How to Adjust the Timing on Cars

by Contributing Writer; Updated June 12, 2017

The Mazda car and identical Mazda car B-Series use a high-voltage electronic ignition system. You must be careful not to cross or short any wires or connectors to avoid serious damage to the components. The system of sensors in most models is sufficient to manage the ignition timing without adjustment. The initial timing adjustment is accomplished by rotating the distributor while the engine is running. Care must be taken to secure any loose clothing from becoming tangled in the moving parts. Ignition timing must change as engine speed increases. On the Mazda car this is accomplished by the vehicle's computer using the Hall Effect of resistance and conductivity.

Under The Hood:

 How to Adjust the Timing on a 4.3L

Locate the adjusting timing scale above the crankshaft pulley on the front and bottom of the engine. Wipe off dirt or grease from the timing scale marks with a shop rag and trace the marks with a white marker to make the numbers and dashes more visible during timing adjustment.

Locate the small groove mark on the crankshaft pulley. You will find it on the edge of the pulley as it rotates right in front of the timing scale. You might need to set your transmission to "Neutral" and rotate the crankshaft pulley clockwise with a breaker bar and socket to find this mark. Once you find it, trace it with the white marker to make it more visible during the timing adjustment.

Drive your vehicle for about 20 minutes on the highway, to make sure the engine reaches operating temperature, and go back to your driveway. Turn off the engine, set the parking brake and block the front and rear wheels with four wooden blocks.

Open the hood and connect a timing light to the engine. The two cables with the alligator clip terminals on the timing light hook up to the battery. The red clip connects to the positive (+) or red battery cable and the black clip connects to the ground (black) battery cable.

Connect the third cable on the timing light to the spark plug wire on the No. 1 cylinder. This third cable on the timing light has a clip that fully encloses the spark plug wire. The No. 1 cylinder is the closest to the front of the engine, the side where the drive or serpentine belt is located.

Unplug the thin rubber hose from the distributor advance. The advance is the metal, spinning top-shaped component on one side of the distributor. The distributor is where all the spark plug wires connect. Plug the thin hose opening with a screw or golf tee. If your 4.3L model does not come equipped with this distributor advance, look for the electronic spark timing (EST) connector, a small plastic cylinder with a single wire on each side. You may find it under the floor carpet on the passenger's side or near the brake booster inside the engine compartment on the driver's side or passenger side.

Find the emission label on the engine compartment, a small square label with tuneup information for your specific vehicle, and find the required engine speed or RPM for the engine during timing adjustment and the number indicating the correct timing for your specific vehicle model. Otherwise, look up the information in your vehicle service manual or call your local dealer.

Make sure the timing light wires are out of the way of the cooling fan, drive belts or other moving parts inside the engine compartment. Start the engine and have an assistant slightly step on the accelerator, if necessary, to speed up the engine to the required RPM.

Activate and aim the timing light at the timing marks on the crankshaft pulley. The strobe light will let you see the timing mark on the crankshaft pulley pointing to one of the numbers on the timing scale above the pulley. If the mark is pointing to the incorrect number on the scale, go to the next step. Otherwise, go to Step 11.

Loosen the bolt holding the distributor base to the engine using a wrench. Ask an assistant to grab the distributor body and slightly turn the distributor left or right, so the mark on the crankshaft pulley moves to the correct number on the timing scale. Tighten the distributor-mounting bolt and double check the pulley mark is still pointing to the correct number on the scale.

Shut off the engine and disconnect the timing light. Connect the distributor advance or EST electrical connector. Close the hood and remove the four wooden blocks from the wheels.

Items you will need

  • Shop rag

  • White marker

  • Breaker bar, if necessary

  • Socket, if necessary

  • 4 wooden blocks

  • Timing light

  • Screw or golf tee, if necessary

  • Assistant

 How to Adjust the Timing on a Dodge 360

Consult your owners manuals for the correct timing setting for your Dodge vehicle. Additionally, timing information may be located on a plate on the sill of the vehicle's grill, under the hood.

Locate the number one spark plug wire. This usually is the first spark plug wire located on the right side of the engine as you face the vehicle. Refer to a service manual if in doubt.

Attach the inductive clamp of the timing light to the number one spark plug wire. Connect the negative (black) and positive (red) leads of the timing light to the respective negative and positive battery terminals.

Loosen the hold-down bolt at the base of the distributor with the wrench. Half a turn is sufficient as you are just loosening the bolt enough so the distributor will rotate.

Start the engine and point the timing light at the timing plate mounted above the flywheel. Pull the trigger on the timing light. The light will flash each time the number one spark plug fires, revealing the location of the timing mark on the flywheel in relationship to the marked numbered lines on the timing plate.

Rotate the distributor slightly in one direction while watching the mark on the flywheel move against the marks on the timing plate. If the mark on the flywheel move in the wrong way, rotate the distributor in the opposite direction. Stop turning the distributor when the mark on the flywheel is lined up with the correct number on the timing plate.

Tighten the hold-down bolt at the base of the distributor. Check the timing again as the setting will change if the distributor moves as the bolt is being tightened.

Items you will need

  • Inductive timing light

  • Box end wrench

 How to Adjust the Timing in a Dodge Ram

Start the engine and allow it to reach normal operating temperature. If the vehicle is at 3,900 feet or more above sea level, open the hood and look for the pressure sensor electrical connector, if equipped. It's located across from the distributor, mounted on the fender. Disconnect the sensor.

Stop the engine and connect the timing light to the battery if necessary and then to the number one ignition wire located at the front driver's side on six cylinder engines and at the back passenger's side on eight cylinder models.

Turn the engine on and allow it to idle for 2 minutes. Point the timing light at the crankshaft pulley and determine the amount of adjustment needed.

Loosen the distributor mounting bolts and rotate the distributor until the crankshaft timing mark matches the middle line on the timing light. Tighten the distributor mounting bolts.

Check the timing again and then turn off the engine. Remove the timing light, reconnecting both the number one ignition wire and the pressure sensor electrical connector, if necessary.

Items you will need

  • Timing light

  • Wrenches

 How to Adjust the Timing on a Ford Ranger

Set the parking brake and place chocks behind the rear wheels. Place the shift lever in neutral, or park for an automatic. Turn off the air conditioner and heater.

Connect the inductive timing light to the number-one cylinder spark plug wire. This is the front cylinder on the passenger side. Loosen the hold-down bolt on the distributor, located at the back of the engine, only enough for it to move with some effort. Disconnect the spark output connector, normally located astride the pink wire going to the distributor.

Clean the timing marks on the crankshaft pulley and the plate attached to the front of the engine. Use the paint pen to highlight the marks if necessary. Start the engine and warm it up to operating temperature.

At idle speed, use the induction timing light to observe the timing indicated by the marks. If it is not reading 10° Before Top Dead Center, rotate the distributor a little at a time until the mark on the crankshaft is aligned with the 10° BTDC mark on the plate. When the reading is correct, tighten the distributor hold down bolt and check the reading again. Continue this procedure until the adjustment holds at the 10° mark.

Reconnect the spark output plug. Increase engine speed while observing the timing marks. The position of the marks should change as the engine speed increases to indicate a properly functioning advance circuit. If there is no change, refer the vehicle to a professional for assistance.

Items you will need

  • Basic automotive service tool set

  • Timing light with inductive pickup

  • Wheel chocks

  • White or yellow paint pen (optional) to highlight timing marks

 How to Adjust the Timing in a Ford Explorer

Locate and download the version update PDF file from the authorized Ford distributor website. Identify the version to upload and connect the scan tool to the computer. Verify the battery has a full charge or connect it to a reliable battery charger.

Connect the scan tool to the OBD II connector located under the steering wheel and turn the ignition on without starting the engine. Turn off any accessories such as the radio and lights.

Turn on the scan tool and wait for the automatic connection confirmation message to appear. Follow the instructions on the computer screen, answer any questions that pertain to your vehicle including keying in the vehicle identification number or VIN located at the top of the driver's side dash and start the data transfer. Maintaining a solid Internet connection is vital throughout the process, which makes a wireless connection undesirable for this project.

Wait for the successful transfer message to appear on the computer screen. The data transfer can take up to 90 minutes depending on file size and connection speed.

Shut off the ignition and remove the scan tool from the OBD II connector. Start the car and let it idle for 5 minutes. It's normal for the engine to run rough for several hours of driving as the on-board computer adjusts to the new fuel and air configuration.

Items you will need

  • Scan tool

 How to Adjust the Timing in a 1993 Toyota Camry

Warm the engine to normal operating temperature. Turn off the engine. Jumper the terminals labeled "T" and E1 in the diagnostic connector using an unfolded paper clip. The diagnostic connector is a small rectangular box located in the driver side of the engine compartment near the ignition coil.

Attach a timing light to the battery terminals and the number one spark plug wire. In the 1993 Camry the number one spark plug wire is the closest to the passenger side fender. Start the engine.

Point the timing light at the timing marks on the front of the engine's timing cover and note the position of the notch on the crankshaft pulley below it. Loosen the 12mm distributor nuts using a wrench. Rotate the distributor to set timing at 10 degrees BTDC by lining up the 10 degrees mark with the notch on the pulley.

Tighten the distributor nuts and turn off the engine. Remove the timing light and paper clip before test driving.

Items you will need

  • Timing light

  • Wrench set

 How to Adjust the Timing on My 1997 GMC Yukon

Start your 1997 GMC Yukon and allow the engine to run till operating temp is indicated on the temperature gauge on the dash. Turn off the engine and leave the ignition key in the off position.

Disconnect the timing connector located on the main wiring harness. The main wiring harness in the 1997 Yukon runs behind the engine, along the firewall, in the rear of the engine compartment. The timing connector is a small single wire connector attached to a tan wire with a black stripe on it.

Attach the timing light to the battery terminals. Clip the red power wire to the positive battery terminal and the black ground wire to the ground terminal on the battery. Open the spark plug wire lead on the timing light and clip it around the front spark plug wire on the driver's side of the engine. Start the engine.

Aim the light at the Yukon's timing marks located above the crankshaft pulley on the front of the engine. The strobe light effect of the timing light will make the crankshaft pulley appear to stop spinning. Note the position of the groove on the back of the pulley in relation to the marks on the timing tab above the pulley.

Loosen the bolt that secures the distributor in the engine, located at the base of the distributor, using a 9/16-inch distributor wrench. Rotate the distributor with you hand while watch in the timing marks on the front of the engine, until the mark on the pulley aligns with the 10-degrees mark on the timing tab. Tighten the distributor bolt.

Turn off engine and disconnect the negative battery cable from the battery using an 8-mm wrench. Reconnect the timing connector and remove timing light from the engine compartment. Reconnect battery cable to the battery after 5 minutes and test drive the Yukon.

Items you will need

  • Timing light

  • Distributor wrench

  • 8 mm wrench

About the Author

This article was written by the It Still Runs team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information. To submit your questions or ideas, or to simply learn more about It Still Runs, contact us.