Tune-Up - v6 Chevrolet Pickup C10

ENGINE IDENTIFICATION

Engines are identified by the eighth character of the Vehicle Identification Number (VIN). The VIN number plate is attached to the left top side of dash.

VIN ENGINE CODE

TUNE-UP NOTES

Note. When performing tune-up procedures described in this article, the following notes and precautions must be observed

1. Due to changes and corrections, always refer to Engine Tune-Up Decal in engine compartment before attempting tune-up. In the event of a conflict between specifications given in this manual and decal specifications, decal specifications prevail.
2. When performing tune-up on vehicles equipped with a catalytic converter, do not allow or create a condition of engine misfire in one or more cylinders for an extended period of time. Damage to converter from overheating may occur due to loading with unburned fuel.

ENGINE COMPRESSION

When making compression checks, disconnect the ignition switch connector Pink wire from high energy ignition system. With air cleaner removed and throttle and choke wide open, crank engine through at least 4 compression strokes.

COMPRESSION SPECIFICATIONS

SPARK PLUGS

SPARK PLUG SPECIFICATIONS

SPARK PLUG TYPE

HIGH TENSION WIRE RESISTANCE

Carefully remove ends of wire from spark plug and distributor. Spark plug boot should be turned 1/2 turn before removing. Using an ohmmeter, check resistance while gently twisting wire. If resistance is not to specifications, or fluctuates from infinity to any value, replace cable.

HIGH TENSION WIRE RESISTANCE (OHMS)

VALVE CLEARANCE

All engines use hydraulic lifters.

VALVE CLEARANCE ADJUSTMENT

VALVE ARRANGEMENT

1. E-I-I-E-I-E (Left bank, front to rear).
2. E-I-E-I-I-E (Right bank, front to rear).

DISTRIBUTOR

Federal models are equipped with a Delco High Energy Ignition (HEI) distributors. California models with Delco HEI-EST Electronic Spark Timing (HEI-EST) distributors.

California models with 4.3L engines are equipped with Delco HEI-EST distributors with Electronic Spark Control (ESC).

2.8L Firing Order & Timing Mark (Magnetic Probe Is Located At 9.5 Degrees ATDC). Scheme 18

Federal Models

1. Install timing light with an adapter between No. 1 spark plug and No. 1 spark plug wire, or use an inductive type pickup. Do not puncture wire.
2. Check or adjust ignition timing with engine at normal operating temperature, distributor advance line disconnected and plugged, and automatic transmission in "D" (auto. trans.) or Neutral (man. trans.).

California Models

1. Install timing light with an adapter between No. 1 spark plug and No. 1 spark plug wire, or use an inductive type pickup. Do not puncture wire. Disconnect 4-wire connector at distributor.
2. Check or adjust ignition timing with engine at normal operating temperature and automatic transmission in "D" (if equipped). Reconnect 4-wire connector. Clear trouble codes by removing ECM power fuse for 10 seconds.

4.3L Firing Order & Timing Mark. Scheme 19

IGNITION TIMING SPECIFICATIONS (DEGREES BTDC @ RPM)

2.8L - Federal Models

1. Make adjustments with engine at normal operating temperature, choke full open, air cleaner installed and air conditioning off (if equipped). Disconnect EGR vacuum hose and canister purge hose at canister. Disconnect solenoid wire (if equipped). Place transmission in "D" (auto. trans.) or Neutral (man. trans.).
2. Set curb idle speed with idle speed screw. If vehicle is equipped with air conditioner, disconnect compressor lead and turn A/C on. Connect solenoid wire (if equipped) and all hoses. Open throttle slightly to allow solenoid to extend. Adjust solenoid idle by turning screw in back of solenoid.

2.8L - California Models

1. Make adjustments with engine at normal operating temperature, choke fully open, air cleaner installed and A/C off (if equipped). Disconnect vacuum hose from carburetor port "C" (to EGR/Canister Purge TVS) and cap port.
2. Disconnect solenoid wire (if equipped). Place transmission in "D" (auto. trans.) or Neutral (man. trans.). Set curb idle speed with idle speed screw.
3. If vehicle is equipped with A/C, disconnect compressor lead and turn A/C on. Connect solenoid wire (if equipped) and all hoses. Open throttle slightly to allow solenoid to extend. Adjust solenoid idle by turning screw in back of solenoid.

IDLE SPEED (RPM)

4.3L - Federal Models

1. Set ignition timing to specifications. Disconnect and plug vacuum hose at EGR valve, canister purge and purge signal. Place transmission in "D" (auto. trans.) or Neutral (man. trans.). Adjust curb idle speed using idle speed screw.
2. Disconnect and plug vacuum hose from Stepped Speed Control Actuator (SSCA). Connect a 12 in. Hg vacuum source to SSCA. Ensure throttle opens and SSCA is fully extended. Adjust SSCA idle speed by turning screw.
3. Remove vacuum source and connect vacuum hose. Stop engine and reconnect all hoses.

STEPPED SPEED CONTROL ACTUATOR SPECIFICATIONS

Note. On California models, ISC and SSCA are controlled by ECM. Adjustment is not usually necessary.

Scheme 20

1. Check identification letter on ISC plunger. (Scheme 20) If no letter appears, remove plunger from unit using adjustment tool (J-29607 or BT-8022).
2. Measure and record length of plunger from back side of plunger head to end of screw. This is dimension "A". (Scheme 20) Install plunger so that distance measured from back side of plunger to ISC nose piece is less than dimension "B".
3. Remove air cleaner, disconnect and plug EGR and canister purge hoses. Connect tachometer to engine. Connect dwell meter (set on 6-cylinder scale) to mixture control solenoid dwell lead. Turn A/C off. Start engine and run until meter starts to vary. (Scheme 20): Idle Speed Control (ISC) Adjustment NOTE: Do not disconnect or connect ISC connector with ignition on as damage to ECM may occur.
4. Turn ignition off and unplug connector from ISC motor. Retract plunger by applying 12V to terminal "C" of ISC motor connection and ground lead to terminal "D" of ISC motor connection. (Scheme 21)
5. Start engine and wait until dwell meter begins to vary. Set parking brake, block drive wheels and place transmission in "D" (auto. trans.) or Neutral (man. trans.). With plunger fully retracted, adjust idle stop screw to curb idle specification.
6. Place transmission in "P" (auto. trans.). Fully extend plunger by applying 12V to terminal "D" and ground terminal "C". Leave power applied only long enough to extend plunger.
7. Using adjustment tool (J-29607 or BT-8022) adjust solenoid idle speed on vehicles with manual transmissions. Preset plunger to 1500 RPM on vehicles with automatic transmissions, place transmission in "D", then adjust solenoid idle speed using adjustment tool.
8. Recheck solenoid idle speed with voltage applied to motor. After adjustment of plunger, measure distance from back side of plunger to ISC nose piece. Dimension "B" must not exceed specification shown.
9. Fully retract plunger and turn ignition off. Disconnect battery leads, tachometer and dwell meter. Connect 4-terminal connector.
10. Disconnect and plug vacuum hose from Stepped Speed Control Actuator (SSCA). Connect a 12 in. Hg vacuum source to SSCA. Ensure throttle opens and SSCA is fully extended. Adjust SSCA idle speed by turning screw.
11. Remove vacuum source and connect vacuum hose. Stop engine and reconnect all hoses.

ISC Motor Connections. Scheme 21

IDLE SPEED CONTROL PLUNGER SPECIFICATIONS

IDLE MIXTURE

Note. Idle mixture adjustment is not a normal tune up procedure. Idle mixture should be checked only if vehicle fails emissions testing or carburetor has been disassembled.

Mixture Screw Plug Removal

1. Remove carburetor from engine. Invert throttle body and make two parallel cuts on each side of the locator point with a hacksaw. Cuts should not extend more than 1/8" (3.2 mm) beyond the locator point. (Scheme 22)
2. Disconnect and plug vacuum advance hose. Connect tachometer to engine. Adjust timing and reconnect vacuum advance hose. Set idle speed.
3. Disconnect crankcase ventilation tube from air cleaner. Using adapter (J-26911), insert host with rubber stopper (from propane valve) into air cleaner snorkel. Be sure propane cartridge is vertical.
4. With engine idling in "D" (auto. trans.) or neutral (man. trans.), open propane supply control valve safely. Engine speed will increase. Add propane until engine speed begins to drop from over-richness. Note maximum enriched idle RPM.
5. The maximum enriched idle RPM is the idle RPM plus propane enrichment RPM. Engine speed should rise above normal idle by amount specified. If so, mixture is correct. Go to step 9).
6. If speed is incorrect, remove idle mixture screw plugs. Carburetor must be removed and a punch driven through bottom of throttle body to remove plug. Seat screws, then back out 3 turns.
7. Place transmission in "D" (auto. trans.). Back out screw slowly until maximum idle speed is reached. Set maximum enriched idle speed.
8. Turn each mixture screw in (clockwise), 1/8 turn at a time until idle speed is correct. Recheck maximum enriched speed with propane. If incorrect repeat step 7).
9. Check and adjust fast idle speed. Turn off engine. Remove propane tool, connect crankcase ventilation tube and reconnect all vacuum hoses.

Idle Mixture Plug Removal (2.8L Engines Shown). Scheme 22

4.3L Federal Models (M4ME Only)

1. Warm engine to normal operating temperature and turn A/C off. Set parking brake and block drive wheels. Disconnect and plug vacuum advance hose. Connect tachometer to engine. Adjust timing and reconnect vacuum advance hose. Set idle speed.
2. Disconnect crankcase ventilation tube from air cleaner. Using adapter (J-26911), insert hose with rubber stopper (from propane valve) into air cleaner snorkel. Be sure propane cartridge is vertical.
3. With engine idling in "D" (auto. trans.) or Neutral (man. trans.), open propane supply control valve slowly. Engine speed will increase. Add propane until engine speed begins to drop from over-richness. Note maximum enriched idle RPM.
4. If enriched idle speed is within specification, idle mixture is correct. Go to step 8). If enriched idle speed is not correct, remove carburetor and remove idle mixture plugs.
5. Install carburetor on engine, lightly seat idle mixture screws then back out equally, just enough to that engine will run. Place transmission in "D" (auto. trans.) or Neutral (man. trans.).
6. Back out each screw 1/8 turn at a time until maximum idle speed is obtained. Set idle speed to enriched idle specification. Turn mixture screws in 1/8 turn at a time until idle speed reaches value given on Engine Tune-Up Decal.
7. Recheck enriched idle speed with propane. If not within specification, repeat adjustment beginning at step 5). After adjustment is completed, seal idle mixture screw openings using RTV.
8. Check idle speed and fast idle speed, adjust if necessary. Turn off engine, remove propane adapter and connect crankcase ventilation tube. Unplug and reconnect vacuum hoses and install air cleaner.

PROPANE ENRICHED RPM

2.8L California Models (E2SE Only)

1. Remove carburetor from engine, and remove idle mixture screw plug. Turn mixture screw in until lightly seated and back out 4 turns. If plug in air horn (covering idle air bleed) has been removed, replace air horn.
2. Remove vent stack screen assembly to gain access to lean mixture screw. Using adjustment tool (J-286096 or BT-7928), turn lean mixture screw until lightly bottomed then back out 2 1/2 turns.
3. Install carburetor on engine. Do not install air cleaner or gasket. Disconnect bowl vent line at carburetor. Disconnect EGR valve hose and canister purge hose at carburetor. Cap carburetor ports.
4. Disconnect carburetor-to-temperature sensor hose on air cleaner and plug open hose. Connect a dwell meter lead to mixture control solenoid dwell test lead (Green connector).
5. Set dwell meter to 6-cylinder position. Connect a tachometer to distributor lead (Brown connector). Transmission should be in Park (auto. trans.) or Neutral (man. trans.). Start engine and bring to operating temperature. NOTE: Tachometer should be connected to distributor side of tach filter if vehicle is equipped with a tachometer.
6. Run engine on high step of fast idle cam for at least 3 minutes, until engine is in closed loop operation (dwell meter varying). Push TPS down and insert a 1/8" (3 mm) spacer between plunger and lever.
7. Run engine at 3000 RPM and adjust lean mixture screw slowly to allow time for dwell to stabilize. Turn screw to obtain an average dwell of 35°. If unable, inspect idle system for leaks or restrictions.
8. Disconnect mixture control solenoid when cooling fan is in off cycle. Check for an RPM change of at least 50 RPM. If RPM does not change, check idle air bleed circuit for leaks or restrictions.
9. Run engine at 3000 RPM for a few moments and none dwell reading. Dwell should show an average of 35°. If not reset lean mixture screw. Then reset idle mixture screw to obtain 25° dwell. (Scheme 23)
10. When dwell has been set connect all hoses, install vent screen and air cleaner. Set idle speed and remove 1/8" (3 mm) spacer.

2.8L E2SE Idle Mixture Adjustment. Scheme 23

4.3L California Models (E4ME Only)

1. With engine idling and choke wide open, insert float gauge (J-34935-1 or BT-8420-A) in vent hole (slot) and allow gauge to float freely. Do not press down on gauge as flooding may occur.
2. Observe mark on gauge that lines up with top of air casting. Float setting should be within 2/32' of specified float level. If not within specifications, remove air horn and adjust float.
3. Insert float gauge in "D" shaped vent hole of air horn casting, next to idle Air Bleed cover. It may be necessary to file material off gauge to allow it to enter vent hole.
4. With engine off and air cleaner and gasket removed, lightly press down on gauge and release. Observe that gauge moves freely. With gauge released, observe mark on gauge that lines up with top of air horn casting. Record reading.
5. Lightly press down on gauge until it bottoms, and record reading of gauge mark that lines up with top of air horn casting. Total plunger travel must be within 1/16" and 3/16" (1.6 mm and 4.8 mm).
6. If plunger travel is within specifications and dwell reading at 3000 RPM is 10°-50°, go to step 7). If travel is incorrect, carburetor must be disassembled and travel adjusted.
7. Stop engine and remove air cleaner and gasket, cover internal bowl vents and air inlets to air bleed valve with masking tape. Carefully drill pop rivets retaining air bleed valve cover. Drive out shanks with a drift and small hammer.
8. Remove and discard air bleed valve cover along with masking tape. Install air bleed valve gauging tool (J-33815-2 or BT-8253-B) in "D" shaped vent hole of air horn casting. Upper end of tool should be positioned over open cavity, next to idle air bleed valve.
9. Lightly press down on gauging tool so that solenoid plunger is against idle stop. Adjust idle air bleed valve so that gauging tool will pivot over and just contact top of valve.
10. Remove carburetor from engine and remove idle mixture plugs. Using adjustment tool (J-292030 or BT-7610-B), turn each idle mixture adjustment screw clockwise until lightly seated. Back out idle mixture screws 3 turns.
11. Install carburetor on engine, but do not install air cleaner or gasket. Disconnect vacuum hose to canister purge valve and plug it. Start engine and warm to operating temperature.
12. Place transmission in "D" (auto. trans.) or Neutral (man. trans.). Adjust both idle mixture screws equally and in 1/8 turn increments until dwell reading varies within 25°-35°. Bring dwell reading as close as possible to 30°.
13. If reading is too high, turn idle mixture screws clockwise. If reading is too low, turn idle mixture screws counterclockwise. After adjustment is completed, seal idle mixture screw openings using RTV. Check idle speed and fast idle speed, adjust if necessary.

E4ME FLOAT LEVEL SPECIFICATIONS

COLD (FAST) IDLE RPM

Note. Procedures listed are for carbureted engines with adjustable fast idle.

Warm up vehicle. Remove and plug EGR and purge control vacuum lines. Place fast idle screw on highest step of fast idle cam. Start engine. On ECM controlled engines, wait until engine enters closed loop operation. Adjust fast idle screw to obtain fast idle RPM.

FAST IDLE RPM

THROTTLE POSITION SENSOR (TPS) ADJUSTMENT

Note. DO NOT remove TPS adjustment screw plug unless TPS is not adjusted correctly or it is necessary to replace air horn assembly, float bowl, TPS sensor, or TPS adjustment screw.

2.8L TBI

Connect digital voltmeter between TPS connector terminals "B" and "C" using jumper wires. With ignition on and engine stopped, TPS voltage should be .42-.56 volts. Rotate TPS to obtain correct voltage reading. Turn ignition off and remove jumper wires. Tighten TPS mounting screws. Recheck voltage reading to ensure sensor did not move.

2.8L TPS Adjustment Screw Location. Scheme 24

4.3L (E4ME Only)

1. Using a 5/64" (2 mm) drill, drill a 1/16" to 1/8" deep hole in aluminum plug covering TPS adjustment screw. Use care not to damage screw head. (Scheme 25)
2. Start a No. 8 1/2" long self-tapping screw in drilled hole, turning screw in only far enough to ensure good thread engagement. Using a screwdriver between screw head and air horn, pry out plug.
3. Using tool (J-28696), remove TPS adjustment screw. Connect a digital voltmeter from TPS connector center terminal "B" to bottom terminal "B" to bottom terminal "C". With ignition on, engine stopped, install TPS adjustment screw to obtain specified voltage with A/C off and throttle at idle.
4. After adjustment, install new plug in air horn. If new plug not available, use Delco Threadlock Adhesive X-10 on screw threads then adjust voltage, as in step 3). Clear trouble code memory after adjustment.

THROTTLE POSITION SENSOR SPECIFICATIONS

4.3L E4ME TPS Adjustment Screw Location. Scheme 25

AUTOMATIC CHOKE

All engines have nonadjustable chokes.

FUEL PUMP

FUEL PUMP SPECIFICATIONS

1. Federal models with 2.8L and 4.3L engines are equipped with Delco High Energy Ignition (HEI) distributors. California models with 2.8L engines have Delco HEI Electronic Spark Timing (HEI-EST) distributors.
2. California models with 4.3L engines are equipped with Delco HEI-EST distributors with Electronic Spark Control (ESC).

DISTRIBUTOR PICKUP COIL RESISTANCE (OHMS)

IGNITION COIL

COIL RESISTANCE (OHMS) @ 75°F (24°C)

FUEL SYSTEMS

CARBURETORS

BATTERY

BATTERY SPECIFICATIONS @ 0°F (-18°C)

STARTER

All models are equipped with Delco overrunning clutch starters.

STARTER SPECIFICATIONS

ALTERNATOR

All models are equipped with Delco alternators with integral voltage regulator.

ALTERNATOR SPECIFICATIONS

ALTERNATOR REGULATOR

All models are equipped with Delco nonadjustable voltage regulators, integral with alternator.

BELT ADJUSTMENT

BELT ADJUSTMENT (1)

SERVICE INTERVALS

REPLACEMENT INTERVALS

CAPACITIES

FLUID CAPACITIES

SYSTEM REFRIGERANT CAPACITIES