electrical CHEVROLET CAMARO 1967 1.G Chassis Service Manual

ENGINE-ELECTRICAL 6Y-20

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.

REPLACEMENT

Four and Six Cylinder Engine Distributor

1.
Release distributor cap hold-down screws, remove

cap and place it out of work area.

2.
Remove rotor.

3.
Pull primary and condenser lead wires from contact

point quick disconnect terminal (fig. 4i).

4.
Remove contact set attaching screw, lift contact point

set from breaker plate.

5.
Clean breaker plate of oil smudge and dirt.

6. Place new contact point assembly in position on

breaker plate, install attaching screw.

CAUTION: Carefully wipe protective film from

point set prior to installation.

NOTE: Pilot on contact set must engage match-

ing hole in breaker plate.

7.
Connect primary and condenser lead wires to quick

disconnect terminal on contact point set. .

8. Check and adjust points for proper alignment and

breaker arm spring tension (fig. 5i). Use an aligning

tool to bend stationary contact support if points need

alignment.

NOTE: The contact point pressure must fall

within specified limits. Weak tension will cause

CONTACT SET

ATTACHING

SCREW

QUICK

DISCONNECT

TERMINAL

BREAKER PLATE

ATTACHING SCREWS
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 Figure 5i. The

reading should be taken just as the points sepa-

rate.
The pressure can be adjusted by bending

the breaker lever spring. If the pressure is ex-

cessive, it can be decreased by pinching the

spring carefully. 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.

9. Set point opening (.019" for new points).

10.
Reinstall rotor, position and lock distributor cap to

housing.

11.
$tart engine and test dwell and ignition timing.

Eight Cylinder Engine Distributor

1.
The contact point set is replaced as one complete

assembly and only dwell angle requires adjustment

after replacement. Breaker lever spring tension and

point alignment are factory set.

2.
Remove the distributor cap by placing a screw driver

in the slot head of the latch, press down and turn 1/4

turn in either direction.

3.
Remove the two attaching screws which hold the base

of the contact set assembly in place.

4.
Remove the primary and condenser leads from their

nylon insulated connection (fig. 6i) in contact set.

5.
Reverse Steps 2, 3 and 4 to install new contact set.

CAUTION:. Install the primary and condenser

leads as shown in Figure 6i. Improper installa-

tion will cause lead interference between the

cap,
weight base and breaker advance plate.

6. If car has 20,000 to 25^000 miles (or sooner if

desired) the cam lubricator wick (fig. 7i) should be

changed. Using long nosed pliers squeeze assembly

together at base and lift out. Remove all old lubri-

cant from cam surface. Replace in same manner.

Fig.
4i—Breaker Plate and Attaching Parts
Fig. 5i—-Checking Breaker Arm Spring Tension

CHEVROLET CHASSIS SERVICE MANUAL

ENGINE-ELECTRICAL
6Y-21

Fig.
6i—Distributor Lead Arrangements

NOTE:
End of cam
lubricant wick should
be

adjusted
to
just touch
cam
lobes. Over lubrica-

tion
of cam
resulting
in
grease
on
contact points

can-
be
caused
by cam
lubrication wick bearing

too hard against
cam
surface.
A
correctly
ad-

justed
cam
lubricator wick will provide adequate

lubrication
for cam. Do not
apply additional

grease
to cam
surface.

7.
Start engine
and
check point dwell
and
ignition

timing.
ACTUAL
POINT OPENING
.021

.016
FEELER GAUGE

LOCATOR ___JH^H

(ROUND)
V~^3H|

CENTRIFUGAL
\
jdft

ADVANCE
-~-»JBlMBl

MECHANISM
«H

CAM g^k. / X

LUBRICATOR
V^^^

REPLACEMENT
^£9

^-ADJUST
SQUARELY

AND
JUST

TOUCHING
LOBE

OF
CAM
.ROTOR

I^^I^BL
LOCATOR

(PBV 7
(SQUARE)

SBSSF
/

WWjga^/
^/
LUBRICATOR

H^f
CAUTION!

S5y
NEVER
OIL

•-^
CAM
LUBRICATOR-

REPLACE
WICK

WHEN
NECESSARY
Fig.
8i—Inaccurate Gauging
of
Rough Points

SETTING DWELL ANGLE

Four
and Six
Cylinder Engine Distributors

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

mechanical gauging cannot
be
done
on
such points (fig. 8i).

Contact points must
be set to the
proper opening.

Points
set too
close
may
tend
to
burn and
pit
rapidly.

Points with excessive separation tend
to
cause
a
weak

spark
at
high speed. Proper point setting
for all

models
are:

.019"
for new
points

.016"
for
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.

LATERAL

MISALIGNMENT
PROPER

LATERAL
ALIGNMENT

pCORRECT
LATERAL MISALIGNMENT
BY

M
BENDING FIXED CONTACT SUPPORT

[NEVER
BEND BREAKER LEVER

Fig.
7i—Top View
of
Distributor

Fig.
9i—Alignment
of
Points

CHEVROLET
CHASSIS SERVICE /MANUAL

ENGINE-ELECTRICAL 6Y-22

ADJUST DWELL

ANGLE SETTING OR

POINT OPENING

Fig.
lOi—Settihg Point Opening

To adjust the contact point opening:

1.
If necessary, align points (fig. 9i) by bending the

fixed contact support. Do not bend the breaker lever.

Do not attempt to align used points; replace them

where serious misalignment is observed. Use an

aligning tool if available.

2.
Turn or crank the distributor shaft until the breaker

arm rubbing block is on the high point of the cam

lobe.
This will provide maximum point opening.

3.
Loosen the contact support lock screw.

4.
Use a screw driver (fig. lOi) to move the point sup-

port to obtain a .019" opening for new points and a

.016"
opening for used points.

5.
Tighten the contact support lock screw and recheck

the point opening.

6. After checking and adjusting the contact point open-

ing to specifications, the cam angle or dwell should

be checked with a dwell angle meter if such equip-

ment is available (see Specifications for proper dwell

angle).
If the cam angle is less than the specified

minimum, check for defective or misaligned contact

points or worn distributor cam lobes. The variation

in cam angle readings between idle speed and 1750

engine rpm should not exceed 3°. Excessive varia-

tion in this speed range indicates wear- in the

distributor.

NOTE:
Cam angle readings taken at speeds

above 1750 engine rpm may prove unreliable

on some cam angle meters.

Eight Cylinder Engine Distributor

On the Vehicle

With the engine running at idle and operating tempera-

tures normalized, the dwell is adjusted by first raising

the window provided in the cap and inserting a "Hex"

type wrench into the adjusting screw head (fig. Hi).
WINDOW

r- "HEX" TYPE

WRENCH

ADJUSTING

SCREW

Fig.
-lli—Adjusting Dwell Angle

1.

Preferred Method - Turn the adjusting screw until

the specified dwell angle is obtained as measured in

degrees (28° to 32°, 30° preferred) by a dwell angle

meter.

2.
Alternate Method - Turn adjusting screw in (clock-

wise) until the engine begins to misfire, then turn

screw 1/2 turn in the opposite direction (counter-

clockwise). This will give the approximate dwell

angle required. (Use only when meter is not

available.)

Off the Vehicle

1.
Distributor Test Method:

a. With the distributor mounted on a distributor

testing machine, connect the dwell meter to the

distributor primary lead.

b.
Turn the adjusting screw (fig. lli) to set the dwell

angle to 30 degrees.

2.
Test Light Method:

a. With the distributor mounted in a vise, connect a

testing lamp to the primary lead.

b.
Rotate the shaft until one of the circuit breaker

cam lobes is under the center of the rubbing block

of the breaker lever.

c. Turn the adjusting screw clockwise (fig. lli) until

the lamp lights, then give the wrench 1/2 turn in

the opposite direction (counter-clockwise) to ob-

tain the proper dwell angle.

DISTRIBUTOR CONDENSER

PERFORMANCE DIAGNOSIS

The following four factors affect condenser perform-

ance,
and each factor must be considered in making any

condenser test.

1.
Breakdown - A failure of the insulating material. A

direct short between the metallic elements of the

condenser. This prevents any' condenser action.

2.
Low Insulating Resistance (Leakage) - Low insula-

tion resistance prevents the condenser from holding

a charge. All condensers are subject to leakage

which, up to a certain limit, is not objectionable.

3.
High Series Resistance - Excessive resistance in

the condenser circuit due to broken strands in the

CHEVROLET CHASSIS SERVICE MANUAL

ENGINE-ELECTRICAL 6Y-23

condenser leak or to a defective connection. This

will cause burned points and ignition failure upon

initial starts and at high speeds.

4.
Capacity - Capacity is determined by the area of

the metallic elements and the insulating and im-

pregnating materials.

For a complete check of the condenser, use a tester

which will check for all of the above conditions. Follow

the instructions given by the manufacturer of the

test equipment. Condenser capacity should be
.18-:
23

microfarads.

REPLACEMENT

Four and Six Cylinder Engine Distributor (Fig. 4i)

1.
Release distributor cap hold-down screws, remove

cap and place it out of the work area.

2.
Remove rotor.

3.
Disconnect condenser lead wire from contact point

quick-disconnect terminal.

4.
Remove condenser attaching screw, lift.condenser

from breaker plate and wipe breaker plate clean.

5. Install new condenser using reverse of procedure

outlined above.

Eight Cylinder Engine Distributor

1.
Remove distributor cap.

2.
Loosen condenser lead attaching screw (fig. 6i) and

lift out condenser lead clip.

3.
Remove screw holding condenser bracket to breaker

plate and slide condenser from bracket.

4.
To replace condenser reverse the above procedure.

NOTE:
Make sure that new condenser lead is

installed in proper position (fig. 6i).

DISTRIBUTOR

(BREAKER POINT TYPE)

REMOVAL

1.
On radio equipped Corvettes, remove ignition shield

from over distributor and coil. One bolt is accessible

from top of shield, the other two are at rear of

shield, facing firewall.

2.
Release the distributor cap hold-down screws, re-

move the cap and place it clear of the work area.

NOTE:
If necessary, remove secondary leads

from the distributor cap after first marking the

cap tower for the lead to No. 1 cylinder. This

will aid in the reinstallation of leads in the cap.

3.
Disconnect the distributor primary lead from the coil

terminal.

4.
Scribe a realignment mark on the distributor bowl

and engine in line with the rotor segment.

5. Disconnect vacuum line to distributor and tachometer

drive cable (Corvette). Remove the distributor hold-

down bolt and elamp and remove the distributor from

the engine. Note position of vacuum advance mecha-

nism relative to the engine.

CAUTION: Avoid rotating the engine with the

distributor removed as the ignition timing will

be upset.
Rg.
121-L-6 Distributor-Exploded View

1.
Breaker Plate Attaching

Screws

2.
Condenser Attaching

Screws

3. Condenser

4.
Breaker Plate Assembly

4a.
Cam Lubricator

5. Vacuum Control Assembly

6. Vacuum Control

Attaching Screws

7. Housing

8. Cap

9. Rotor

DISASSEMBLY
10.
Contact Point

Attaching Screw

11.
Contact Point Assembly

12.
Weight Cover

Attaching Screws

13.
Weight Cover

14.
Weight Springs

15.
Advance Weights

16. Cam Assembly

17.
Main Shaft Assembly

18.
Roll Pin

19.
Drive Gear

It is advisable to place the distributor in a distributor

testing machine or synchroscope prior to disassembly.

CHEVROLET CU
SERVICE MANUAL

ENGINE-ELECTRICAL 6Y-24

Fig.
13I-V-8 Distributor (Typical)-Exploded View

1.

2.

2a.

3.

4.
Condenser

Contact Point Assembly

Cam Lubricator

Retaining Ring

Breaker Plate
5.

5a.

6.

7.
Felt Washer

Plastic Seal

Vacuum Advance

Unit

Housing
8.^
Shim
Washer

9. Drive Gear Pin

10.
Drive Gear

11.
Cap

12.
Rotor
13.
Weight Springs

14.
Mainshaft

15.
Advance Weights

16.
Cam Weight

Base Assembly

When mounting distributors for tests, first secure the

gear in the test drive mechanism, then push the distribu-

tor housing downward toward the gear to take up any end

play between the gear and the housing.

NOTE:
When testing distributors that have

their lower shaft support bushing located in the

engine block (6 cylinder engines), a special

adapter should be used to insure the shaft will

run true in its housing.

Test the distributor for variation of spark, correct

centrifugal and vacuum advance and condition of contacts.

This test will give valuable information on distributor

condition and indicate parts replacement which may be

necessary. Check the area on the breaker plate just

beneath the contact points. A smudgy line indicates that

oil or crankcase vapors have been present between the

points.

Four and Six Cylinder Engines

Refer to Figure 12i.

1.
Remove the rotor.
2.

3.
Remove the vacuum control assembly retaining

screws, detach the unit from the distributor housing.

Disconnect the primary and condenser leads from the

contact point quick disconnect terminal, remove the

contact point set attaching screw, condenser attach-

ing screw. Remove the point set and condenser from

the breaker plate.

Remove the breaker plate attaching screws, remove

the breaker plate from the distributor housing (fig.

NOTE:
Do not disassemble breaker plate any

further.

5. Remove the roll pin retaining the driven gear to the

mainshaft, slide the gear from the shaft.

6. Slide the cam and mainshaft from the distributor

housing.

7. Remove the weight cover, and stop plate screws, re-

move the cover, weight springs, weights and slide

cam assembly from the mainshaft.

V-8 Engines

Refer to Figure 13i.

CHEVROLET CHASStS SERVICE MANUAL

ENGINE-ELECTRICAL 6Y-25

1.
Remove the rotor.

2.
Remove both weight springs and advance weights.

3.
Remove roll pin retaining driven gear to distributor

shaft, slide the gear and spacers from the shaft.

Remove tachometer drive gear on Corvette models.

4.
Before sliding the distributor shaft from the hous-

ing, check for and remove any burrs on the shaft.

This will prevent damage to the seals and bushing

still positioned in the housing.

5. Slide the distributor mainshaft and cam-weight base

assembly from the housing.

6. Remove vacuum advance mechanism retaining

screws, remove the vacuum advance assembly.

7. Remove the spring retainer, remove the breaker

plate assembly from the distributor housing. Re-

move the contact point and condenser from the

breaker plate. Remove the felt washer and plastic

seal located beneath the breaker plate.

CLEANING AND INSPECTION

1.
Wash all parts in cleaning solvent except cap, rotor,

condenser, breaker plate assembly and vacuum con-

trol unit. Degreasing compounds may damage insula-

tion of these parts or saturate the lubricating felt in

the case of the breaker plate assembly.

2.
Inspect the breaker plate assembly for damage or

wear and replace if necessary.

3.
Inspect the shaft for wear and check its fit in the

bushings in the distributor body. If the shaft or bush-

ings are worn, the parts should be replaced.

4.
Mount the shaft in "V" blocks and check the shaft

alignment with a dial guage. The run-out should not

exceed .002".

5. Inspect the advance weights for wear or burrs and

free fit on their pivot pins.

6. Inspect the cam for wear or roughness. Then check

its fit on the end of the shaft. It should be absolutely

free without any roughness.

7. Inspect
the •
condition of the distributor points. Dirty

points should be cleaned and badly pitted points

should be replaced. (See Distributor Contact Points.)

8. Test the condenser for series resistance, micro-

farad capacity (.18 to .23) and leakage or breakdown,

following the instructions given by the manufacturer

of the test equipment used.

9. Inspect the distributor cap and sparkplug wires for

damage and replace if necessary.

ASSEMBLY

Four and Six Cylinder Engine

Refer to Figure 12i for Exploded View of Distributor.

1.
Replace cam assembly to mainshaft.

NOTE:
Lubricate top end of shaft with Delco

cam and ball bearing grease or equivalent prior

to replacing.

2.
Install governor weights on their pivot pins, replace

weight springs. Install weight cover and stop plate.

3.
Lubricate mainshaft and install it in distributor

housing.

4.
Install distributor driven gear to mainshaft and in-

sert attaching roll pin. Check to see that shaft turns

freely.
5. Install breaker plate assembly in the distributor body

and attach retaining screws.

6. Attach condenser and contact point set in proper lo-

cation with appropriate attaching screws.

NOTE:
Contact point set pilot must engage

matching hole in breaker plate. Connect primary

and condenser leads to contact set quick-

disconnect terminal.

7. Attach vacuum control assembly to distributor

housing.

8. Check and adjust contact point opening and align-

ment (See setting and alignment of points.)

9. Check breaker lever spring tension which should

be.
19-23 ounces. (See contact point replacement.)

V-8 Assembly-(Fig. 13i)

1.
Fill housing lubricating cavity with proper compound,

press in new plastic seal and install felt washer.

2.
Replace the vacuum advance unit, install the breaker

plate in housing and install the spring retainer on

the upper bushing.

3.
Lubricate and slide weight cam over mainshaft and

install weights and spring (fig. 14i).

4.
Insert mainshaft into housing, indexing it with drive

gear and washers. Install tachometer drive gear on

Corvette models.

5. Slide distributor drive gear shims and gear over

shaft and install new pin. Tap new pin through gear

and mainshaft. Check shaft for free rotation.

NOTE:
Mainshaft end clearance should be

.002"-.007". Add or remove shims as necessary.

6. Install contact point set and condenser to breaker

plate. Connect leads as shown in Figure 6i.

NOTE:
Contact point spring tension is factory-

set above specifications to assure ease of final

adjustment. Correct tension is 19-23 oz.

7. Install rotor to cam assembly, indexing round and

square pilot holes.

Flg.
Hi-Advance Weights Installed

CHEVROLET CHASSIS SERVICE

ENGINE-ELECTRICAL 6Y-26

INSTALLATION-ENGINE NOT DISTURBED

(ALL MODELS)

1.
Turn the rotor about 1/8 turn in a clockwise direc-

tion past the mark previously placed on the distribu-

tor housing to locate rotor.

2.
Push the distributor down into position in the block

with the housing in a normal "installed" position

(fig. 15i).

NOTE: It may be necessary to move rotor

slightly to start gear into mesh with camshaft

gear, but rotor should line up with the mark

when distributor is down in place.

3.
Tighten the distributor clamp bolt snugly and con-

nect vacuum line. Connect primary wire to coil

terminal and install cap. Also install spark plug and

high tension wires if removed.

NOTE: It is important that the spark plug wires

be installed in their proper location in the

supports.

4.
Time ignition as previously described under Tune-

Up in Section 6.

INSTALLATION-ENGINE DISTURBED

(ALL MODELS)

1.
Locate No. 1 piston in firing position by either of two

methods described below,

a. Remove No. 1 spark plug and, with finger on plug

hole,
crank engine until compression is felt in the

No.
1 cylinder. Continue cranking until timing

mark on crankshaft pulley lines up with timing

tab attached to engine front cover.

b.
Remove rocker cover (left bank on V-8 engines)

and crank engine until No. 1 intake valve closes

and continue to crank slowly about 1/3 turn until
CENTRIFUGAL

jS ADVANCE

ROTATING

POLE PIECE

STATIONARY

POLE PIECE

MAGNETIC

PICKUP

ASSEMBLY

VACUUM

ADVANCE

DISTRIBUTOR

HOUSING

Fig.
151—Six Cylinder Engine Distributor
Fig.
16i—Magnetic Pulse Distributor Components

CHEVROLET CHASSIS SERVICE MANUAL

ENGINE-ELECTRICAL 6Y-27

timing mark on pulley lines up with timing tab.

2.
Position distributor to opening in block in normal

installed attitude (fig. 15i), noting position of vacuum

control unit.

3.
Position rotor to point toward front of engine (with

distributor housing held in installed attitude), then

turn rotor counter-clockwise approximately 1/8 turn

more toward left cylinder bank and push distributor

down to engine camshaft. It may be necessary to ro-

tate rotor slightly until camshaft engagement is felt.

4.
While pressing firmly down on distributor housing,

kick starter over a few times to make sure oil pump

shaft is engaged. Install hold-down clamp and bolt

and snug up bolt.

5. Turn distributor body slightly until points just open

and tighten distributor clamp bolt.

6. Place distributor cap in position and check to see

that rotor lines up with terminal for No. 1 spark

plug.

7. Install cap, check all high tension wire connections

and connect spark plug wires if they have been re-

moved. It is important that the wires be installed in

their location in the supports.

NOTE:
The brackets are numbered to show the

correct installation. Wires must be installed as

indicated to prevent cross firing.

8. Connect vacuum line to distributor and distributor

primary wire to coil terminal.

9. Start engine and set timing as described under Turn-

Up in Section 6.

BREAKERLESS (MAGNETIC PULSE)

DISTRIBUTOR

REMOVAL (CORVETTE)

1.
If vehicle is equipped with radio, remove three bolts

securing ignition shield over distributor and coil.

One bolt is accessible from the top of shield, the

other two are at rear of shield, facing firewall.

2.
Disconnect tachometer drive cables from distributor

housing.

3.
Disconnect pickup coil leads at connector.

4.
Remove distributor cap.

5. Crank engine so rotor is in position to fire No. 1

cylinder and timing mark on harmonic balancer is

indexed with pointer.

6. Remove vacuum line from distributor.

7. Remove distributor clamping screw and hold-down

clamp.

8. Remove distributor and distributor-to-block gasket.

It will be noted that the rotor will rotate as the

distributor is pulled out of the block. Mark the re-

lationship of the rotor and the distributor housing

after removal so that the rotor can be set in the

same position when the distributor is being installed.

DISASSEMBLY (Fig. 16i)

NOTE:
If a distributor is being disassembled

for replacement of the stationary magnetic

pickup assembly only, it will be necessary to

perform only Steps 3, 4, 5, 7, 8, 9, and 12 of the

service procedure listed below.
1.
Remove screws securing rotor and remove rotor.

2.
Remove centrifugal weight springs and weights.

3.
Remove the tachometer drive gear from the distribu-

tor (Corvette only).

4.
Remove roll pin, then remove distributor drive gear

and washer.

CAUTION: To prevent

magnet, support drive gear
;e to the permanent

?n
driving out roll

pin.

5. Remove drive shaft assembly.

6. Remove centrifugal weight support and timer core

from drive shaft.

7. Remove connector from pickup coil leads.

8. Remove retaining ring which secures magnetic

core support plate to distributor shaft bushing in

housing.

9. As a unit, remove the entire magnetic pickup assem-

bly from the distributor housing.

10.
Remove brass washer and felt pad.

11.
Remove vacuum advance unit.

12.
To reassemble distributor, perform the above steps

in reverse order.

INSTALLATION (CORVETTE)

1.
Check to see that the engine is at firing position for

No.
1 cylinder (timing mark on harmonic balancer

indexed with pointer).

2.
Position a new distributor-to-block gasket on the

block.

3.
Before installing distributor, index rotor with hous-

ing as noted when distributor was removed. Install

distributor in block so that vacuum diaphragm faces

approximately 45° forward on the right side of the

engine and the rotor points toward contact in cap for

No.
1 cylinder.

4.
Replace distributor clamp leaving screw loose

enough to allow distributor to be turned for timing

adjustment.

5. Install spark plug wires in distributor cap. Place

wire for No. 1 cylinder in tower (marked on old cap

during disassembly) then install remaining wires

clockwise around the cap according to the firing

order (1-8-4-3-6-5-7-2).

6. Attach distributor to coil primary wires.

7. Replace distributor cap.

8. Adjust timing and then fully tighten distributor clamp

screw.

9. Attach vacuum line to distributor.

10.
Connect tachometer drive cables to distributor body.

11.
Replace ignition shields.

DISTRIBUTOR OFF-ENGINE TEST

The distributor's centrifugal and vacuum advance can

be checked in a distributor testing machine or synchro-

scope specially adapted or designed to accommodate this

type distributor. However, since this involves removing

the distributor from the engine, this test may be post-

poned until other system checks have been made. A dwell

reading cannot be obtained on this distributor and it is not

likely that the centrifugal or vacuum advance will be a

cause of trouble.

COIL REPLACEMENT

1.
Disconnect ignition switch and distributor leads from

CHEVROLET CHASSIS SERVICE MANUAL

ENGINE-ELECTRICAL 6Y-28

terminals on eoil. On Corvettes equipped with radio,

remove bolts securing ignition shield over distribu-

tor and coil.

2.
Pull high tension wire from center terminal of coil.

3.
Remove the two coil support mounting bolts or loosen

friction clamp screw and remove coil.

4.
Place new coil in position and install attaching bolts

or tighten clamp screw.

5.
Place high tension lead securely in center terminal

of coil and connect ignition switch and distributor

primary leads to terminals on coil. Replace ignition

shield on Corvettes.

6. Start engine and test coil operation.

IGNITION PULSE AMPLIFIER

DISASSEMBLY

To check the amplifier for defective components, pro-

ceed as follows:

1.
Remove the bottom plate from the amplifier.

2.
To aid in reassembly, note the locations of the lead

connections to the panel board.

3.
Remove the three panel board attaching screws, and

lift the assembly from the housing.

4.
To aid in reassembly, note any identifying markings

on the two transistors and their respective locations

on the panel board and heat sink assembly.

5.
Note the insulators between the transistors.and the

heat sink, and the insulators separating the heat sink

from the panel board.

6. Remove the transistor attaching screws, and sepa-

rate the two transistors and heat sink from the panel

board.

7.
Carefully examine the panel board for evidence of

damage.

MOUNTING

SCREW

RESISTOR R5 jgSfe. / DIODE Dl

TRANSISTOR TR2

(UNDERNEATH)

1H L >©V

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SCREW I RESISTOR R6 CAPACITOR C2

TRANSISTOR TR3
COMPONENT CHECKS (Figs. \7\ and 18i)

With the two transistors separated from the assembly,

an ohmmeter may be used to check the transistors and

components on the panel board for defects. An ohmmeter

having a 1-1/2 volt cell, which is the type usually found

in service stations, is recommended. The low range

scale on the ohmmeter should be used except where

specified otherwise.

A 25 watt soldering gun is recommended, and a 60% tin

40%
lead solder should be used when re-soldering. Avoid

excessive heat which may damage the panel board. Chip

away any epoxy involved, and apply new epoxy which is

commercially available.

In order to check the panel board assembly, it is

necessary to unsolder at the locations indicated in Fig-

ure 18i the two capacitors C2 and C3. In all of the fol-

lowing checks, connect the ohmmeter as shown and then

reverse the ohmmeter leads to obtain two readings. The

amplifier circuitry is shown in Figure 19i.

1.
Transistors TR1 and TR2: Check each transistor by

referring to Figure 20i. If both readings in Step 1

are zero, the transistor is shorted. If both readings

in Step 2 are zero, the transistor is shorted; and if

both readings are infinite, the transistor is open.

Interpret Step 3 the same as Step 2.

2.
Trigger Transistor TR3:
11
both readings in Step 1

are zero, the transistor is shorted. If both readings

in Step 2 are zero, the transistor is shorted; and if

both readings are infinite, the transistor is open.

Interpret Step 3 the same as Step 2.

3.
Diode Dl: 11 both readings are zero, the diode is

shorted; and if both readings are infinite, the diode

is open.

4.
Capacitor Cl: If both readings are zero, the capaci-

tor is shorted.

5.
Capacitors C2 and C3: Connect the ohmmeter across

CHECKING

RESISTOR Rl

UNSOLDER
I
CHECKING TRIGGER

TRANSISTOR TR3
CHECKING

CAPACITOR C

Fig.
171—Pulse Amplifier Panel Board
Fig.
18i—Pulse
Amplifier
Component
Checks

CHEVROLET CHASSIS SERVICE MANUAL

ENGINE-ELECTRICAL 6Y-29

each capacitor (not illustrated). The capacitor is

shorted if both readings are zero.

6. Resistor Rl: The resistor is open if both readings

are infinite.

7. Resistor R2: Use an ohmmeter scale on which the

1800 ohm value is within, or nearly within, the

middle third of the scale. If both readings are infi-

nite, the resistor is open.

8. Resistor R3: Use an ohmmeter scale on which the

680 Ohm value is within, or nearly within, the middle

third of the scale. If both readings are infinite, the

resistor is open.

9. Resistor R4: Select an ohmmeter scale on which the

15000 ohm value is within, or nearly .within, the

middle third of the scale. If either reading is infi-

nite, the resistor is open. ~

10.
Resistor R5: Use the lowest range ohmmeter scale.

The resistor is open if either reading is infinite.

NOTE:
This resistor on some applications may

be located in the vehicle wiring harness, and not

on the panel board.

11.
Resistor R6: An ohmmeter scale on which the 150

ohm value is within or nearly within, the middle

third of the scale should be used. If both readings

are infinite, the resistor is open.

REASSEMBLY

During assembly, coat with silicone grease both sides

of the flat insulators used between the transistors and

heat sink, and also the heat sink on the side on which the

transistors are mounted. The silicone grease, which is

available commercially, conducts heat and thereby pro-

vides better cooling.'

IGNITION PULSE AMPLIFIER

R-5

C-3 Ju

MAGNETIC PULSE

DISTRIBUTOR
IGNITION SWITCH REPLACEMENT (Figs.
21
i to 23i)

CHEVROLET, CHEVY II AND CORVETTE

1.
Raise hood and disconnect battery ground cable from

battery.

2.
Remove lock cylinder by positioning switch in "off"

position and inserting wire in small hole in cylinder

face. Push in on wire to depress plunger and con-

tinue to turn key counter-clockwise until lock cylin-

der can be removed.

3.
Remove the metal ignition switch nut from the pas-

senger side of the dash using Tool J-7607 (Fig. 21i).

4.
Pull the ignition switch out from under the dash and

remove the wiring connectors.

5. To remove the "theft resistant" connector, the

switch must be out from under the dash as outlined

in Step 4. Using a screw driver unsnap the locking

tangs on the connector from their position on the

switch as shown in Figure 22i. Unplug the connector.

6. Snap the connector into place on a new ignition

switch.

7. Place the switch into position from behind the dash

and install the metal ignition switch nut.

8. Install the lock cylinder.

9. Install the battery cable to the battery and lower the

hood.

CHEVELLE

1.
Disconnect battery ground cable.

2.
Remove ash tray, retainer attaching screws and

retainer.

3.
Remove A/C distributor duct retaining screws and

duct.

Fig.
19i—Pulse Amplifier Internal Circuitry
Fig.
20i—Transistor Checking

CHEVROLET Oi