How to Adjust Timing on a Car

Ignition timing refers to the ignition system that allows the spark plug to fire, or ignite, a few degrees before the piston reaches top dead center (TDC) on its compression stroke. In other words, ignition timing is the adjustment of the spark produced by the spark plugs in the ignition system.

When the piston travels to the top of the combustion chamber, the valves close and allow the engine to compress the mixture of air and fuel inside the combustion chamber. The ignition system's job is to ignite that air/fuel mixture to make a controlled explosion to allow the engine to rotate and produce power that can be used to move your vehicle. The ignition timing or spark is measured in the degrees the crankshaft is rotating, bringing the piston to the top of the combustion chamber, or TDC.

If the spark comes before the piston reaches the top of the combustion chamber, also known as advanced timing, the controlled explosion will work against the engine rotating and produce less power. If the spark comes after the piston starts traveling back down the cylinder, known as retarded timing, the pressure created when compressing the air/fuel mixture will dissipate and create a weak explosion, not allowing the engine to produce maximum power.

A good indicator that ignition timing may need to be adjusted is when the engine runs too lean (too much air, not enough fuel in the fuel mixture) or too rich (too much fuel and not enough air in the fuel mixture). These conditions are sometimes shown by the engine backfiring or pinging while accelerating.

Having the correct ignition timing will allow the engine to efficiently produce maximum power. The number of degrees will vary between manufacturers so it is best to check the service manual for your specific vehicle to determine exactly what degree to set your ignition timing.

Part 1 of 3: Locating timing marks

Materials Needed

  • Distributor wrench of the appropriate size
  • Free repair manuals ­ Autozone provides free online repair manuals for certain makes and models Autozone
  • Repair manuals (optional) Chilton

Older vehicles that have a distributor ignition system will have the ability to fine-tune ignition timing. Typically, timing will need to be adjusted due to the normal wear of moving parts in the ignition system. One degree may not be noticeable at idle, but at higher speeds this can cause the vehicle’s ignition system to fire a little early or late, which will decrease overall performance of the engine.

If your vehicle uses a distributorless ignition system such as coil on plug, timing cannot be adjusted as the computer makes these changes on the fly when necessary.

crankshaft pulley and timing cover with arrows pointing out the timing cover marks and crankshaft pulley mark

Step 1: Locate the crankshaft pulley. With the engine off, open the hood and locate the crankshaft pulley.

There will be a mark on the crankshaft pulley along with degree mark(s) on the timing cover.

  • Tip: These marks can be observed while the engine is running by illuminating this area with the timing light to check and adjust ignition timing.

pink clamp clamped around the spark plug wire for the number one cylinder

Step 2: Locate the number one cylinder. Most timing lights will have three clamps.

A positive/red and negative/black clamp is hooked up to the vehicle’s battery and a third clamp also known as the inductive clamp, clips around the number one cylinder’s spark plug wire.

  • Tip: If you do not know which cylinder is #1, consult the factory repair information for the firing order.

hand on distributor as if they were going to rotate it in one direction or the other

Step 3: Loosen the adjusting nut on your distributor. If ignition timing needs to be adjusted, loosen this nut enough to allow the distributor to rotate so timing can be advanced or retarded.

Part 2 of 3: Determining if adjustment is needed

Materials Needed

  • Distributor wrench of the appropriate size
  • Free repair manuals ­ Autozone provides free online repair manuals for certain makes and models Autozone
  • Repair manuals (optional) Chilton
  • Timing light

picture of instrument cluster with a green circle highlighting the temperature gauge showing engine is at normal operating temperature

Step 1: Warm up the engine. Start the engine and allow it to rise to an operating temperature of 195 degrees.

This is indicated with the temperature gauge needle reading in the middle of the gauge.

picture of timing light and its wiring showing where electrical wires are being attached

Step 2: Attach the timing light. Now is a good time to attach your timing light to the battery and number one spark plug and shine the timing light at the crankshaft pulley.

Compare your readings to the manufacturer's specifications in the factory repair manual. If the timing is out of spec, you will need to adjust it in order for the engine to run at maximum performance.

vacuum line being disconnected

  • Tip: If your vehicle has vacuum-assisted ignition timing, disconnect the vacuum line going into the distributor and plug the line with a small bolt to prevent a vacuum leak while the timing is being adjusted.

Part 3 of 3: Performing the adjustment

Materials Needed

  • Distributor wrench of the appropriate size
  • Free repair manuals Autozone provides free online repair manuals for certain makes and models Autozone
  • Repair manuals (optional) Chilton
  • Timing light

Step 1: Loosen the adjusting nut or bolt. Return to the adjusting nut or bolt on the distributor and loosen it enough to allow the distributor to rotate.

service connector with a jumper wire linking the two wires of the connector together with a hand holding the connector

  • Tip: Some vehicles require you to install a jumper wire on an electrical connector to short or break the connection with the vehicle’s computer so timing can be adjusted. If your vehicle has a computer, overlooking this step will prevent the computer from accepting the adjustments.

Step 2: Rotate the distributor. While using the timing light to look at the timing marks on the crank and timing cover, rotate the distributor to make the necessary adjustments.

  • Note: Each vehicle may vary, but a general rule of thumb is, if the rotor inside the distributor spins clockwise with the engine running, rotating the distributor counterclockwise will advance ignition timing. Rotating the distributor clockwise will perform the opposite and retard ignition timing. Use a steady gloved hand to slightly rotate the distributor in either direction until the timing is within the manufacturer's specifications.

Step 3: Tighten the adjusting nut. Once timing has been set at idle, tighten the adjusting nut on the distributor.

Have a friend blip the throttle. This involves quickly pushing on the accelerator pedal to increase engine RPM and then releasing it, allowing the engine to fall back to idle, therefore confirming the timing is set to specifications.

Congratulations! You have just set your own ignition timing. In some cases ignition timing will be out of spec due to a stretched timing chain or belt. If, after setting timing, the vehicle is showing symptoms of untimed, it is recommended you consult a certified mechanic, such as one from YourMechanic, for further diagnostics. These professional technicians can set your ignition timing for you, as well as make sure your spark plugs are up to date.


Next Step

Schedule Oil Change

The most popular service booked by readers of this article is Oil Change. YourMechanic’s technicians bring the dealership to you by performing this job at your home or office 7-days a week between 7AM-9PM. We currently cover over 2,000 cities and have 100k+ 5-star reviews... LEARN MORE

SEE PRICING & SCHEDULING

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Recent Oil Change reviews

Excellent Rating

(21,699)

Rating Summary
20,382
845
179
87
206
20,382
845
179
87
206

Matthew

33 years of experience
991 reviews
Matthew
33 years of experience
Volkswagen Passat - Oil Change - Hampton, Virginia
Matt always does a great job. Very professional. I look forward to my next appointment.... A++++++
Ford Expedition - Oil Change - Hampton, Virginia
I am so please to have Matt work on my vehicle, he is very friendly and personable, and always does a great job.

Greg

22 years of experience
37 reviews
Greg
22 years of experience
Audi A3 - Oil Change - Queen Creek, Arizona
Job well done! Greg was on time and professional. He treated my vehicle with care. He completed the job smoothly and so far so good. First time using Your mechanic and it was a pleasant experience. I will be looking into them again. Thanks Greg!
Ford Explorer - Oil Change - Scottsdale, Arizona
Greg was very friendly and professional. Communication was great, he let me know what he was doing. He went above and beyond to make sure everything was running smoothly. I would 100% recommend Greg!

LAVELL

27 years of experience
93 reviews
LAVELL
27 years of experience
Buick Encore - Oil Change - Oakland, California
Another home run! Really appreciate the flexibility regarding my service appointment. Due to my work schedule I desperately needed a late appointment. So grateful my car is receiving top shelf professional service. Replaced a oil pan drain plug that was seriously damaged and stripped by a competitor that will NEVER get my business again! All services were quickly completed. Thank you so much for another great experience with my.... Your Mechanic Lavell 5 ⭐️ Service consistently.

Brian

23 years of experience
483 reviews
Brian
23 years of experience
Porsche 911 - Oil Change - Ponte Vedra Beach, Florida
Brian is extremely knowledgeable and very personable and has taken very good care on my 911. I would recommend Brian to any one who has mechanical car challenges. I would recommend Brian to all My friends and family

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

Related articles

How Often Should the Ignition System Be Inspected?
Your Your ignition system is a critical part of both your car and daily driving experience. If it isn't working correctly, you could experience anything from poor engine operation to engine stall or failure to start. It’s critical that you...
How Does a Distributor Work?
In In older cars, a distributor is one of the central parts of the ignition system. Since the early 1990's, many automakers have moved to using ignition systems without distributors. Though the number of cars with distributors has declined over...
What Is the Difference Between Conventional, Electronic and Distributor-less Ignition Systems?
If If you’re like many people, you know that when you turn the key in your ignition, the engine cranks and you’re able to drive your car. However, you might not know how that ignition system works. For that matter,...

Related questions

Whan engine is warm, it shuts off and won't restart

Hello there, thank you for asking about your 1985 Dodge Ramcharger. We must determine what is going on when the engine is warm that causes the no start. The proper fuel pressure and ignition signals must be present or it...

Timing chain too loose

Hello. The rattling sound that you are hearing could be coming from several different areas of the engine. Your drive belt pulley could be bad, a compressor clutch could be loose, or the alternator pulley or timing chain could be...

Jeep won't turn over after sitting for 8 hours 2001 Jeep Cherokee

Hello - I would first check the battery cables and ground straps for corrosion, or other poor-connectivity problems. A strong battery can be hampered by poor connections, which will sometimes finally pass current. A failing starter solenoid (burned contacts) will...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com