How to Adjust the Timing on Chevrolet Carsby Contributing WriterUpdated June 12, 2017
The Chevrolet car. Proper ignition timing plays a crucial role in engine performance. If the timing is off, the engine may overheat, lose power, stall, backfire, stop running or fail to start. Permanent engine damage can occur if the pistons strike the valves repeatedly. If the timing belt or chain on the vehicle is functioning correctly, you must simply reset the timing on the vehicle to restore the engine's performance. Set the ignition timing under the hood near the crankshaft pulley.
Under The Hood:
- How to Adjust the Timing on a 1988 Chevy S-10 2.8L V6
- How to Adjust the Timing on a 1997 Chevy S10
- How to Adjust the Timing on a '92 Chevy 4.3
- How to Adjust the Timing in a Geo Metro
- How to Adjust the Timing in a Geo Tracker
Locate the timing mark pointer plate beside the crankshaft pulley. The "0" mark represents top dead center. The pointer plate will be marked in either one or two-degree increments and should have the timing mark for your 2.8L V6 engine noted. If not, count back from the "0" mark the correct number of degrees before top dead center, as noted on the VECI label under the hood, and mark the plate with chalk.
Find the notch on the crankshaft pulley. Mark it with chalk so it will be visible under the timing light.
Ensure the ignition is off. Connect the pick-up lead of the timing light to the number one spark plug wire, located on the front cylinder on the passenger side of the vehicle. Do not pierce the wire or attempt to insert the wire between the boot and the wire. Connect the timing light power leads according to the manufacturer's directions.
Start the engine. Aim the timing light at the timing mark by the crankshaft pulley and note which timing mark the notch on the pulley is lining up with. If the notch is not lined up with the correct mark, loosen the distributor hold-down bolt and rotate the distributor until the notch is lined up with the correct timing mark.
Tighten the hold-down bolt and recheck the timing. Turn off the engine and disconnect the timing light. Reconnect the number one spark plug wire, if removed.
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Start the Chevy by turning on the ignition. Allow your truck to run until the engine reaches operating temperature. Leave it in Park and rev the engine speed up to 3,000 rpm two or three times by pressing on the gas pedal. Turn off the ignition.
Open the hood of the S10. Remove the yellow cap from the ignition timing adjustment on the wiring harness. Locate this in the rear of the engine. Connect all pins on the white, green, and brown wires using a small jumper.
Connect cables of the timing light to the main battery of the S10. Clip the timing light cable to the first spark plug wire at the front of the engine in the S10. Restart the ignition.
Loosen the nuts that attach the distributor cap to the top of the distributor using a 12 mm wrench. Rotate the S10 distributor clockwise until you can line up the pointer on the timing belt with the notch on the crankshaft pulley. Disconnect the jumper wire and timing light from the engine of the Chevy S10.
Drive the S10 to verify that the timing is properly adjusted.
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Look into the engine block for the metal timing scale, a component measuring 4 inches long sitting just above the crankshaft pulley (the bottom pulley). You will probably need to remove the road grime to make the numbers legible. A can of aerosol brake cleaner or penetrating oil and a shop towel will take care of the problem.
Locate the dampener pulley positioned directly behind the crankshaft pulley. You will find a deep groove cut into the dampener pulley. Highlight the groove with your chalk or paint marker to make it easy to see in future steps.
Move to the passenger-side firewall, and find the bypass connectors behind the relay panel cover. Remove the three plastic nuts that hold the cover in place. The bypass connector itself is a tan wire with a black stripe that divides into two sections. Unplug the connector to put the vehicle's computer into "base timing" mode and allow it to receive an accurate signal from the distributor.
Find the distributor at the rear of the engine. Loosen the lock-down bolt underneath the distributor using a distributor wrench. Loosen it just enough that you can turn it.
Connect your timing light to the vehicle's battery. As with battery cables, the red clip connects to the positive side, and the black to the negative. The light's inductive pickup wire connects to the outside of the No. 1 spark plug wire - -the front one on the driver's side. Try to get as close to the base of the wire as you can, which will produce the most accurate reading.
Engage your emergency brake. Put your transmission in neutral if you have a manual, or park if you have an automatic. Start your vehicle, and allow it to warm up for about five minutes while idling.
Point the timing light to the timing scale with the truck idling. The light will flash and illuminate the numbers on the scale and the dampener groove you highlighted earlier. This flash represents the exact time that spark plug wire received its signal from the distributor.
Adjust the distributor gently by turning it until the groove on the dampener pulley aligns with "0" on the scale.
Retighten the distributor, and recheck the timing. If it is still correct, turn the vehicle off and disconnect the timing light. Reconnect the bypass connector, and attach the cover.
Items you will need
Chalk or white paint marker
Start the Geo Metro engine and allow it to idle until it reaches normal operating temperature. Turn the engine off, leaving the ignition in the "On" position for five seconds, then restart the car. Run the engine at 2,000 RPM for 5 minutes then let it idle.
Turn off all accessories such as the radio, air conditioning and lights. Place the transmission in "Park" or "Neutral" and set the parking brake.
Connect the tachometer to the negative side of the ignition coil. Attach the timing light to the battery and then into the number one ignition wire on the front or far right side of the engine.
Remove the cap from the diagnostic connector next to the ignition coil and jump the lower two terminals with a number 4 terminal connector. Aim the timing light at the timing marks on the crankshaft pulley.
Loosen the distributor mounting bolts and turn the distributor until the crankshaft timing light matches the center mark in the timing gun. Tighten the distributor mounting bolts and recheck the timing. Remove the number 4 connector and replace the cap.
Items you will need
Number 4 terminal connector
Start the engine and allow it to reach normal operating temperature. Turn the ignition off, locate the test switch module behind the right hand headlight assembly, and remove the cover. Use a small gauge wire to jump terminal "4" and "5," located at the bottom left and middle terminals.
Connect the timing light to the battery if necessary and then to the number one ignition wire located at the far, driver's side of the engine. Clean off the crank pulley at the front of the engine to expose the timing marks. Start the Geo Tracker and let it idle for 2 minutes.
Point the timing light at the crank pulley and determine the amount of adjustment needed. Loosen the distributor flange bolts and rotate the distributor slowly until the crank pulley mark matches the middle line on the timing light.
Tighten the distributor flange bolts and recheck the timing. Make any additional adjustments and turn off the engine. Remove the timing light and jumper wire. Reconnect the number one ignition wire and replace the cap on the test switch module.
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