A Crash Course on How to Use a Timing Light

A lot of dedicated car owners can be meticulous when it comes to tinkering with their engines. Instead of heading down to the nearest repair shop, some of these drivers prefer doing the dirty work in the comfort of their garage.

Aside from handling tasks like getting an oil change, another thing dedicated DIYers do is adjust their engine’s ignition timing.

What Does a Timing Light Do?

A digital timing light is a diagnostic tool that’s used to check an engine’s ignition timing. Timing lights are usually used on classic carbureted rides, but they’re also used on some modern engines with a distributor and any vehicle with an adjustable ignition timing.

A timing light usually has a red and black cable that’s attached to the positive and negative battery terminals and an inductive clamp that’s attached to the No. 1 spark plug or its wire.

The Importance of Adjusting Ignition Timing

Adjusting the ignition timing helps your vehicle operate at maximum efficiency. Advancing the ignition timing can maximize horsepower, improve gas mileage, and help produce a smoother idle.

Types of Timing Lights

Timing lights come in a variety of shapes and sizes. You’ll find some that look like bells and pens as well as ray-gun-shaped ones.

Timing lights can look a bit different from one another, but they all generally work the same way. Here are some of the most common types of timing lights.

Standard Timing Light

A standard or inductive timing light is typically used on two and four-cycle motors. This type has a non-adjustable Xenon light.

An inductive timing light usually has buttons or a knob to adjust the light and reveal the timing at various RPMs.

Some inductive timing lights also come with a tachometer and dwell meter that helps you monitor the time it takes for the system to charge the ignition coil.

Battery-Powered Timing Light

A battery-powered timing light is ideal for race cars and other unique vehicles that don’t have their batteries and leads in the engine compartment.

Unlike the conventional timing light, this type only has two wires instead of three.

MSD-Compatible Timing Light

A vehicle with a multi-spark distribution system (MSD) will need an MSD-compatible timing light. A conventional timing light won’t be able to provide accurate readings because it’ll only get confused if it picks up more than one spark.

How Does a Timing Light Work?

The operation of a timing light is based on the stroboscopic effect, which is a phenomenon that brands motion as an artifact.

According to this phenomenon, the human brain interprets motion as a succession of discrete images stitched together for temporal continuity.

Upon activating the timing light, a beam of light should flash each time the No. 1 spark plug fires.

When aimed properly, the digital timing light should be able to indicate the position of the No. 1 piston in its up-and-down travel every time the spark fires.

How to Use a Timing Light

Here’s a step-by-step guide on how to use a timing light.

Step 1: Make sure that the engine is at operating temperature before turning it off.

Step 2: Hook up the device’s red cable to the battery’s positive terminal and the black one to the negative terminal.

Step 3: Attach the inductive clamp to the No. 1 cylinder. The timing light should be able to pick up a signal. Also, make sure the number one spark plug wire and inductive pickup aren’t touching other plug wires to avoid picking up misreadings.

Step 4: Look up the procedure for ignition timing. Even though there is a vacuum hose connected to the distributor, vacuum advance is not always disconnected. Sometimes, there are two vacuum hoses to the distributor. Sometimes there is no vacuum line, but you might have to disconnect an electrical connector.

Step 5: Loosen the distributor enough to be able to rotate it freely.

Step 6: Turn on the engine.

Step 7: Use the timing light to isolate the timing mark on the crankshaft pulley.

Step 8: As the timing light flashes, it should display the degree of timing. Then, find the top dead center mark.

Step 9: Input the advanced settings on the timing light and rotate the distributor until you see the top dead center again.

Step 10: Use a wrench to tighten the distributor.

Ignition Timing: The Basics

The firing of the spark plug in relation to the position of the piston is referred to as ignition timing. Spark timing depends on engine speed and must be done in advance as the engine rotates faster.

On most vehicles, the powertrain control module (PCM) determines the timing advance. If the proper ignition timing is observed, the air-fuel mixture will be completely burned when the piston reaches 10 degrees after the top dead center.

In most cases, mechanical wear on parts like the timing chain, distributor gear, and camshaft drive gear can alter the ignition timing.

Ignition timing specifications are usually on the vehicle’s underhood, specifically the emission control information decal. The same information can also be found in the vehicle’s service manual.

The Verdict: Do You Really Need a Timing Light?

Having a timing light isn’t exactly a necessity. Those who have and know how to use this device are usually looking for cost-effective solutions to keep their vehicles in tip-top shape.

Operating a timing light might seem like a simple process, but it does require advanced auto repair knowledge.

Adjusting the ignition timing without the right set of tools and know-how can do more harm than good. If you’re not well-versed in auto repair, a trip to a certified auto repair shop is your best bet at getting a proper adjustment.

How Much Does a Timing Light Cost?

A timing light can cost anywhere between $100 to $500, depending on factors like the brand and your vehicle’s specifications. Note that some vehicles won’t respond well to conventional timing lights and might require a different variant.

Where to Get a Timing Light

You’ll find a lot of timing lights online, including shops like CarParts.com.

CarParts.com has a great selection of aftermarket timing lights that come with a low-price guarantee to help you get the best value for your money. Order now, and you can get your timing light delivered to your doorstep in as fast as two business days.