turn CHEVROLET CAMARO 1967 1.G Chassis Manual Online

SECTION 6M

ENGINE FUEL

CONTENTS OF THIS SECTION

Page

Carburetors 6M-1 Fuel Pumps .

Air Cleaners 6M-7 Special Tools
Page

6M-10

6M-12

CARBURETORS

INDEX

Page

General Description 6M-1

Service Procedures 6M-1

Preliminary Checks 6M-1

Idle Speed and Mixture Adjustment ........... 6M-1

Fast Idle Adjustment .................. 6M-3

Choke Adjustment 6M-3

Float Adjustment 6M-4
Page

Additional Adjustments 6M-4

Removal 6M-4

Test Before Installation 6M-5

Installation 6M-5

Fuel Filter Maintenance 6M-5

Choke Coil Replacement 6M-5

Throttle Linkage Adjustment . . 6M-6

GENERAL DESCRIPTION

Various carburetors (fig. lc) are used with Chevrolet,

Chevelle, Chevy II, Camaro and Corvette passenger

vehicles. These carburetors are designed to meet the

particular requirements of engines, transmissions and

vehicles, therefore carburetors that look alike are not

always interchangeable. (Refer to carburetor part num-

ber and/or specifications.)

Because many service procedures for the various

carburetors are similar, typical illustrations and pro-

cedures are used except where specific illustrations or
procedures are necessary to clarify the operation.

This section covers removal, installation and adjust-

ments (on engine) of carburetors. Also covered in this

section are maintenance procedures for choke coils,

throttle linkage and fuel filters. For carburetor .over-

haul procedures and additional adjustments (bench), re-

fer to Section 6M of the Overhaul Manual under the

carburetor being serviced.

Specifications for carburetors are located in the back

of this manual.

SERVICE PROCEDURES

Preliminary Checks

1.
Thoroughly warm-up engine. If the engine is cold,

allow to run for at least 15 minutes.

2.
Inspect torque of carburetor to intake manifold bolts

and intake manifold to cylinder head bolts to exclude

the possibility of air leaks.

3.
Inspect manifold heat control valve (if used) for free-

dom of action and correct spring tension.

Idle Speed and Mixture Adjustment (Except Air Injection

Reactor System)

NOTE:
This adjustment should be performed

with engine at operating temperature and park-

ing brake applied.

1.
Remove Air Cleaner.

2.
Connect tachometer and vacuum gauge to engine, then

set hand brake and shift transmission into neutral.

3.
As a preliminary adjustment, turn idle mixture

screws lightly to seat and back out 1-1/2 turns.

CAUTION: Do not turn idle mixture screw

tightly against seat or damage may result.

4.
With engine running (choke wide open) adjust idle
speed screw to specified idle speed, (automatic

transmission in drive, synchronized transmission in

neutral).

5. Adjust idle mixture screw to obtain highest steady

vacuum at specified idle speed.

NOTE:
On air conditioned vehicles, turn air

conditioning to the "on" position and hold the

hot idle compensator valve closed while adjust-

ing idle speed and idle mixture screws.

NOTE:
On Rochester BV carburetors the idle

mixture screw should be turned out 1/4 turn

from the "lean roll" position. The definition

of "lean roll" point is a 20 to 30 rpm drop

in engine speed obtained by leaning the idle

mixture.

6. Repeat Steps 4 and5 as needed for final adjustment.

NOTE:
If necessary, final adjustment of the \

carburetor may be made with the air cleaner

installed.

7. Turn engine off, remove gauges and install air

clearer.

CHEVROLET CHASSIS SERVICE MANUAL

ENGINE FUEL 6M-3

Idle Speed and Mixture Adjustment (With Air Injection

Reactor System)

The following is the recommended procedure for Air

Injection Reactor System equipped engines.

NOTE: This adjustment should be performed

with engine at operating temperature and parking

brake applied.

1.
Remove air cleaner.

2.
Connect tachometer to engine, then set hand brake

and shift transmission into neutral.

3.
As a preliminary adjustment, turn idle mixture

screws lightly to seat and back out 3 turns.

CAUTION: Do not turn idle mixture screw

tightly against seat or damage may result."

4.
With engine running (choke wide open) adjust idle

speed screw to specified idle speed. (Automatic

transmission in dirve, synchronized transmission in

neutral).

5.
Adjust idle mixture screw (turn in) to "lean roll"

position; then turn screw out 1/4 turn (1/4 turn

rich from "lean roll"). The definition of "lean

roll" point is a 20 to 30 rpm drop in engine speed,

obtained by leaning the idle mixture.

NOTE: On air conditioned vehicles, turn air

conditioning "OFF" on in-line, 283, 327, and'

350 cu. in. engines, and turned "ON" and hot

idle compensator held closed on 396 and 427 cu.

in. engines.

6. Repeat Steps 4 and 5 as needed for final adjustment.

NOTE: If necessary, final adjustment of the
carburetor may be made with air cleaner

installed.

7.
Shut down the engine, remove gauges and install air

cleaner. *

Fast Idle Adjustment

Rochester
4MV and Holley

With fast idle lever on high step of cam and choke valve

open (engine warm) set fast idle to give specified engine

rpm. Adjust sejrew on Rochester 4MV and bend fast

idle lever *pn Holley. .

Choke Adjustment

With Remote Choke (Fig. 2c)

1.
Remove air cleaner and check to see that choke

valve and rod move freely.

2.
Disconnect choke rod at choke lever.

3.
Check choke adjustment as follows:

On all except 275 and 300 h.p. 327 cu. in. engines,

hold choke valve closed and pull.rod up against stop.

The top of choke rod end should be 1/2-1 rod diame-

ter above top of hole in choke valve lever.

On 275 and 300 h.p. 327 cu. in. engines, hold choke

valve closed and push rod down against stop on ther-

mostat bracket. The top of the choke rod should be

1/2-1 rod diameter below the top of the hole in the

choke lever.

4.
If necessary, adjust rod length by bending rod at

offset bend. (Bend must be such that rod enters

choke lever hole freely and squarely).

5.
Connect rod at choke lever and install air cleaner.

With Manual Choke (Carter YF)

1.
Remove air cleaner.

CHOKE VALVE

COMPLETELY

CLOSED

PULL UPWARD ON

ROD TO END OF

TRAVEL

BEND ROD

TO ADJUST
ROD IN BOTTOM

OF SLOT

BOTTOM OF

ROD SHOULD

BE EVEN WITH

TOP OF

HOLE
CHOKE VALVE

CLOSED

BOTTOM OF

ROD SHOULD

BE EVEN WITH

TOP OF HOLE

TOP OF ROD

SHOULD BE EVEN

WITH BOTTOM

OF HOLE (CHOKE

CLOSED)

BEND ROD TO

ADJUST

PULL DOWNWARD'

ON ROD TO CON-

TACT STOP

L6 (TYPICAL)

[

V8 327-275 HP

V8 350-295 HP
BEND ROD

TO ADJUST

PULL UPWARD ON

ROD TO CONTACT

STOP ON BRACKET

ALL V8 (EXCEPT 327-275 HP

AND 350-295 HP)

Fig.
2C—Remote Choke Adjustment

CHEVROLET CHASSIS SERVICE MANUAL

ENGINE FUEL 6M-4

Fig.
3C-Fuel Level Sight Plug

2.
Push hand choke knob in to within 1/8" of instru-

ment panel.

3.
Loosen choke cable clamp at carburetor bracket and

adjust cable through the clip until the choke valve

is wide open.

4.
Tighten cable clamp at carburetor bracket and check

operation of choke valve to ensure full closed and

wide open positions.

5. Install air cleaner.

Float Adjustment

Ho/fey (Model 4150
Center
Inlet & Model 2300)

1.
Remove air cleaner then remove the fuel level sight

plugs (Fig. 3c)

2.
With parking brake on, and transmission in neutral,

start the engine and allow it to idle.

3.
With the car on a level surface, the fuel level should

be on a level with the threads at the bottom of the

sight plug port (plus or minus 1/32 inch).

NOTE:
No float drop adjustment is required

on this carburetor.

4.
If necessary to adjust (either or both bowls), loosen

inlet needle lock screw and turn the adjusting nut

clockwise to lower or counter-clockwise to raise

fuel level, then tighten lock screw.

NOTE:
1/6 turn of adjusting nut equals ap-

proximately 1/16" fuel level change.

5. Allow a minute for fuel level to stabilize then re-

check the level at sight plug.

6. Readjust, if necessary, until proper level is obtained,

then install sight plug and air cleaner.

NOTE:
To assure proper secondary float level

setting it is advisable to accelerate primary

throttles slightly and hand operate secondary
throttle. This assures a stabilized secondary

fuel level.

Additional Adjustments

The following adjustments may be made without re-

moving the carburetor from the engine. For procedure

refer to Section 6M of the Overhaul Manual under the

carburetor being serviced.

Rochester BV

• Float

• Idle Vent

• Choke Rod (Fast Idle)

• Choke Vacuum Break

• Choke Unloader

Rochester 2GV

• Float

• Accelerator Pump

• Idle Vent

• Choke Rod (Fast Idle)

• Choke Vacuum Break

• Choke Unloader

• Secondary Throttle Opening

• Secondary Throttle Lockout

Rochester 4MV

• Float

• Accelerator Pumj)

• Idle Vent

• Air Valve

• Choke Rod

• Choke Vacuum Break

• Choke Unloader

• Air Valve Lockout

• Secondary Opening

• Secondary Lockout

Carter YF

• Float

• Idle Vent

• Choke Rod (Fast Idle)

• Choke Vacuum Break

• Choke Unloader

Holley 4160 and 4150
(Except End
Inlet)

• Float

• Air Vent Valve

• Accelerator Pump

• Choke Vacuum Break

• Choke Unloader

Holley 2300 and 4150
(End
Inlet)

• Air Vent Valve (except 2300)

• Accelerator Pump

• Choke Vacuum Break

• Choke Unloader

Removal

Flooding, stumble on acceleration and other perform-

mance complaints are, in many instances, caused by the

presence of dirt, water, or other foreign matter in the

carburetor. To aid in diagnosing the cause of the com-

plaint, the carburetor should be carefully removed from

the engine without draining the fuel from the bowl.

The contents of the fuel bowl may then be examined for

contamination as the carburetor is disassembled.

1.
Remove air cleaner and gasket.

2.
Disconnect fuel and vacuum lines from carburetor.

CHEVROLET CHASSIS SERVICE MANUAL

ENGINE FUEL 6M-6

Fig.
6C-Choke Coil-V8 Engine

• Remove bracket and choke coil assembly.

WITH ROCHESTER 4MV AND

HOLLEY CARBURETORS

• Remove the choke coil shield by prying with a

screw driver in the cut out provided then lift

shield carefully over rod.

• Remove choke rod, bracket screw and choke

coil assembly
3.
Install a new choke coil assembly being sure the

locating tab is in the forward hole of the intake

manifold then install mounting screw.

4.
Complete installation as follows:

WITH ROCHESTER 2GV CARBURETOR

• Check that the choke rod eye of the coil is

below the stop tab on the bracket then install

the choke
ro and adjust if necessary.

• Install the choke coil shield over the choke coil

and move shield to best fit along manifold.

WITH ROCHESTER 4MV AND

HOLLEY CARBURETORS

• Install the choke rod and adjust as necessary

(without choke coil shield installed).

• Disconnect choke rod upper end and lower choke

coil shield over choke rod and install over choke

coil.

• Move shield to best fit along manifold and con-

nect upper end of choke rod.

5. Be sure choke valve moves freely from full open

to full closed position.

6. Start and warm up the engine and check operation

of the choke.

7. Install the air cleaner.

Throttle Linkage Adjustment (Fig. 7c or 8c)

1.
Disconnect throttle rod swivel at throttle lever on

carburetor.

2.
On automatic transmission equipped vehicles dis-

connect TV rod at throttle lever.

3.
Hold carburetor throttle in wide open position, push

throttle rod rearward (to position accelerator pedal

at the floor mat) and adjust swivel to just enter hole

in throttle lever.

4.
Connect swivel to throttle lever and install accelera-

tor return spring.

CAMARO & CHEVY II V8

CHEVELLE & CHEVROLET

V8

CAMARO
&
CHEVY
II

V8

CHEVELLE &

CHEVROLET V8
ALL SERIES

IN LINE

ALL SERIES

INLINE

Fig.
7C—Throttle Linkage—Chevrolet, Chevelle, Chevy II and Camaro

CHEVROLET CHASSIS SERVICE MANUAL

SECTION 6T

AIR INJECTION REACTOR SYSTEM

INDEX

Page

General Description 6T-1

Maintenance Procedures 6T>1

Drive Belt. ...-..' 6T-1

Inspection 6T-1

, Adjustment . . 6T-1

Replacement 6T-1

Drive Pulley . . . . 6T-1

Replacement 6T-1

Pump Pulley ....................... 6T-1

Replacement. 6T-1

Air Manifold, Hose and Tube
...........>*.
6T-2

Inspection . . 6T-2

Replacement 6T-2

Check Valve (s) 6T-3
Page

Inspection 6T-3

Replacement . . 6T-3

Mixture Control Valve 6T-3

Inspection 6T-3

Replacement 6T-3

Air Injection Tube 6T-4

Inspection . . . ... . . . .... 6T-4

Replacement 6T-4

Air Injection Pump 6T-4

Inspection 6T-4

Replacement . 6T-4

Pressure Relief Valve Replacement 6T-4

Special Tools 6T-5

GENERAL

The Air Injection Reactor (A.I.R.) System (fig. 1) con-

sists of: the air injection pump (with necessary brackets

and drive attachments), air injection tubes (one for each

cylinder), a mixture control valve, check valves (one for

In Line engines, two for V8 engines) and air manifold as-

semblies, tubes and hoses necessary to connect the

various components.

Carburetors and distributors for engines with the

A.I.R. System are designed, particularly, for these en-

gines;
therefore, they should not be interchanged with or

replaced by a carburetor or distributor designed for an

engine without the A.I.R. System.

The air injection pump (fig. 2) picks up fresh filtered

air from the air cleaner, compresses the air and injects

it through the air manifolds, hoses and injection tubes

into the exhaust system in the area of the exhaust valves.

The fresh air ignites and burns the unburned portion of

the exhaust gases in the exhaust system, thus minimizing

exhaust contamination.

The mixture control valve (fig. 3) when triggered by a

sharp increase in manifold vacuum, supplies the intake

manifold with fresh filtered air to lean out the fuel-air
DESCRIPTION

mixture and prevent exhaust system backfire.

The check valve(s) prevent exhaust gases from entering

and damaging the air injection pump, as back flow can

occur even under normal operating conditions.

When properly installed and maintained, the A.I.R.

System will keep exhaust emissions well below require-

ments. However, if any A.I.R. component or any engine

component that operates in conjunction with the A.I.R.

system should malfunction, the exhaust emissions might

be increased.

Because of the relationship between "Engine Tune

Up"
and "Unburned Exhaust Gases", the condition of

Engine Tune Up should be checked whenever the A.I.R.

System seems to be malfunctioning. Particular care

should be taken in checking items that affect fuel - air

ratio such as the crankcase ventilation system, the

carburetor and the carburetor air cleaner.

Because of the similarity of many parts, typical illus-

trations and procedures are used except where specific

illustrations or procedures are necessary to clarify the

operation. For Repair Procedures on the Air Injection

Pump,
refer to the Passenger Chassis Overhaul Manual.

MAINTENANCE PROCEDURES

Drive Belt

Inspection

• Inspect drive belt for wear, cracks or deterioration

and replace if required.

• Inspect belt tension and adjust if below 50 lb. using a

strand tension gauge.

Adjustment

• Loosen pump mounting bolt and pump adjustment

bracket bolt.

• Move pump until belt is tight (55±5 lb. used belt or

75±5 lb. new belt using a strand tension gauge) then

tighten adjustment bracket bolt and mounting bolt.

CAUTION: Do not pry on the pump housing.

Distortion of the housing will result in extensive

damage to the Air Injection Pump.

Replacement

• Loosen pump mounting bolt and pump adjustment
bracket bolt then swing pump until drive belt may be

removed.

• Install a new drive belt and adjust as outlined above.

Drive Pulley .

Replacement

• Remove drive belt as outlined above then replace

drive pulley.

• Install and adjust drive belt as outlined above.

Pump Pulley

Replacement

• Hold pump pulley from turning by compressing drive

belt then loosen pump pulley bolts.

• Remove drive belt as outlined above then remove

pump pulley.

• Install pump pulley with retaining bolts hand tight.

CHEVROLET CHASSIS SERVICE MANUAL

AIR INJECTOR REACTOR SYSTEM
6T-2

AIR

MANIFOLD
MIXTURE

CONTROL

VALVE

AIR

INJECTION

PUMP

IN LINE
MIXTURE

CONTROL

VALVE

AIR INJECTION

PUMP

CHECK

VALVE

V8

Fig.
I—Air
Injection Reactor System (Typical)

• Install
and
adjust drive belt
as
outlined above.

• Hold pump pulley from turning
by
compressing drive

belt then torque pump pulley bolts
to 25 ft. lbs.

• Recheck drive belt tension
and
adjust
if
required.

Air Manifold, Hose and Tube

Inspection (Fig. 4)

• Inspect
all
hoses
for
deterioration
or
holes.

• Inspect
all
tubes
for
cracks
or
holes.

PUMP

HOUSING

91

DRIVE V

HUB

PRESSURE

RELIEF VALVE
•H
PUMP
'

Mm ^
COVER

A.

J^HTEXHAUST

wBBE
TUBES

SB

^1 INTAKE

JH TUBE
• Check
all
hose and tube connections.

• Check
all
tube
and
hose routing. Interference
may

cause wear.

•
If a
leak
is
suspected
on the
pressure side
of the

system
or any
tubes and/or hoses have been discon-

nected
on the
pressure side,
the
connections should

be checked
for
leaks with
a
soapy water solution.

With
the
pump running, bubbles will form
if
aleak

exists.

Replacement

•
To
replace
any
hose and/or tube, note routing then

remove hose(s) and/or tube(s)
as
required.

CAUTION:
The 1/4"
pipe threads
at the
cylin-

der head
(In
Line)
or
exhaust manifold
(V8) are

VALVE
IN

OPEN

POSITION
INLET

VALVE
IN

CLOSED

POSITION

DIAPHRAGM

POSITIONS
SIGNAL
LINE

CONNECTION

ALVE

Fig.
2—Air Injection Pump
Fig.
3—Mixture Control Valve

CHEVROLET CHASSIS SERVICE MANUAL

ENGINE-ELECTRICAL 6Y-8

1

FIELD RELAY^I^p2

"LATCH"
^PFN?^

"P1
TERMINAL
JyJvJCTl^

NO. 2 TERMINAD^5^^^«

NO.
3 TERMINAL ^S5«£

NO.
4 TERMINAL ^^^
m

# / VOLTAGE

¥ REGULATOR

1
ACCESS PLUG TO

VOLTAGE ADJUSTMENT

No 4 TERMINAL

Double Contact

Fig.
2c—Voltage Regulator Assemblies
Transistor

regulator to handle the higher field current and enables it

to absorb the increased inductive voltages of the field

coil with satisfactory contact point life.

The double-contact regulator assembly (fig. 2c) con-

sists of a double contact voltage regulator unit and a field

relay unit. This unit uses two sets of contact points on

the voltage regulator unit to obtain desired field excita-

tion under variable conditions. Internal circuit wiring

diagrams of the double contact regulator are shown in

Figures 3c and 4c.

The transistor regulator (fig. 2c) is an assembly com-

posed principally of transistors, diodes, resistors, a

capacitor, and a thermistor to form a completely static

voltage regulating unit in combination with a conventional

vibrating type field relay.

The transistor is an electrical device which limits the
generator voltage to a preset value by controlling the

generator field current. The diodes, capacitor and re-

sistors act together to aid the transistors in controlling

the generator voltage. This is the only function that the

regulator performs in the charging circuit. The

thermistor provides a temperature-compensated voltage

setting. Wiring diagrams of the transistor regulator are

shown in Figures 3c and 4c.

The voltage at which the generator operates is deter-

mined by the regulator adjustment. The regulator voltage

setting can be adjusted externally by removing a pipe plug

in the cover (fig. 2c) and turning the adjusting arm inside

the regulator. This procedure is explained in the followr

ing section, and permits regulator adjustments without

removing the cover.

FUSIBLE

DOUBLE CONTACT
FUSIBLE LINK-^
JUNCTION HORN

BLOCK RELAY

RESISTOR

Q FIELD Q>

DELCOTRON TR-

TRANSISTOR
FUSIBLE LINK-

Fig.
3c-Circuity - Voltage Regulator Assemblies (Except Corvette)

CHEVROLET CHASSIS SERVICE MANUAL

ENGINE-ELECTRICAL 6Y-10

circuit. Make absolutely certain all connections in

the circuit are secure.

5.
Do not short across or ground any of the terminals

on the generator or regulator.

6. Do not attempt to polarize the generator.

7.
Do not disconnect lead at generator without first dis-

connecting battery ground cable.

Trouble in the A.C. charging system will usually be

indicated by one or more of the following conditions:

1.
Faulty indicator lamp or ammeter operation.

2.
An undercharged battery (usually evidenced by slow

cranking speeds).

3.
An overcharged battery (usually evidenced by exces-

sive battery water usage).

4.
Excessive generator noise or vibration.

Described below are a series of on-the-vehicle quick

checks which are designed to assist the service tech-

nician in locating troubles within the various components

of the engine electrical system. Additional checks, ad-

justments and overhaul procedures of these components

are also described in the "Charging Systems—Service

Operations Section" and should be referred to as

necessary.

STATIC CHECKS

Before making any electrical checks, perform the fol-

lowing static checks:

1.
Check for loose fan belt.

2.
Check for defective battery. (Refer to Battery).

3.
Inspect all connections, including the slip-on con-

nectors at the regulator and Delcotron.

NOTE: Do not short field to ground to check if

generator is charging since this will seriously

damage the charging system.

SYSTEM CONDITION TEST

This test is used .to indicate the overall condition of the

charging system (both good and defective) and to isolate

the malfunctioning unit if the system is defective.

NOTE: On Corvette models difficulty may be

encountered -when attempting to make the re-
quired test connections at the voltage regulator.

It is advisable to remove the regulator from its

mounting location to perform the necessary con-

nections at the regulator for the following tests

but make sure unit is grounded.

1.
With ignition off, perform the prescribed Static

Checks outlined in this section. Then set hand brake

and shift transmission
into
neutral.

2.
Connect a voltmeter from junction block relay to

ground at regulator base.

CAUTION: Be sure meter clip does not touch a

resistor or terminal extension under regulator,

3.
Connect a tachometer on engine.

4.
Models equipped with Indicator Lamp: Turn ignition

switch on "ON" position and check indicator lamp.

If lamp fails to glow, perform appropriate tests and

corrections (Indicator Lamp Circuit Tests) before

continuing.

Models equipped with Ammeter: Turn ignition

switch to "ACC" with an accessory on and check

ammeter. If ammeter fails to read discharge, check

ammeter circuit before continuing.

5.
Models equipped with Indicator Lamp: If lamp glows,

start the engine and run' it at 1500 rpm or above.

Check indicator lamp. If lamp fails to go out, per-

form appropriate test and corrections (Indicator

Lamp Circuit Test) before continuing.

Models equipped with Ammeter: If ammeter reads

discharge, start the engine and observe ammeter. If

meter fails to move toward charge (from original

position), perform appropriate test and corrections

(Field Circuit Tests) before continuing.

NOTE: At this point a field circuit has been

established and any other problem will lie in

generator or regulator.

6. Turn on high-beam headlights and heater blower

motor to high speed, run engine at or above 1500

rpm (for a few minutes, if necessary) and read the

voltage on meter.

AIR GAP

ADJUSTING NUT

ONLY

ADJUSTING SCREW

(Turn To Adjust

Voltage Setting)

Fig.
6c—Adjusting Voltage Setting

CHEVROLET CHASSIS SERVICE MANUAL

ENGINE-ELECTRICAL 6Y-11

I
BAT
JUNCTION BLOCK
DELCOTRON

—GRQ

BATTERY

&HJVVWV

0 VA OHM TEST RELAY >

RESISTOR [ 1 d

FUSIBLE

LINK

TO CRANKING

MOTOR
Ik

REGULATOR

VOLTMETER

FUSIBLE LINK

IGN.
SWITCH

Fig.
7c—Voltage Setting Test Connections

NOTE:
Voltage will not greatly exceed 12-1/2

volts until the battery develops a surface charge,

a few minutes generally, unless the battery is

severely discharged or is hot.

If reading is:

a. 12-1/2 volts or more, turn off electrical loads,

stop engine and proceed to Step 7.

b.
Less than 12-1/2 volts, perform "Delcotron Out-

put Test-Voltmeter Method."

(1) Delcotron tests bad—refer to "Service Op-

erations" and repair Delcotron, then repeat

Step 6.

(2) Delcotron tests good—disconnect regulator

connector, remove regulator cover and recon-

nect the connector. Then repeat Step 6 and

turn voltage adjusting screw (fig. 6c) to raise

setting to 12-1/2 volts. On transistor regula-

tor remove pipe plug (fig. 6c), insert screw

driver into slot and turn clockwise one or two

notches to increase setting. Turning counter-

clockwise decreases setting. For each notch

moved, the voltage setting will change ap-

proximately .3 volt. Turn off loads, stop en-

gine and proceed to Step 7. If 12-1/2 volts

cannot be obtained, install a new regulator and

repeat Step 6.

ADJUSTING REGULATOR VOLTAGE

7. Connect a 1/4 ohm-25 watt fixed resistor (purchased

commercially) into the charging circuit at the junc-

tion block as shown in Figure 7c.

NOTE:
Between both leads and the terminal.

8. Run engine at 1500 rpm or above for at least 15

minutes of warm-up, then cycle regulator voltage

control (by disconnecting and re-connecting regulator

connector) and read voltage.

If voltage is 13.5 to 15.2, the regulator is okay.

If voltage is not within 13.5 to 15.2 volts, leave en-

gine running at 1500 rpm or above and:
a. Disconnect four terminal connector and remove

regulator cover. Then re-connect four terminal

connector and adjust voltage to i4.2 to 14.6.

(Refer to Step 6 and fig. 6c).

b.
Disconnect four terminal connector and reinstall

regulator cover, then reinstall connector.

c. Continue running engine at 1500 rpm for 5-10

minutes to re-establish regulator internal

temperature.

d. Cycle regulator voltage by disconnecting and re-

connecting regulator connector. Read voltage. A

reading between 13.5 and 15.2 indicates a good

regulator.

CAUTION: Be sure four terminal regulator

connector is disconnected when removing or in-

stalling cover. This is to prevent regulator

damage by short circuits.

DELCOTRON OUTPUT TEST

Ammeter Method (Fig. 8c)

1.
Disconnect the battery ground cable at the battery.

2.
Disconnect the red wire at Delcotron battery termi-

nal and connect an ammeter in series between the

wire and terminal.

3.
Connect a voltmeter from battery terminal to a good

ground on the generator.

4.
Disconnect the F-R terminal connector at the

Delcotron.

5. Connect the jumper wire between Delcotron "F" and

battery terminals.

6. Connect the battery ground cable at the battery.

7. Connect an adjustable carbon pile across the battery

posts.

8. Start the engine and slowly bring the speed to 1500

RPM and at the same time adjust the carbon pile

load to hold the voltage at 14 volts.

9. Read the amperage and compare with a specifications

chart.

CHEVROLET CHASSIS SERVICE MANUAL

ENGINE-ELECTRICAL 6Y-J2

Fig.
8c—Ammeter Method Test Connections

10.
Turn off ignition, disconnect battery ground cable,

and remove all test equipment.

11.
li the Delcotron meets the test specifications, the

problem is not in the generator.

12.
Ti the Delcotron fails to meet the test specifications,

remove it and perform bench tests and make repair

needed.

DELCOTRON DIODE AND FIELD TEST (Fig. 9c)

NOTE:
These tests will indicate good,, shorted

or open field or shorted diode but will not indi-

cate a failed open diode. If output was low and

following tests show good, refer to service op-

erations to determine cause and repair.

1.
Disconnect battery ground cable at battery.

2.
Positive diodes (Test A) connect an ohmmeter be-

tween "R" terminal and "BAT" terminal and note

Fig.
9c-Deicotron Diode and Field Test
reading, then reverse the leads at same terminals

and note this reading. Meter should read high re-

sistance in one direction and low in the other.

3.
Negative diodes (Test B) connect ohmmeter between

"R" terminal and "GRD" and note reading, then

reverse the leads and note this reading. Meter

should read high in one direction and low in the

other.

NOTE:
A high or low reading in both directions

indicates a defective diode.

4.
Open Field Check:

a. Connect an ohmmeter from "F" terminal to

"GRD"
terminal stud and note reading on the

lowest range scale. Meter should read 7 to

20 ohms.

b.
If meter reads zero or excessively high resist-

ance, the Delcotron is faulty.

5. If above tests indicate a defective Delcotron, remove

and completely check Delcotron as outlined under

''Service Operations".

INDICATOR LAMP/INITIAL FIELD

EXCITATION CIRCUIT TESTS (Fig. 10c)

On standard models the indicator lamp circuit provides

initial field excitation (causing lamp to glow). The light

is cancelled by closing the field relay which applies bat-

tery voltage to both sides of bulb (bulb goes out).

The indicator light should glow when ignition switch is

"ON"
and go out almost immediately when engine starts.

Ammeter equipped vehicles use the same initial field

excitation and control circuits as the indicator lamp ex-

cept the lamp is omitted. The continuity tests on both

type vehicles can be made as follows:

If Lamp Fails to Glow or Ammeter Fails to

Function the Possible Causes are:

1.
Faulty bulb or bulb socket.

2.
Faulty ammeter.

3.
An open circuit in wiring, regulator, or field.

4.
A shorted positive diode—(may also cause glow with

ignition switch "OFF").

TEST AS FOLLOWS:

1.
Disconnect connector from regulator and turn

ignition switch to "ON". Connect a test lamp from

connector terminal "4" to ground (fig. 10c, Step 1)

and note test lamp.

a. Lamp fails to glow—check for faulty bulb, socket

or open circuit between switch and regulator con-

nector. Repair as needed.

b.
Light goes on—failure is in regulator, Delcotron,

or wire between "F" terminals on regulator and

Delcotron. Go to Step 2.

2.
Disconnect lamp lead at ground end and connect be-

tween connector "F" and "4" terminals (fig. 10c,

Step 2), and note lamp:

a. Test Lamp glows—problem is in regulator. An

open circuit in regulator or relay is stuck dosed.

See "Service Operations" for repair.

b.
Fails to glow—problem is in wire between "F"

terminals on generator and regulator or infield

windings. Go to Step 3.

3.
Disconnect test lamp at connector "F" terminal and

CHEVROLET CHASSIS SERVICE MANUAL