SERVICE 9-21
0 CLEANING AND INSPECTIONSPARK PLUGS
Clean the plugs on a sand blastcleaner,following
themanufacturer’sinstructions. Do not prolong the useof the
abrasiveblast as it will erodethe insulator. Remove carbon andother
depositsfrom the threadswitha stiff wire brush. Any deposits
willretardtheheatflow from the plug tothe cylinder
headcausingsparkplugoverheatingand pre-ignition.
Clean the electrodesurfaceswitha small file Fig. 37.
Dresstheelectrodesto secureflat parallel surfacesonboth
thecenterandsideelectrode.
After cleaning,examinethe plugcarefully for crackedor broken
insulators,badly pitted electrodes,andother signs of failure.
Replaceas required.
Examine the firing ends of thespark plugs, noting the type of
deposits and the degree of electrodeerosion.Referto Fig. 38 for
thevarious typesof spark plug fouling andtheir causes.
DISTRIBUTORS
Soak all parts of the distributorassembly except the
condenser,breaker point assembly, lubricatingwick,
vacuumdiaphragm,distributorbase oil seal, and electrical wiringin a
mild cleaningsolvent or mineralspirits. Do not use a harsh
cleaningsolution. Wipe all parts that can notbe immersedin a
solventwith a cleandry cloth.
After foreign deposits have beenloosenedby soaking, scrub the
partswith a soft bristle brush.Do not usea wire brush,file, or
other abrasiveobject. Dry the parts with compressedair.
Examine the bushing surface ofthe distributor shaft andthe
bushingfor wear. The dual advancedistributor hasonebushing.The
minimumallowableshaft diameterat thebushing is 0.4675inch andthe
maximumallowableinsidediameterof thebushing is 0.4690 inch. Replace
wornparts.
Inspectthe distributor cam lobesfor scoringandsignsof wear. If
anylobe is scoredor worn, replacethecamassembly.
Inspectthebreakerplate assemblyfor signs of distortion. In
addition,inspect the stationary sub-plateforworn nylon
contactbuttons.Replacethe breakerplate assemblyif it is
defective.
The breaker point assembly andcondenserif so equipped shouldbe
replacedwheneverthe distributoris overhauled.
Inspect all electrical wiring forfraying,
breaks,etc.,andreplaceanythat arenot in goodcondition.
Check the distributor base forcracksor other damage.
Check the diaphragm housing,bracketand rod for damage.Checkthe
vacuum line fitting for strippedthreadsor other damage. Test
thevacuumfittings, caseanddiaphragmfor leakageasexplainedunder
"Distributor Tests".Replaceall defectiveparts.
197
-
9-22 198
PART, DUAL
LADVANCE DISTRIBUTORS
Section Page Section Page1 Description and Operation 9-22 3
Removal and Installation 9-23
2 In-Car Adjustments and Repairs 9-22 4 Major RepairOperations
9-24
fl DESCRIPTION AND OPERATIONThe dual advancedistributor Fig.
1 has two independentlyoperatedsparkadvancesystems.A
centrifugaladvancemechanismis locatedbelowthe
stationarysub-plateassemblyanda vacuum operated spark
controldiaphragmis locatedon the side ofthe distributor base. As
speed increases,the centrifugalweightscausethe cam to advanceor
moveaheadwith respectto the distributor driveshaft. The weights
turn the cam bymeansof a stop plate that has twoslots, which fit
over pins in the
weights. The slots determine themaximum amount of advance,andthe
rate of advanceis controlled bycalibratedsprings.
The vacuum advancemechanismhasaspring-loadeddiaphragmwhichis
connected to the breaker plate.The spring-loaded side of the
diaphragm is airtight and is connectedthrougha vacuumline to
thecarburetor throttle bore. Whenthe throttleplatesopen, the
distributor vacuumpassageis exposedto manifold vacuum, which
causesthe diaphragmto
move against the tension of thespring. This action causesthe
movable breaker plate to pivot on thestationary sub-plate. The
breakerpoint rubbing block, which is positioned on the opposite
side of thecamfrom the pivot pin, then movesagainstdistributor
rotation and advancesthesparktiming. As themovable breaker plate is
rotated fromretardposition to full advanceposition, the dwell
decreasesslightly.This is becausethe breaker pointrubbingblock
andthe camrotateondifferent axes.
U IN-CAR ADJUSTMENTS AND REPAIRSDISASSEMBLY
REMOVAL OF COMPONENTS
1. Removethe primary wire fromthe coil or the
distributor-transistor
lead from the quick disconnect.Unsnap the distributor cap
retainingclips, lift the distributor cap off thedistributor
housing,and position thecap out of the way.
2. Loosen the nut and pull thevacuum line out of the
diaphragmassembly.
3. Lift the rotor off the cam.4. Removethe spring clip
securing
STATIONARYSUB-PLATE
MOVEABLE
HOUSING
SHAFT
OILER DRIVEPIN-ø4 OIL SEALGEAR
COLLAR PIN
STOP
BREAKER POINTASSEMBLY
CONDENSER
CLAMP
SPRING
SPRING WASHER
FLAT WASHER
LUBRICATING WICK
RETAINER
FIG. i-Typical Dual Advance Distributor
VACUUM CONNECTION
81380-B
-
PART 9-2-DUAL ADVANCE DISTRIBUTORS 9-23
the diaphragmlink to the movablebreaker plate. Disconnect the
diaphragmassemblyfrom the distributor housing. Lift the
diaphragmlinkoff the pin and remove the diaphragmassembly.
5. Working from the inside of thedistributor, removethe primary
ordistributor-transistorlead wire bypulling it throughthe openingin
thedistributor.
6. Remove the two retainingscrews and lift the entire
breakerplate assemblyout of the distributorhousing.
7. Lift the lubricating wick out ofthe cam. Using needle nose
pliers,removethe camretainerandlift thecamoff the distributor
shaft.
8. Lift theupper thrust washeroffthe distributor shaft.
Carefully unhook and remove the distributorweight springs. Mark
each springand the adjusting bracket to whichit is attached.Lift
the weights outof the housing.
DIAPHRAGM AND BREAKERPLATE ASSEMBLY
1. Removethevacuumconnectionandgasket,then removethecalibrating
washers,return spring and stop.
2. Removethe retainingscrewandlift the condenserif so
equippedoff thebreakerplate Fig. 1.
3. Removethe retainerandwashers securing the movable
breakerplate to the stationarysub-plate.
ASSEMBLY
DIAPHRAGM AND BREAKERPLATE ASSEMBLY
1. Install the breaker point assembly on the
breakerplate.Positiona new condenserif so equippedand secureit in
place with the retaining screw.
2. Install the stop, return springand calibration washers, then
position a new gasket on the vacuumconnection. Install and tighten
thevacuum connection.
INSTALLATION OFCOMPONENTS
1. Install the weights in thehousing, theninstall thedistributor
weightsprings on the adjusting bracketsfrom which they were
removed.Install the upperthrust washeron thedistributor shaft.
2. Fill the grooves in the upperportion of the distributor shaft
withdistributor cam lubricant. Positionthe camon the distributor
shaft andinstall the cam retainer. Apply alight film of distributor
cam lubricant to the cam lobes. Install thewick in the cam
assembly.Saturatethe wick with SAE lOW engineoil.
3. Position the stationary sub-plate in the distributor. Install
oneend of the ground wire under theplate retaining screw closest to
thediaphragmmounting flange.
4. Positiontheentirebreakerplate
assembly in the distributor housingand securein place on the
sub-plateby installing the washers and retainer. Be sure the
protrudingedges of the spring washer arefacing upward.
5. Attach the ground wire to thebreaker point attaching screw
farthest from the breakerpoint adjustment slot. Working from inside
thedistributor housing,passthe primaryor distributor-transistor
lead wireassemblythrough the opening in thedistributor body. From
outside thedistributor, pull the wire throughtheopening until the
locating stop isflush with the inside of the distributor.
6. Connectthe condenserwire ifso equippedandthe primaryor
distributor-transistor lead wire to thebreakerpoints.
7. Position the diaphragmassembly and hook the diaphragm
linkover the pin on the breaker plate.Install the diaphragm
assembly retaining screws.Securethediaphragmlink with a spring
retainer.
8. Adjust the breakerpoint springtension, align the
breakerpoints andadjust thebreakerpoint gap. Checkthe breaker point
dwell and resistance. Check the centrifugal andvacuum advance refer
to "Dis-:tributor Tests".
9. Install the rotor anddistributorcap.
10. Connect the primary or distributor-transistor wir’e.
REMOVAL AND INSTALLATION
REMOVAL
1. On a conventional ignition system, disconnectthe primary wire
atthe coil. On a transistor ignitionsystem, disconnect the
distributor-transistor lead from the quick disconnect.Disconnect
the vacuumadvance line at the distributor. Remove the distributor
cap.
2. Scribe a mark on the distributor body and engineblock
indicatingtheposition of the body in theblock,andscribe anothermark
on thedistributor body indicatingthe positionof the rotor. These
marks can beused as guides when installing thedistributor in a
correctly timed engine.
3. Remove the distributor holddown cap screw and clamp. Lift
thedistributor out of the block.
INSTALLATION
The distributor installation isshownin Fig. 2.
1. If the crankshaft was rotatedwhile the distributor was
removedfrom the engine, it will be necessaryto time the
engine.Rotatethecrankshaft until No. 1 piston is on TDCafter
thecompressionstroke. Alignthe TDC mark on thetiming pointerwith
the timing pin on the crankshaft damper.Position the distributor in
the block with the rotor atthe No. 1 firing position.
Make sure the oil pump intermediateshaft properly
engagesthedistributor shaft. It may be necessary to crank the
engine with thestarter, after the distributor drivegearis partially
engaged,in order
199
F 1G. 2-DistributorInstallation
to engagethe oil pump intermediate shaft.
-
9-24 GROUP 9-IGNITION SYSTEM 200
Install, but do not tighten, the the mark previously scribed on
the coil. On a transistorignition system,retaining clamp and screw.
Rotate distributor body, and the markson
connectthedistributor-transistorleadthe distributor body
counterciock- thedistributorbody andengineblock to the quick
disconnect.wise until the breakerpointsarejust in alignment.
Install the retaining 5. Check the ignition timing withstarting to
open. Tighten the clamp, clamp, a timing light and adjust if
neces
2. If the crankshafthasnot been 3. Install the distributor cap.
sary. Connectthe vacuum line, androtated, position the distributor
in 4. On a conventionalignition sys- check the advancewith the
timingthe block with the rotor alignedwith tern, connecttheprimary
wire to the light when the engineis accelerated.
MAJOR REPAIR OPERATIONS
BENCH DISASSEMBLY
1. Remove the distributor andplaceit in a vise.
2. Removethe rotor. Removethespring clip securing the
diaphragmlink to the movable breaker plate.Disconnectthe
diaphragmassemblyfrom the distributorbase.
3. Lift the diaphragmlink off thepin and remove the
diaphragmassembly.
4. Disconnectthe primary or distributor-transistorlead wire and
thecondenser wire if so equippedfrom the breakerpoint terminal.
5. Working from the inside of thedistributor, remove the primary
ordistributor-transistor lead wire bypulling it throughthe opening
in thedistributor.
6. Remove the condenser if soequipped.
7. Removethe breaker point assembly.
8. Remove the lubricating wick.Using needlenosepliers,
removethecamretainer.
9. Remove the movable breakerplate spring
retainerandwashers.
10. Remove the stationary sub-plate retaining screws. Remove
thesub-plate,breakerplate and cam asan assembly.
11. Remove the upper thrustwasher.
FIG. 3-Gear PinRemoval or Installation
12. Carefully unhook and removethe distributor weight springs.
Markeach spring, bracket and adjustingpost to which it is
attached.
13. Removethe weights.14. Remove the distributor cap
clamps.15. If the gear and shaft are to
be used again, mark the gear andshaft so that the pin holes can
beeasily aligned for assembly. Removethe gear roll pin Fig. 3,
thenremovethe gear Fig. 4.
16. Remove the shaft collar rollpin Fig. 5.
17. Invert thedistributorandplaceit on a support plate in a
positionthat will allow the distributor shaftto clear the support
plate,and pressthe shaft out of the collar andthedistributor
housing Fig. 6.
18. Remove the distributor shaftbushing Fig. 7. Remove the
oilsealfrom the distributor housing.
FIG. 5-Collar RetainingPin Removal or Installation
BENCH ASSEMBLY
ORIGINAL ShAFT AND GEAR
1. Oil the new bushing, and installit on the bushing
replacertool. Install the bushing Fig. 8. When thetool bottoms
againstthe distributorbase, the bushing will be installedto the
correctdepth.
2. Burnish the bushing to thepropersize Fig. 9.
3. Oil the shaft and slide it intothe distributor body.
4. Place the collar in position onthe shaft and align the holes
in thecollar and shaft, then install a newpin Fig. 10. Install the
distributorcap clamps.
5. Check the shaft end play witha feeler gauge placed between
the