Index
Figure Index
General Troubleshooting
GENERATING CIRCIT
Generating Circuit
Periodic Servicing
Checks and Adjustments On the Vehicle
Servicing of Units Off the Vehicle
STARTING CIRCUT
Starting Circuit
Periodic Servicing
Checks and Adjustments On the Vehicle
Servicing of Units Off the Vehicle
IGNITION CIRCUT
Ignition Circuit
Periodic Servicing
Checks and Adjustments On the Vehicle
Servicing of Units Off the Vehicle
Troubles and Remedies
Specifications
Assembly Manual
Figure Index
1955
Fig. 1 - Generating Circuit Diagram
Fig. 2 - Battery
Fig. 3 - Generator Cross Section
Fig. 4 - Generator Circuit
Fig. 5 - Regulator
Fig. 6 - Checking Generating Circuit Resistances
Fig. 7 - Testing Specific Gravity of Battery
Fig. 8 - Battery Capacity Test
Fig. 9 - Checking Voltage Regulator Setting
Fig. 10 - Regulator Adjusting Screws
Fig. 11 - Contact Between Regulator Spring Support and Adjusting Screw
Fig. 12 - Voltage Regulator Correction Factors
Fig. 13 - Checking Cutout Relay Closing Voltage
Fig. 14 - Adjusting Cutout Relay Checking Voltage
Fig. 15 - Shorting Out Voltage Regulator
Fig. 16 - Checking for Oxidized Contact Points
Fig. 17 - Generator Installed
Fig. 18 - Removing Brush Leads
Fig. 19 - Exploded View of Generator
Fig. 20 - Removing Drive End Frame and Armature
Fig. 21 - Exploded View of Drive End Frame Assembly
Fig. 22 - Removing Power Steering Generator Rear Bearing
Fig. 23 - Checking Brush Spring Tension
Fig. 24 - Armature Test for Shorts
Fig. 25 - Armature Test for Ground
Fig. 26 - Armature Test for Open Circuit
Fig. 27 - Field Coil Test for Open Circuit
Fig. 28 - Field Coil Test for Ground
Fig. 29 - Positive Terminal Test for Ground
Fig. 30 - Positive Brush Test for Ground
Fig. 31 - Installing Power Steering Generator Rear Bearing
Fig. 32 - Motoring the Generator
Fig. 33 - Regulator Installed
Fig. 34 - Cleaning Regulator Contact Points
Fig. 35 - Use of the Riffler File
Fig. 36 - Adjusting Cutout Relay Air Gap
Fig. 37 - Adjusting Cutout Relay Point Opening
Fig. 38 - Adjusting Regulator Air Gap
Fig. 39 - Relationship of Regulator Parts
Fig. 40 - Starting Motor Cross Section
Fig. 41 - Starting Motor Circuit
Fig. 42 - Overrunning Clutch Mechanism
Fig. 43 - Solenoid Operation
Fig. 44 - Starting Motor and Solenoid Installed
Fig. 45 - Starting Motor Parts Layout
Fig. 46 - Pulling Field Frame from Armature
Fig. 47 - Exploded View of Armature and Overrunning Clutch Assembly
Fig. 48 - Driving Retainer off Snap Ring
Fig. 49 - Armature Test for Shorts
Fig. 50 - Armature Test for Ground
Fig. 51 - Field Coil Test for Open Circuit
Fig. 52 - Field Coil Test for Ground
Fig. 53 - Forcing Snap Ring Over Shaft
Fig. 54 - Forcing Snap Ring into Retainer
Fig. 55 - Exploded View of Solenoid
Fig. 56 - Adjusting Pinion Clearance
Fig. 57 - The Ignition Circuit
Fig. 58 - Six Cylinder Distributor
Fig. 59 - Eight Cylinder Distributor Cross Section
Fig. 60 - Cross Section of Movable Breaker Plate Assembly
Fig. 61 - Centrifugal Advance Mechanism
Fig. 62 - Ignition Coil
Fig. 63 - Ignition Circuit Checks
Fig. 64 - Material Transfer, Negative to Positive Point
Fig. 65 - Material Transfer, Positive to Negative Point
Fig. 66 - Inaccurate Gauging of Rough Points
Fig. 67 - Alignment of Points
Fig. 68 - Checking Breaker Arm Spring Tension
Fig. 69 - Adjusting Breaker Lever Spring Tension
Fig. 70 - Top View of Six Cylinder Distributor
Fig. 71 - Six Cylinder Distributor Primary Terminal
Fig. 72 - Top View of Eight Cylinder Distributor
Fig. 73 - Eight Cylinder Distributor Contact Support Assembly
Fig. 74 - Six Cylinder Distributor Installed
Fig. 75 - Removing Six Cylinder Distributor
Fig. 76 - Six Cylinder Distributor Parts Layout
Fig. 77 - Eight Cylinder Distributor Parts Layout
Fig. 78 - Eight Cylinder Distributor and Coil
Fig. 79 - Exploded View of Movable Breaker Plate Assembly
Fig. 80 - Measuring Stabilizing Spring Tension
Fig. 81 - Measuring Friction Between Plates
Fig. 82 - Installing Eight Cylinder Distributor
Fig. 83 - Spark Plug Wire Installation
Fig. 84 - Ignition Switch Installation
Fig. 85 - Setting Spark Plug Gap
Fig. 86 - Engine Electrical Special Tools
1956
Fig. 1 - Generating Circuit Diagram
Fig. 2 - Battery
Fig. 3 - Regulator
Fig. 4 - Checking Generating Circuit Resistance
Fig. 5 - Checking Voltage Regulator Setting
Fig. 6 - Regulator Adjusting Screws
Fig. 7 - Contact Between Regulator Spring Support and Adjusting Screw
Fig. 8 - Voltage Regulator Correction Factors
Fig. 9 - Checking Cutout Relay Closing Voltage
Fig. 10 - Checking Current Regulator Setting
Fig. 11 - Opening Top of Container
Fig. 12 - Removing Top of Container
Fig. 13 - Cutting hole in plastic
Fig. 14 - Pouring Electrolyte into Battery
Fig. 15 - Rinsing Electrolyte from Plastic Bag Before Disposal
General Trouble-Shooting
General Trouble-Shooting Notes
Battery
Generator
Regulator
Starting Motor and Solenoid
Ignition System
General Trouble-Shooting Notes
The wiring diagram for the engine electrical system is included with body and chassis electrical circuit diagrams in Section 12-Chassis Electrical.
Following are a series of quick checks, which are designed
to assist the serviceman in locating trouble within the various
components of the engine electrical system. Additional checks,
adjustments and overhaul of these components are also described
elsewhere in the Section 12-Chassis
Electrical. (see Index) and should be made where required.
Battery
Measure the voltage between the "BAT" terminal of the regulator and ground at (1) idle speed, and (2) medium engine speed. The voltage should be higher at a medium engine speed than it is at idle speed. If it is not and the generator passes its tests above, make a complete check of the regulator. If voltage is higher at medium speed, the voltage regulator setting still may require adjustments as discussed previously under Steps 3 and 4 of BATTERY if the battery remains undercharged or uses too much water.
The following checks may be made if the specific gravity of the battery is 1.215 or higher.
If the engine does not run, the ignition system may be at fault if:
If these checks indicate trouble in the ignition system, follow
the procedure outlined under Ignition Circuit-Checks and Adjustments on
the Vehicle. This procedure may also be helpful in locating trouble in
the ignition system if the car runs but not satisfactorily also see
Section 6 Tune-Up .
Generating Circuit
Description and Operation
Battery
Generator
Regulator
Generator Telltale Light
Description and Operation
The generating circuit includes the battery, generator, regulator,
generator telltale light, and necessary wiring to connect these parts,
The purpose of this system is to convert just enough mechanical energy
from the engine into electrical energy to supply all electrically
operated units and keep the battery fully charged. The simplified wiring
diagram shown in Fig. 1
illustrates this circuit.
Battery
A 53 ampere-hour battery, shown in Fig. 2, with microporus rubber separators, new grid alloy and molded polystyrene vent plugs replaces the former battery which was a 50 ampere-hour model with wooden separators. The improvements will lengthen battery life and improve performance, but service instructions will remain the same except as noted under Servicing of Units off the Vehicle.
Batteries are equipped with "Visual Level" cell covers to facilitate checking electrolyte level and lessen the possibility of overfilling the battery. These covers have a long, circular, tapered vent well with two small vertical slots diametrically opposite. Viewed from above, with the battery vent plugs removed, the lower end of the vent well appears as a ring with small portions of the circumference missing. As water is added to the cell, the surface of the rising liquid contacts the slotted lower end of the vent well causing a distortion of the reflecting surface of the liquid which is very noticeable. Thus, the lower end of the vent well serves as a reference point in determining proper electrolyte level. The cell is properly filled when the surface of the electrolyte touches the bottom of the vent well. If some overfilling occurs, the amount can be estimated readily by the height of liquid in the vent well itself.
The battery has three major functions to perform on the vehicle.
In order for the battery to continue to function it is necessary that the current withdrawal from the battery be balanced by current input from an xternal source so that the battery is maintained in a charged condition. The efficiency of a battery, therefore, is in direct proportion to its state of charge. To obtain the maximum efficiency, whatever amount of current is withdrawn from or generated by the battery must be compensated for by running the generator long enough to restore the battery to the condition known as "Charged".
The generator (Fig. 3) is a 12-volt, 25-ampere, two brush shunt unit. The extruded frame of the generator has two pole shoes attached to it 180° apart, around which are located the field coils. The armature is centered between the pole shoes and is supported by a ball bearing at the drive end and a porous bronze bushing at the commutator end. On power steering models, the commutator end of the armature is used to drive the power steering pump and is supported at this end by a ball bearing in lieu of a bronze bushing. The end plates have openings for circulation of air for cooling. Air is circulated through the generator by the combined pulley and fan that are mounted on the front end of armature shaft. Brush holders mounted inside the generator housing hold the brushes in correct position under spring tension against the armature commutator. One brush is grounded to the frame while the other is insulated from the frame.
The insulated brush is connected to the positive "A" terminal of the generator and to one terminal of the field coils (Fig. 4). The other end of the field coils is connected to the insulated field "F" terminal of the generator.
In order for the generating system to operate the positive wire
from the generator armature terminal must be connected to the generator
(GEN) terminal of the regulator, the wire from the field terminal of the
generator connected to the field (F) terminal of the regulator and the
wire from the battery to the battery (BAT) terminal of the regulator (Fig. 1). Generator output is controlled by a current and voltage
regulator.
Regulator
The three-unit, 12 volt regulator ( Fig. 5) provided on all passenger car models is designed for use with a negative grounded battery and a shunt type generator. The regulator, which is mounted on the fender skirt baffle above the horn relay (Fig. 33), contains a cutout relay, a voltage regulator unit, and a current regulator unit.
Cutout Relay
The purpose of the cutout relay is to close and open the charging circuit between the generator and battery. When the generator voltage reaches the value for which the cutout relay is adjusted, the contact points close and current flows from the generator toward the battery. When generator voltage falls below battery voltage, the contact points open to prevent battery discharge through the generator while the engine is idling or stopped.
Voltage Regulator
The purpose of the voltage regulator unit is to limit the system voltage to a safe maximum. Vibrating contacts of the voltage regulator limit voltage by intermittently inserting resistance in the generator field circuit as required. With system voltage properly limited, electrical components are protected and the battery is not subject to excessive overcharging.
The voltage regulator (Fig. 3) has been made waterproof by the addition of a rubber seal between the cover and the base. Cover screws have been located on the flange on either end of the cover allowing the use of shorter, easier to install, cover screws. The regulator has been relocated to a point on the left fender skirt nearer the center of the electrical system. The unit is thus more accessible for servicing and the use of shorter wires is permitted. All changes in service instructions are covered in Checks and Adjustments on the Vehicle.
Current Regulator
The purpose of the current regulator unit is to prevent
overheating of the generator armature by limiting generator output.
Vibrating contacts of the current regulator limit current output by
intermittently inserting resistance in the generator field circuit as
required.
Generator Telltale Light
The generator telltale light, located in the instrument cluster, is connected in a circuit with the battery and the generator (Fig. 1). With the ignition switch turned ON and engine off, the indicator will light up denoting no generator output to the system, in which case the battery is supplying all the demands (battery discharging).
As the generator voltage is increased after starting, it will oppose the battery voltage to the telltale light and close the cutout relay points, causing the indicator light to go out. With the cutout relay points closed, generator output is supplied to the system.
With the indicator light off current may be flowing to or from the battery depending upon the loads imposed upon the system and the generator output at any particular time.
Therefore the telltale light functions primarily as an indicator
of generator output, not necessarily of current flow to or from the
battery as in the case of the ammeter. If the indicator light is not
functioning properly, see Generating Circuit-Checks and Adjustments on
the Vehicle in this section. Replacement of the generator light is
described in Section 12-Chassis Electrical.
Periodic Servicing
Liquid level in the battery should be checked at least every 1,000 miles or once every two weeks. If the liquid level is found to be low, water should be added to each cell until the liquid level rises to the bottom of the vent well. Do not overfill! Distilled water, or water passed through a "demineralizer," should be used for this purpose in order to eliminate the possibility of harmful impurities being added to the electrolyte. Many common impurities will greatly shorten battery life. Do not add any substance to the electrolyte except water.
The external condition of the battery and the battery cables should be checked periodically. The top of the battery should be kept clean and the battery hold-down bolts should be kept properly tightened. Particular care should be taken to see that the tops of 12-volt batteries are kept clean of acid film and dirt because of the high voltage between the battery terminals. For best results when cleaning batteries, wash first with a dilute ammonia or soda solution to neutralize any acid present and then flush off with clean water. Care must be taken to keep vent plugs tight so that the neutralizing solution does not enter the cell. The hold-down bolts should be kept tight enough to prevent the battery from shaking around in its holder, but they should not be tightened to the point where the battery case will be placed under a severe strain.
To insure good contact, the battery cables should be tight on the battery posts. If the battery posts or cable terminals are corroded, the cables should be disconnected and the terminals and clamps cleaned separately with a soda solution and a wire brush. After cleaning and before installing clamps, apply a thin coating of petrolatum to the posts and cable clamps to help retard corrosion.
GENERATOR
The hinge cap oilers of the generator should be filled with light engine oil once at each vehicle lubrication period. However, if the oil reservoir in the commutator end frame should become exhausted through failure to add oil at each vehicle lubrication period, the oil cup should be filled three times consecutively, allowing time between fillings for the oil to saturate the wick. The hinge cap oiler on the drive end frame, however, never should be filled more than once at each lubrication period.
Periodic servicing of the generator should include an inspection of the commutator and brushes for cleanliness and wear. If the commutator is dirty it should be cleaned as outlined under Generating Circuit Checks and Adjustments on the Vehicle in this section. If the brushes are worn down less than half their original length, they should be replaced.
REGULATOR
Normally, periodic servicing of the regulator is not required.
However, it may occasionally be necessary to clean the regulator contact
points as outlined under Generating Circuit-Servicing of Units Off The
Vehicle.
Checks and Adjustments on the Vehicle
Generator Telltale Light
Wiring
Battery
Regulator
Voltage Regulator Setting
Cutout Relay Closing Voltage
Current Regulator Setting
Generator
Generator Telltale Light
If the indicator light stays on after the engine is started and run above idle speed, the generator should be checked. If light stays on at idle only, check for a low idle speed. Also check to see that the generator field is properly grounded by connecting a jumper wire from generator field terminal to ground with engine running at medium speed. If light goes out after connecting jumper wire, then cause of trouble is an improperly grounded generator field circuit.
If the light does not go on with the ignition switch ON and
engine OFF, the indicator bulb should be checked and the telltale light
circuit inspected for the possibility of an open circuit or loose
connections.
Wiring
Excessive voltage drop (resistance) in the charging circuit tends to keep the battery in an undercharged condition. To check for excessive voltage drop (resulting from loose connections or other high resistance) in the generating circuit, make connections as shown in Fig. 4 and proceed as follows:
If excessive resistance is found, check the wiring for defects,
and replace if necessary. Correct poor ground connections and clean and
tighten all connections.
Battery
Three battery checks are described herein to determine in a minimum amount of time the condition of the battery.
If a battery failure is encountered the cause may lie outside the battery itself. DO NOT BE SATISFIED TO MERELY RECHARGE OR REPLACE IT. FIND THE CAUSE OF FAILURE AND PREVENT RECURRENCE OF TROUBLE.
State of Charge (Hydrometer Test)
The hydrometer test is merely a means of determining the state of charge of the battery. This test will not necessarily indicate whether the battery is able to perform its normal functions, such as starting.
To determine whether a battery is a good battery, regardless of its state of charge, proceed with the Battery Capacity Test.
Battery Capacity Test
This test is one means of determining whether a battery is functioning efficiently to the degree where it can be relied upon to perform all of its duties properly in the vehicle.
A 12 volt battery that will maintain 9.0 volts or better during a battery capacity test should be considered a good battery. To make this test use equipment that will apply a heavy electrical load to the battery with a carbon pile or other suitable means.
NOTE: If test equipment is not available for loading battery, the starting motor may be used as a load.
In cases where a voltage of less than 9.0 volts is obtained in the Battery Capacity Test described above, an accurate test using a volt-meter and a fast charger will quickly establish in three to four minutes whether a battery is good or bad even when the battery is in a discharged condition.
This procedure determines the condition of charged or discharged batteries by following the principles that:
This test should not be used if battery temperature is below 60 degrees F.
If battery temperature is above 60 degrees F., add battery water, if necessary, and proceed with the Three Minute Battery Test described on the following page.
CAUTION: Do not make this test, which is recommended for
discharged batteries, if voltage obtained in battery capacity test is
9.0 or more. A charged battery will not accept 40 amperes without an
excessively high voltage.
Regulator
Four regulator electrical checks can be made on the car-the settings of the cutout relay, voltage regulator, and current regulator, and a check for oxidized regulator contact points. Mechanical checks and adjustments requiring removal of the regulator from the car are discussed under Generating Circuit-Servicing of Units Off the Vehicle.
The regulator must have the cover in place and must be at operating temperature when the electrical settings are. checked. Operating temperature shall be assumed to exist after not less than 15 minutes of operation at a charging rate of 8-10 amperes. For best results, the electrical checks should be made in the following order:
The following procedures are required for making each of these
checks:
Voltage Regulator Setting
A method for checking and adjusting the voltage regulator setting is discussed below. However, it is seldom necessary to check and adjust the voltage regulator setting so long as (1) the battery remains satisfactorily charged without excessive use of water and (2) there is no evidence of damage to lights or other voltage-sensitive equipment.
To check the voltage regulator setting, proceed as follows:
CAUTION: Final adjustment should always be made by increasing spring tension to assure contact between the screw head and spring support. Sometimes the spring support does not follow the screw head as spring tension is decreased, and it will be necessary to bend the spring support up to insure contact between the spring support and screw head before final adjustment is completed (Fig. 7). Failure of the voltage regulator unit to "hold" its setting usually results from (1) setting or checking the voltage regulator at other than operating temperature, and (2) the screw head not touching the spring support after final adjustment is complete.
Before taking the reading after each adjustment, replace the regulator cover as quickly as possible and cycle the generator. The engine should be stopped while removing and replacing the regulator cover to reduce the chances of causing a short circuit.
Voltage Regulator vs. Ambient Temperature
The voltage regulator "Normal Range" setting specifications described in this section refer to a regulator which has been brought to a stabilized operating temperature at an ambient temperature of 125 Deg. F. (Ambient temperature is the temperature of the air surrounding the regulator approximately 1/4 of an inch from the regulator cover.) Since the stabilized operating temperature of the regulator varies with the ambient temperature, the voltage regulator "Normal Range" setting varies accordingly. Fig. 8 llustrates the normal range settings at various ambient temperatures and how the voltage regulator setting varies at different ambient temperatures as indicated by the vertical line.
Through the use of the table shown in Figure 8 it is possible to determine correct voltage readings at any ambient temperature from 45Deg. to 165 Deg.F.
When the "corrected" voltage regulator setting falls within the normal range given in the specifications and the battery condition has been satisfactory after a reasonable period of operation with this setting, the voltage regulator setting should not be disturbed.
When the "corrected" voltage regulator setting falls inside or outside the normal range given in the specifications but battery condition has been unsatisfactory after a reasonable period of operation with this setting, tailor the voltage regulator setting as described under Tailoring the Voltage Regular Setting below.
Tailoring the Voltage Regulator Setting
The desired voltage regulator setting is that which keeps the battery in a satisfactory state of charge without causing excessive water usage (as evidenced by water consumption exceeding one ounce per cell each 1000 miles). In order to obtain the desired setting, tailor the voltage regulator setting as follows:
NOTE: Avoid "corrected" settings above 14.8 volts as these may cause damage to lights and other voltage-sensitive equipment.
It rarely will be found necessary to use a voltage regulator setting outside the normal range in order to correct battery conditions. Batteries which do not respond to voltage regulator settings within the normal range usually will be found to be (1) batteries used in cars that are operated consistently at low speeds or in heavy traffic, or (2) batteries that have abnormal charging characteristics.
On new cars or on other applications where no battery history is available, any "corrected" voltage regulator setting found within the normal range may be considered satisfactory unless local conditions or subsequent battery performance indicate the need for tailoring the voltage regulator setting.
Any setting that falls within the, allowable limits given in the specifications is satisfactory so long as the setting is at least 0.5 volt below the voltage regulator setting. It is seldom necessary to check the closing voltage of the cutout relay as long as the relay functions to close and open the charging circuit.
Any setting that falls within the allowable limits given in the specification is satisfactory. It is seldom necessary to check the setting of the current regulator unless the generator armature shows signs of overheating.
Check for Oxidized Regulator Contact Points
NOTE: Oxidized regulator contact points may be the cause of a low generator output or a discharged battery.
When belt tension is properly adjusted but the generator does not perform satisfactorily on the car, inspect the commutator. If the commutator is dirty, clean it by holding No. 00 sandpaper or a cleaning stone against it while the generator is operating at idle speed. Never use emery cloth to clean the commutator. If this does not satisfactorily improve generator performance the generator should be removed from the car for a thorough check as outlined under Generating Circuit-Servicing of Units Off the Vehicle.
Battery
Generator
Regulator
Radio By-Pass Condensers
Polarizing the Generator
Battery
Testing
Batteries may be tested off the vehicle in the same manner as described under Generating Circuit-Checks and Adjustments on the Vehicle.
Common Causes of Battery Failure
When a battery fails, the cause of failure may lie outside the battery itself. For this reason when a battery failure is encountered, do not be satisfied to merely recharge or replace it. Find the cause of failure and prevent recurrence of the trouble.
Listed below are some of the common causes of battery failure:
Charging
Batteries removed from the car for charging should be charged continuously at a low rate until fully charged. Batteries may be safely slow-charged at a rate in amperes equal to 7% of the battery's ampere-hour capacity. Ex. 7% of 53 A.H. = 3.7 amperes. This is called the "normal" charge rate. The battery is fully charged when specific gravity readings taken at hourly intervals show no increase during three consecutive readings. Badly sulphated batteries may require a continuous slow charge for 48 hours or more before a rise in gravity readings occurs. If the specific gravity reading of any cell fails to reach 1.250 (corrected to 80°F.) or if there is a variation of more than 25 points between cells after thorough slow charging, replace the battery.
Although the slow-charge method is recommended for charging all batteries, discharged batteries in otherwise good condition (see Battery Capacity Test) may be given a "boost" with a fast charger if time does not permit complete slow charging. When using a quick charger, it must be remembered that the battery is only receiving a partial charge and that the battery electrolyte temperature must not be allowed to exceed 120°F. If the battery heats excessively, quick charging must be discontinued.
New Vehicles in Stock
Before a new car is delivered to a customer, make sure the specific gravity of the battery electrolyte measures at least 1.250-preferably higher. Under no circumstances should acid be added to a new battery to increase the specific gravity of the electrolyte.
New Batteries in Parts Stock
Removal
Brush Replacement
If brushes are worn to half their original length they should be replaced.
Disassembly
Refer to Fig. 19 for an exploded view of the generator.
Cleaning and Inspection
With the generator completely disassembled, except for removal of field coils, the component parts should be cleaned and inspected as described below. Field coils need be removed only where defects in the coils are indicated by the tests described below, in which case the pole shoe screws should be removed and the pole shoes and field coils disassembled. Any defective parts should be replaced or repaired (see Generator Repairs).
Testing Generator Parts
Refer to Fig. 4 for generator internal circuit diagram. Use a test lamp capable of detecting high resistance grounds.
Check armature for shorts by placing on growler and with hack saw blade over armature core, rotate armature (Fig. 24). If saw blade vibrates, armature or commutator is shorted. Recheck after cleaning between the commutator bars and if saw blade still vibrates, armature is shorted and must be replaced.
Using test lamp, place one test prod lead on armature core and other on each commutator bar (Fig. 25). If lamp lights, armature is grounded and must be replaced.
Check the armature for open circuits by making a bar-to-bar check as shown in Fig. 26. Inconsistent variations in reading indicate an "open" armature.
Using test lamp, place one test prod lead on field terminal on generator frame and the other test prod lead on the end of the field coil lead to the armature terminal (Fig. 27). If lamp does not light, the field coils are open and must be replaced (unless a loose soldered connection is found at the field terminal).
Using a test lamp, place one test prod lead on ground (touch to generator frame) and other lead on field terminal on generator frame (Fig. 28). Be sure free end of field wire is not touching ground and field terminal insulation is not broken. If lamp lights, the field coils are grounded. If ground in field coils cannot be located or repaired, coils must be replaced.
Using a test lamp, place one test prod lead on generator positive armature terminal on generator frame, and place other lead on ground on generator frame (Fig. 29). Be sure loose end of terminal lead is not touching ground. If lamp lights, positive terminal insulation through generator frame is broken down and must be replaced.
Using a test lamp, place one test prod lead on the positive or insulated brush holder and the other lead on ground. If lamp lights the brush holder is grounded due to defective insulation at the frame (Fig. 30) .
Repairs
When an open soldered connection of the armature to commutator leads is found during inspection, it may be resoldered provided rosin flux is used for soldering.
CAUTION: Acid flux must never be used on electrical connections.
When inspection shows commutator roughness, it should be cleaned as follows:
If brush holders are damaged they can be replaced by special service units which are attached with screws and nuts.
Assembly
After all parts have been thoroughly tested and inspected and worn or damaged parts replaced, the generator should be reassembled. Pack ball bearings with high melting point ball bearing grease before assembly.
Installation
While electrical adjustments are made with the regulator on the car as outlined under Checks and Adjustments on the Vehicle, it is necessary to remove the regulator for cleaning contact points and adjusting air gaps on the three regulator units.
Removal
To remove the regulator it is merely necessary to disconnect the leads from the regulator terminals and remove the screws securing the regulator to the fender skirt baffle ( Fig. 33).
Inspection and Adjustment
Electrical settings must be checked and adjusted after making mechanical adjustments described below. Before installing regulator cover, make sure the rubber gasket is in place on the regulator base.
Cleaning Regulator Contact Points
Regulator contact points will not operate indefinitely without some attention. Dirty or oxidized contact points arc and burn, cause reduced generator output and run down batteries. It has been found that a great majority of all regulator troubles can be corrected by a simple cleaning of contact points plus possibly some readjustment. If the points are properly cleaned the regulator will be restored to normal operation. If improperly cleaned, improvement in performance will be small and only temporary.
To clean the contact points, remove cover and loosen the upper contact bracket mounting screws so that the bracket can be tilted to one side (Fig. 34). For greater accessibility in cleaning, the contact brackets may be removed. If removed great care must be exercised to reinstall them as described under Replacing Upper Contact Support Brackets.
Use a spoon or riffler file and file each point separately. Never use sandpaper or emery cloth to clean the contact points because particles of embedded grit in the regulator points will cause them to arc and corrode. Do not file contact points excessively.
The large flat contact point, located on the armature of both current and voltage regulator units , always develops a slight cavity (Fig. 35) and will require the most attention. It is not necessary to have a flat surface on this contact point, but a riffler file should be used to remove all oxides so that pure metal is exposed.
The small soft-alloy contact point, located on the upper contact support of current and voltage regulator units, does not oxidize. This contact point may be cleaned with crocus cloth, or other fine abrasive material, followed by a thorough wash with clean carbon tetrachloride to remove any foreign material remaining on the contact surface.
The upper contact support brackets may be replaced where desired. See Replacing Upper Contact Support Brackets.
Cutout Relay Air Gap and Point Opening
Voltage Regulator Air Gap
Current Regulator Air Gap
Replacing Upper Contact Support Brackets
Voltage or current regulator contact support brackets can be replaced by carefully noting the relationship of the parts as they are removed (Fig. 39). Note particularly that the connector strap is insulated from the voltage regulator contact mounting screws while it is connected to current regulator contact mounting screws. New insulators should always be used when install a contact support bracket since the old insulator may be distorted or damaged.
Replacing Springs
If it becomes necessary to replace the spiral spring on either the current or voltage regulator unit, the new spring should first be hooked on lower spring support and then stretched up until can be hooked at the upper end. Stretch the spring only by means of a screwdriver blade inserted between the turns. Do not pry the spring into place as this is likely to bend the spring supports. Aft installing a new spring, readjust the unit setting as already described.
Installation
The installation of radio by-pass condensers on the field terminal
of the regulator or generator will cause the regulator contact points to
burn and oxidize so that generator output will be reduced and a rundown
battery will result. If a condenser is found connected to either of
these terminals, remove the condenser and clean the regulator contact
points as previously explained. Never Connect Radio By-pass Condensers
to the Field Terminal of the Regulator or Generator.
Polarizing the Generator
After reconnecting leads, momentarily connect a jumper lead between
the "GEN" and "BAT" terminals of the regulator. This
allows a momentary surge of current to flow through the generator which
correctly polarizes it. Failure to do this may result in severe damage
to the equipment since reversed polarity causes vibration, arcing, and
burning of the relay contact points.
Starting Circuit
The starting circuit, which includes the starting motor, solenoid and battery, has only one function to perform-to crank the engine. The battery (see generating Circuit) supplies the energy, the solenoid completes the circuit to the starting motor, and the motor then does the actual work of cranking the engine.
The starting motor (Fig. 40) consists primarily of the drive mechanism, frame, armature, brushes, and field windings. The starting motors used on both six and eight cylinder engines are similar 12 volt extruded frame type units with pressed steel commutator end frames. A metal connector bar connects the fields directly to the solenoid terminal. Both motors have four poles and series fields. The four field coils are connected in series from the connector bar to the insulated brushes ( Fig. 41 ). The armature rotates in permanently lubricated bushings at each end. The motor brushes are mounted directly to the inside wall surface of the extruded section of the field frame. One grounded brush arm and one insulated brush arm are pivoted from each of the two brush holder supports with a single ribbon type spring applying tension to each pair of brushes.
The starter pinion in conjunction with an overrunning clutch, a compression spring, and a drive collar are mounted as an assembly on the splined part of the armature shaft. A shift lever, bolted at its fulcrum to the starting motor housing has a yoke at its lower end which straddles the drive collar, with integral bosses on its inner sides engaging the collar grooves. The upper end of the lever connects to adjustable solenoid plunger linkage. A pinion stop, consisting of a snap ring and retainer assembled on the armature shaft, takes all of the end thrust resulting from armature and pinion movement, while a thrust collar limits armature end play.
The overrunning clutch transmits cranking torque from the starting motor armature to the engine flywheel, but allows the drive pinion to rotate freely with respect to the remainder of the clutch assembly and armature when the engine begins to operate. This feature prevents the armature from being driven at excessive speed by the engine. The multiple spring and roller overrunning mechanism (Fig. 42) is located between the outer part of the clutch, which is attached to the pinion, and the inner part splined to the armature shaft. The armature shaft and clutch both have spiral springs, which transmit full cranking power only after the clutch pinion is fully engaged with the flywheel ring gear.
The magnetically operated solenoid switch closes and opens the circuit between the battery and cranking motor. It also shifts the drive pinion of the starting motor into mesh with the teeth on the engine flywheel so the engine can be cranked. To accomplish this action, a shift plunger, linked to the shift lever, is drawn into the solenoid when the solenoid windings are energized.
There are two windings in the solenoid, a pull-in winding, which is shorted out as the solenoid contacts close, and a hold-in winding which holds the plunger in the solenoid as long as the starting motor circuit is not broken. When the remote control switch on the instrument panel is closed, the battery energizes both the "pull-in" and "hold-in" coils, causing the plunger to pull the pinion into mesh with the flywheel teeth (Fig. 43). The plunger movement, continued, closes the switch contacts, thus permitting the starting motor to crank the engine. The "pull-in" coil draws a comparatively heavy current for a short interval. This is needed to engage the pinion. The "hold-in" coil also aids the "pull-in" coil. As soon as the solenoid switch is closed (and the pinion shifted), the "pull-in" coil is short circuited by the contacts in the starting motor circuit so that only the "hold-in" coil draws current.
No periodic lubrication of the starting motor or solenoid is required. Since the starting motor and brushes cannot be inspected without disassembling the unit, no service is required on these units between overhaul periods.
Although the starting motor cannot be checked against specifications on the car, a check can be made for excessive resistance in the starting circuit. Place a voltmeter across points in the cranking circuit indicated below and observe the reading with the starting switch closed and the motor cranking (distributor primary lead grounded to prevent engine firing).
From battery positive post To solenoid battery terminal
From battery negative post To starting motor housing
From solenoid battery terminal To solenoid motor terminal
If voltage drop in any of above checks exceeds 0.2 volt, excessive resistance is indicated in that portion of starting circuit and the cause of the excessive resistance should be located and corrected in order to obtain maximum efficiency in the circuit.
CAUTION: Do not operate the starting motor continuously for more than 30 seconds to avoid overheating.
When the solenoid fails to pull in, the trouble may be due to excessive voltage drop in the solenoid control circuit. To check for this condition, close the starting switch and measure the voltage drop between the BATTERY terminal of the solenoid and the SWITCH (S) terminal of the solenoid.
Starting Motor
Solenoid
Pinion Clearance Adjustment
Starting Motor
Removal
Disassembly
Cleaning and Inspection
With the starting motor completely disassembled, except for removal of field coils, the component parts should be cleaned and inspected as described below. Field coils need be removed only where defects in the coils are indicated by the tests described below, in which case the pole shoe screws should be removed and the pole shoes and field coils disassembled. Any defective parts should be replaced or repaired (see Repairs).
Testing Starting Motor Parts
Refer to Fig. 41 for starting motor internal circuit diagram. Use a test lamp capable of detecting high resistance grounds.
Check the armature for short circuits by placing on growler and holding hack saw blade over armature core while armature is rotated (Fig. 49). If saw blade vibrates, armature is shorted. Recheck after cleaning between the commutator bars. If saw blade still vibrates, replace the armature.
Place one lead on the armature core or shaft and the other on the commutator (Fig. 50). If the lamp lights, the armature is grounded and must be replaced.
Place one lead on each end of the field coil (Fig. 51). If the lamp does not light, the field coil are open and will require replacement.
Place one lead on the connector bar and the other on the field frame (Fig. 52). If the la lights, the field coils are grounded.
Repairs
When an open soldered connection of the armature to commutator leads is found during inspection, it may be resoldered provided rosin flux is used for soldering.
CAUTION: Acid flux must never be used on electrical connections.
When inspection shows commutator roughness, it should he cleaned as follows:
If brush holders are damaged, they can be replaced by special service units which are attached with screws and nuts.
Assembly
After all parts have been thoroughly tested and inspected and worn or damaged parts replaced, the generator should be reassembled.
After reassembly, a "Free Speed" check of the starting motor may be made if equipment is available. To make this check, connect a 12 volt battery in series with an ammeter to the starting motor terminal and ground. Use a mechanical drive type tachometer to determine the speed reached by the starting motor. Failure of the starting motor to perform according to the following specifications may be due to tight or dirty bushings, or high resistance connections.
Volts-10.3
Amperes-75 Max.
RPM-6900 Min.
Installation
Removal
Replacement of Contacts
Testing Current Draw of Windings
Refer to Fig. 55.
To check the current draw of the hold-in winding, connect a variable source of voltage (in series with an ammeter) to the switch terminal of the solenoid and ground. To check the current draw of both windings, ground the solenoid motor connector strap terminal, and connect a source of voltage (in series with an ammeter) to the switch terminal of the solenoid and ground. Current draw should be:
Hold-in Winding 18-20 Amperes at 10 Volts Both Windings 72-76 Amperes at 10 Volts
CAUTION: Either of the above checks must be completed in a minimum length of time to prevent heating of the solenoid windings. Heating will cause the current draw readings to be below the specifications which are based on a temperature of 80°F.
Installation
Description and Operation
Distributor
Coil and Resistor
Ignition and Starting Switch
Spark Plugs
Description and Operation
The basic function of the ignition circuit is to produce and deliver
high voltage surges to the correct spark plug at the correct interval of
time to fire the spark plug. The 12-volt ignition system in all 1955
Passenger car models provides adequate ignition reserve to meet all
performance levels. The ignition circuit (Fig. 57) includes the distributor, ignition coil, ignition
resistor, ignition switch, spark plugs, and the battery.
Distributor
Six Cylinder Engine
The distributor for the six cylinder engine (Fig. 58) is mounted on the right side of engine. It incorporates the distributor points which open and close to make and break the primary circuit, the condenser which prevents arcing at the points and aids in breaking down the magnetic field in the coil, the mechanical spark advance mechanism which advances and retards the spark with changes in engine speed, the distributor cap which has the terminals for high tension current distribution to the spark plugs and the rotor which distributes the high tension current to the terminals in the cap.
The vacuum spark control is attached to the distributor bracket and connects to the distributor. The diaphragm chamber is connected to the carburetor so that engine vacuum can advance the spark and also retard it when engine vacuum decreases on acceleration.
The distributor housing is designed to pilot down into the right side of cylinder block which supports the distributor. A drive gear is located near the lower end of shaft and meshes with a gear on the engine camshaft to drive the distributor shaft at camshaft speed. A plate fitted with pivot pins for the governor weights is attached near the top of the shaft. The weights are placed on the pivots, the cam assembly is placed over the top of shaft and the springs are installed (Fig. 61). A hold-down plate is then installed over the governor.
The stationary breaker plate, which is internally grounded, sets directly above the governor mechanism and is attached to the distributor housing. One distributor point and support sets over the pivot pin on the breaker plate and is held in place by a lock screw. The location of this point can be moved for point gap adjustment by loosening the lock screw and turning the eccentric adjusting screw as desired. The other point and arm assembly is fitted with an insulating bushing which pilots over the pivot pin. The breaker arm is fitted with a fiber block which extends out toward the cam. As the cam turns the lobes contact the fiber block and cause the points to open.
The condenser is attached to the breaker plate and the lead connected to the insulated terminal at the point where the breaker arm connects. This places the condenser across the breaker points. The rotor attaches to the top of the cam and turns at camshaft speed. The distributor cap sets on top of the housing with a positioning lug engaging a groove in the housing. Clamps hold the cap in position. The center terminal of the cap engages the spring contact of the rotor to transmit high tension current from the coil to the rotor. As the rotor turns the current can be transmitted to the different spark plug wire terminals.
Eight Cylinder Engine
The distributor for the eight cylinder engine (Fig. 59) functions basically the same as the six cylinder engine distributor, but differs primarily in the following design features.
The movable breaker plate on the eight cylinder distributor contains a bronze bearing assembled at its center. This bearing turns freely in the mating hole of the support plate. The movable plate is supported by three built-in, molded, anti-friction buttons or bearings which glide over the upper surface of the support plate as the movable plate is rotated (Fig. 60). The molded bearings are designed with a convex bearing surface for minimum friction. A lubricating felt, located between the two plates, supplies constant lubrication for these bearings and the center bearing. The felt also prevents dirt and dust particles getting on the bearing surfaces.
The two plates, and the lubricating felt, are a groove in the center bearing. Proper tension between the plates is maintained by a stabilizing spring and washer assembly on a post extending from the lower stationary plate up through the support plate (Fig. 60). The movable plate is stabilized in operation by the three support bearings, which are placed so as to offset opposing thrusts of the breaker lever arm spring and the stabilizing spring. The stabilizing spring prevents tilting of the movable plate which might otherwise result from the pressure of the rubbing block on the cam. Sidewise motion of the upper plate while the distributor is operating is prevented by the combined action of the side spring and the breaker lever arm spring. The springloaded construction of the breaker plate automatically takes up looseness created by normal wear, and prevents any tendency to chatter.
The vacuum control unit is mounted on the outside of the distributor housing and is linked mechanically to the movable breaker plate.
Advance
To get the best performance and economy from the engine at all speeds and under all load conditions it is necessary to change the ignition timing with variations in speed and load conditions. This is done automatically by two methods.
With the engine at idling speed, the spark will occur according to the timing setting. As the engine speed increases the centrifugal weights in the distributor (Fig. 61) start to swing outward advancing the spark. This continues until the engine reaches a speed at which maximum advance is obtained (see Specifications). As engine speed decreases the springs pull the weights inward, retarding the spark and providing governor advance in direct relation to engine speed.
A vacuum spark advance mechanism is provided to improve performance and economy on engines operating under part-throttle conditions by supplying additional spark advance at times when a high vacuum exists in the engine manifold. This mechanism which is connected to the distributor, has a diaphragm chamber connected to the carburetor so that manifold vacuum causes the vacuum spark control diaphragm to compress the spring and advance the spark by rotating the distributor housing on the 6-cylinder engine and the distributor movable breaker plate on the 8-cylinder engine. This advances the spark to the maximum, but only with comparatively high manifold vacuum. Each time the throttle is opened wider for acceleration the manifold vacuum decreases retarding the spark to prevent excessive detonation. At high vehicle speed with nearly wide open throttle the vacuum is low; therefore the vacuum spark advance is not in operation. However, under this condition maximum centrifugal advance is in use.
The ignition coil (Fig. 62) is an oil-filled, hermetically-sealed unit designed specifically for use with an external resistor in the 12-volt system. The ignition coil transforms low voltage battery current to a high voltage current which will jump the gap at the spark plugs. The coil consists of a soft laminated core over which is placed high voltage (secondary) winding and low voltage (primary) winding. This assembly is carefully insulated and placed in a metal container, filled with transformer oil and hermetically sealed to prevent entrance of moisture. The external resistor, connected in series with the primary circuit between the battery and coil (Fig. 57), dissipates nearly half the heat which otherwise would be generated within the coil itself. The resistor is wound with wire which changes resistance only slightly with temperature. This characteristic prevents excessive primary current at low temperatures and thus reduces the tendency for the contact points to oxidize in cold weather.
To obtain greatly improved starting performance at low temperatures, the resistor is by-passed during cranking, thereby connecting the ignition coil directly to the battery. This makes full battery voltage available to the coil and thus keeps ignition voltage as high as possible during cranking. The by-passing of the resistor during cranking is accomplished within the ignition switch.
CAUTION: If the ignition switch is used to complete the circuit to the cranking motor while making underhood cranking tests, the distributor primary lead must be grounded to prevent engine firing.
The key-operated ignition-starting switch is located in the low tension circuit between the battery and the coil (ignition circuit) and between the battery and the starting motor (starting circuit). It is used to make or break the ignition primary circuit when starting or stopping the engine and to complete the circuit to activate the solenoid and starting motor for cranking. The ignition-starting switch incorporates a resistor by-pass feature which makes full battery voltage available to the coil during cranking instead of permitting the circuit to pass through the external resistor as is the case during normal operation of the engine.
The ignition-starting switch has four positions: LOCK, OFF, ON,
and START. To operate, turn switch to START. As soon as the engine
starts, release switch, which will return to ON position. The key is
required only when turning to or from LOCK position.
Spark Plugs
AC 44-5, 14 mm. spark plugs are provided as original equipment on all passenger car models. One plug is positioned in each combustion chamber to provide for the spark to ignite the combustion mixture. Additional plugs are provided for service use and are described under Spark Plugs-Servicing of Units Off the Vehicle.
The distributor and spark plugs are the only ignition system components that require periodic service. The remainder of the ignition system requires only periodic inspection to check operation of the units, tightness of the electrical connections, and condition of the wiring. Men checking the coil, test with a reputable tester.
Six Cylinder Engine
Every 1000 Miles
Tighten grease cup one full turn. Fill cup with lubricant when necessary.
Every 5000 Miles
Eight Cylinder Engine
Every 1000 Miles
Fill hinge cap oiler with light engine oil.
Every 5000 Miles
Wipe off any excess oil appearing on the breaker plate. Excess oil may get on the contact points and cause them to burn.
Spark plugs should be removed, inspected, cleaned and regapped every 5000 miles. Defective plugs should be replaced. See Servicing of Units Off the Vehicle.
For efficient operation the ignition must he properly timed. This operation is described under Tune-up in Section 6.
If the checks outlined under General Trouble Shooting indicate that the ignition system is at fault, the following checks may be made to help locate the difficulty. All checks are to be made with the lights and accessories off and in the sequence shown. Voltage readings referred to are indicated on Fig. 63. If the engine starts but immediately stops when the starting switch is released from the START position steps 1-4 may be omitted.
1. Operation - Check all connections in Primary and Secondary circuit 2. Operation- Remove all secondary coil lead from distributor cap. Hold 1/4 inch from engine while cranking, and observe if spark occurs. Specification - If spark occurs, check following..... Possible Trouble
3. Operation - Check Voltage V-1 while cranking Specification - 1 Volt Max. Possible Trouble
4. Operation - Check Voltage V-2 ignition switch "On," points open Specification - Normal Battery Voltage Possible Trouble
5. Operation - Check Voltage V-2 ignition switch "On," points closed Specification - 5 to 7 Volts. If over 7, check following... Possible Trouble
Specification - If under 5, check following... Possible Trouble
6. Operation - Check Voltage V-3 ignition switch "On," points closed Specification - 0.2 Volts Max. Possible Trouble
7. Operation - Check Voltage V-4 ignition switch "On," points closed Specification - 0.7 Volts Max. Possible Trouble
8. Operation - If these checks fail to find cause of trouble - remove distributor, coil, and resistor from engine and check to specifications. Also check wiring harness.
Distributor Contact Points
Distributor Condenser
Distributor - Six Cylinder Engine
Distributor - Eight Cylinder Engine
Coil and Resistor Replacement
Ignition Switch Replacement
Spark Plugs
Distributor Contact Points
Criteria for Replacing Points
Examine the distributor points. Dirty points should be cleaned with a clean point file. Normal point condition is an overall grey color. If a test instrument for checking resistance is available, check the point resistance. The criteria for point quality should be a combination of visual inspection and a resistance or voltage drop check. If the points are badly worn, pitted or misaligned, replacement is recommended. If, with the points closed and the ignition switch in the ON position, there is less than a 0.125 volt drop across the points, the points may be considered satisfactory for further use. This check may be made with a sensitive voltmeter or one of the various point resistance meters available for this purpose.
Abnormal Point Wear
Under normal operating conditions, distributor contact points will provide many thousands of miles of service. Points which have undergone several thousand miles of operation will have a rough surface, but this should not be interpreted as meaning that the points are worn out. If the roughness between the points matches so that a large contact area is maintained, the points will continue to provide satisfactory service until most of the tungsten is worn off.
However, if the points burn or pit, they will soon become unsatisfactory for further operation. Not only must they be replaced, but the ignition system and engine must be checked to determine the cause of the trouble so it can be eliminated. Unless the condition causing the point burning or pitting is corrected, the new points will provide no better service than the old points.
Burning of Points
Contact point burning will result from high voltage, presence of oil or other foreign material, defective condenser and improper point adjustment. High voltage causes an excessively high current flow through the contact points which burns them rapidly. High voltage can result from an improperly adjusted or inoperative voltage regulator.
Oil or crankcase vapors which work up into the distributor and deposit on the point surfaces will cause them to burn rapidly. This is easy to detect since the oil produces a smudgy line under the contact points. Clogged engine breather pipes permit crankcase pressure to force oil or vapors up into the distributor. Over-oiling the distributor will also produce the condition.
If the contact point opening is too small (cam angle too large), the points will be closed too large a part of the total operating time. Average current flow through the points will be too high so the points will burn rapidly and arcing will occur between the points resulting in low secondary voltage and engine miss.
High series resistance in the condenser circuit will prevent normal condenser action so the contact points will burn rapidly. This resistance may be caused by a loose condenser mounting or lead connection, or by poor connections inside the condenser. See Distributor Condenser in this section for a discussion of condenser testing.
Pitting of Points
Contact point pitting results from an out-of balance condition in the ignition system which causes transfer of tungsten from one point to the other so that a tip builds up on one point while a pit forms in the other (Fig. 64 and Fig. 65). The direction in which the tungsten transfers can be used as a basis for analysis and correction of pitting. For instance, if the material transfers from the negative to the positive point (Fig. 64), one or more of these corrections may be made: increase condenser capacity; shorten condenser lead; separate distributor-to-coil low- and high-tension leads; move these leads closer to ground.
If the material transfers from the positive to the negative point (Fig. 65), reduce condenser capacity, move distributor-to-coil leads closer together, move these leads away from ground, or lengthen condenser lead.
Cleaning of Points
Dirty contact points should be dressed with a few strokes of a clean, fine-cut contact file. The file should not be used on other metals and should not be allowed to become greasy or dirty. Never use emery cloth to clean contact points. Contact surfaces, after considerable use, may not appear bright and smooth, but this is not necessarily an indication that they are not functioning satisfactorily. Do not attempt to remove all roughness nor dress the point surfaces down smooth; merely remove scale or dirt.
Badly burned or pitted contact points should be replaced and the cause of trouble determined so it can be eliminated. High resistance or loose connections in the condenser circuit, oil or foreign materials on the contact surfaces, improper point adjustment or high voltages may cause oxidized contact points. Check for these conditions where burned contacts are experienced. An out-of balance condition in the ignition system, often the result of too much or too little condenser capacity, is indicated where point pitting is encountered.
Setting and Alignment of Points
The point opening of new points can be checked with a feeler gauge, but the use of a feeler gauge on rough or uncleaned used points is not recommended since accurate gauging cannot be done on such points. The gauge measures between high spots on the points instead of the true point opening (Fig. 66).
Contact points must be set to the proper opening. Points set too close may tend to bum and pit rapidly. Points with excessive separation tend to cause a weak spark at high speed. Proper point settings for all models are:
.019" new points
.016" used points
New points must be set to the larger opening as the rubbing block will wear down slightly while seating to the cam. Contact points should be cleaned before adjusting if they have been in service.
To adjust contact point opening:
NOTE: Cam angle readings taken at speeds above 1750 engine RPM may prove unreliable on some cam angle meters.
Contact Point Pressure
The contact point pressure must fall within specified limits. Weak tension will cause chatter resulting in arcing and burning of the points and an ignition miss at high speed, while excessive tension will cause undue wear of the contact points, cam and rubbing block. Breaker arm spring tension should be 19-23 ounces. The contact point pressure should be checked with a spring gauge. The scale should be hooked to the breaker lever and the pull exerted at 90 degrees to the breaker lever as shown in Fig. 68. The reading should be taken just as the points separate. The pressure can be adjusted by bending the breaker lever spring. If the pressure is excessive, it can be decreased by pinching the spring carefully (Fig. 69). To increase pressure, the lever must be removed from the distributor so the spring can be bent away from the lever. Avoid excessive spring distortion.
NOTE: For ease in adjustment of spring tension on new points, the breaker lever as received will produce a tension exceeding specifications.
Six Cylinder Distributor
Contact Point Replacement-
Eight Cylinder Distributor
Performance
The following four factors affect condenser performance and each factor must be considered in making any condenser test.
Low Insulation Resistance (Leakage) prevents condenser from holding a charge. All condensers are subject to leakage which up to a certain limit is not objectionable
High Series Resistance excessive resistance in the condenser circuit due to broken strands in condenser lead or to defective connections. This will cause burned points and ignition failure upon initial start and at high speeds.
Capacity determined by the area of the metallic elements and the insulating and impregnating materials.
For a complete check of the condenser, use a tester which will check for the above conditions.
Follow the instructions given by the manufacturer of the test equipment. Condenser capacity should be .18-.23 microfarad.
Six Cylinder Distributor
Condenser Replacement
Eight Cylinder Distributor
Removal
Disassembly
Before disassembling distributor it is advisable to place the distributor in a distributor testing machine or synchroscope and, after adjusting point gap, test distributor for variation of spark, correct centrifugal and vacuum advance (see
Specifications). This test will give valuable information on distributor condition and indicate parts replacement which may be necessary. Check area on breaker plate just beneath breaker points. A smudgy line indicates that oil or crankcase vapors have been present between points.
Cleaning and Inspection
Assembly
Installation-Engine
