How to Use a Timing Light?

Imagine yourself going out for a nice drive when suddenly you hear constant shudders and knocks from your engine. Now, you can either take your car to the nearest repair shop and spend some extra cash or just get yourself a timing light.

These nifty devices enable you to sync the timing of the sparks that ignite your car’s fuel. Well-adjusted timing aids the engine’s ability to perform at its peak.

Before you run off to the store to buy yourself one, it’s important that you know how to use a timing light first. Below, we have laid down some basic steps you will need to know before using a timing light.

Things to Remember

Here are some tips that you should follow.

  • Gather All Your Tools First

When working under the hood, it’s always wise to get your toolbox out before you begin turning screws. This will give you the flexibility of having your required tools at your disposal whenever they are required. The most basic tool you will need is a wrench.

So, if you don’t have a toolbox around, make sure you get a combination wrench, which will allow you to loosen all sorts of nuts and bolts in the future.

  • Identify the Number 1 Spark Plug Wire

The timing light requires you to clamp its signal wire to the Number 1 spark plug wire in your car. And the Number 1 spark plug wire can be difficult to identify, depending on your car model. We suggest that you look into online forums and service manuals for your vehicle model in order to identify the Number 1 spark plug.

  • Find the Proper Timing Specification

Using the timing light gives you the flexibility to adjust the timing of the ignition. But in order to adjust the timing, you will first need to know what the ideal timing specifications are for your vehicle.

Vehicle Emission Control Information Labels located on the underside of the hood and service manuals for your vehicle should give you a proper idea.

How to Use a Timing Light?

After you have done your homework on the spark plug wires and specifications of your vehicle model, you can finally start using the timing light.

  • Precautionary Measures

Before you begin, it is always a good practice to read the instruction manual of your timing light thoroughly.

You will want to make sure the battery terminals are clean. This will ensure a smooth flow of electricity resulting in accurate readings. Be sure to turn off the engine and keep your key out of the ignition.

  • Setting up the Timing Light

All timing lights will have a red clip, a black clip, and the third clip with thick insulation. You will begin by attaching the red clip to the positive terminal of your car using the clamps.

Similarly, the black clip clamps on to the negative terminal. The third clip will be clamped directly on the Number 1 spark plug wire.

You should know that some of the timing lights require you to attach its spark signal pick-up wire to the tip of the Number 1 spark plug. So before you attach the spark signal pick-up wire, refer back to the manual.

Much like a doctor using a stethoscope for hearing your pulse, the spark signal pick-up wire will detect the rush of electric jolts with each firing of the spark plug.

  • Pulling the Timing Light Trigger

With the timing light connected, you will now need to start the car and keep it idle. Locate the timing marks on your engine, which should be located on the crankshaft pulley or harmonic balancer (depending on your model).

If you’re having trouble finding the timing marks, refer back to your vehicle’s manual.

Now that the engine is running and the timing light is connected, you will point it at the timing marks and press the trigger. The light will begin to pulse, creating a strobe effect to highlight the timing for your vehicle.

  • Reading the Timing Light

On the screen of the timing light, you will notice the readings in degrees. This might lead you to wonder why degrees are being used.

It’s simple, the Top Dead Center (TDC) is considered to be the highest point each piston reaches inside the cylinder. With the use of a timing light, you will only need the TDC on the Number 1 piston on the compression stroke.

The distance from the firing of the spark plug to the end of the piston’s stroke is referred to as the ignition timing, which is measured in degrees before or after the TDC on the crankshaft pulley or the harmonic balancer.

Say, for example, your spark plug fires exactly at the top dead center. This means the piston is at its peak inside the cylinder, and the balancer mark will read 0. Thus, a timing measurement of 0 degrees will be shown on your timing light screen.

Now, if the spark plug fires before the top dead center and the balancer mark reads 5, this would be read as 5 degrees before TDC.

  • Adjusting the Timing 

With the reading on your screen, you will now begin to adjust the distributor clamp to correct the timing. At the base of the vehicle’s distributor shaft, you will notice a hold-down clamp.

Using a wrench, the distributor clamp needs to be loosened to enable you to rotate the distributor according to your preference.

Depending on whether your distributor spins clockwise or anti-clockwise, turning the distributor in one direction will retard the spark, and the other direction will advance it.

To get a proper understanding of the turning mechanism, we advise you to rotate the distributor in one direction and check again with the timing light to see where the pointer stands.

Don’t worry if you don’t get it right the first time, this step can be quite tricky. However, repeated trial and error will eventually give you the right timing.

  • Setting Your Preferred Time

Once you have adjusted the distributor to your desired setting, you will now begin to tighten the fastener for the distributor hold-down clamp. Be very careful while doing this as moving the distributor might make a mess of your timings.

After you’ve successfully tightened the distributor clamp, double-check the timing with your timing light. If the reading isn’t what you wanted, then you probably need to re-adjust it.

  • Disconnecting the Timing Light

With your sparks flying the way you want them to, now you can begin to disconnect the timing light.

Turn off the engine and pull out your keys from the ignition before you begin to take out the clamps of the timing light.

When you’ve managed to disconnect the timing light, give yourself a nice pat on the back to reward your patience and hard work. Oh, but you might want to wash your hands first.


We should inform you that the above points are very general instructions on how to use a timing light.

What you see under your hood depends greatly on the model of your vehicle and also the timing light. Following the service manuals of your vehicle would give you a better edge in using the timing light.

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