Can You Set Ignition Timing Without A Timing Light?

Have you ever wanted to adjust the ignition timing of your car’s engine? Only to be stumped by the lack of the timing light? The skill to set ignition timing without a timing light is valuable for a DIY car enthusiast. Advancing the ignition timing by a minuscule amount increases the engine’s horsepower. Consequently, it is quite an attraction for people looking to upgrade their car’s performance.

timing belt controls the ignition timing

All the moving parts in the engine require precise timing for the smooth operation of the vehicle. A timing belt provides this precision. For a spark-ignition engine, the timing belt also controls the spark plugs. If the spark plug does not go off at the right time, you can face multiple problems with your engine.

What Is Ignition Timing?

To understand that, we must first learn how engines work. Four-stroke engines are the most commonly used type of engine in the commercial car market. They work in 4 strokes, covering two complete revolutions of the crankshaft:

  1. Suction Stroke: The fuel-air mixture is injected into the engine cylinder as the piston moves down.
  2. Compression Stroke: The piston, now moving upwards, compresses the mixture to the correct pressure. For spark-ignition engines, near the end of the compression stroke, the spark plug ignites the mix. Ignition timing is the moment the spark takes place.
    four stroke engine cycle
  3. Expansion/Power Stroke: The expanding gases from the combustion push the piston down during the power stroke.
  4. Exhaust Stroke: The burnt gases are expelled from the engine when the pistons move back upwards.

For most cars new from the factory, the ignition timing comes adjusted for the highest fuel economy. In performance cars, though, it will be fixed to get more power out of the engine.

In the quest for a little more horsepower, some car owners advance the ignition timing by about 5 degrees of crank rotation. We also have an article on increasing the horsepower of a carburetted engine. If you are interested in doing so, you can go check it out.

What Happens If The Ignition Timing Is Off?

If the timing of your ignition system is off, the engine’s performance will be affected. One must pay attention to the warning signs to make required adjustments. If not done, the car needs looking at sooner rather than later. As you drive your vehicle, the ignition timing changes gradually.

Issues can crop up even if the timing is only slightly off, whether advanced or retarded. Some things to look out for:

  • Engine knocking: Knocking occurs when the fuel-air mixture ignites too early in the cylinder. The combusted gas applies pressure against pistons still in the compression stroke. Loud pinging sounds will arise from the engine.
  • Decreased fuel economy: The timing of the spark is critical during the ignition process. Ignition at the wrong time knocks the combustion process off. Consequently, your engine uses more fuel to compensate for diminishing power.
  • Overheating: Premature ignition in the combustion process increases heat generation. As a result, damage may occur in different parts of the engine.overheating of the engine caused by improper ignition timing
  • Low Power: Exessive retardation of the ignition timing means the spark plug will fire too late in the power stroke. It decreases your engine’s power. As a result, acceleration will be sluggish.
  • Hard Starting: Wrongly set ignition timing can make starting your car problematic.
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The above are some phenomena to look out for when it comes to ignition timing and performance. Noticing them in advance will allow proactive maintenance of your vehicle. Another point is that the optimal ignition timing varies by altitude, depending on the air density. What works in the plains will not be correct for the hills.

Types Of Ignition

Before we change the ignition timing, we need to understand the kind of ignition your car uses. Each type requires a different tweaking technique.

1. Breaker Point Ignition

This kind is the oldest type of ignition and does not find use in newer cars. However, older vehicles still have this technology. The distinguishing feature of such ignition is the breaker point in the distributor. It connects to the ground terminal through a lever. A cam attached to the distributor shaft rotates in time with the engine, connecting and disconnecting the breaker point as required.

With continued usage, these breaker points wear out and throw the ignition timing off-kilter. As such, the car needs a yearly tune-up and the replacement of the breaker points when that happens.

2. Electronic Ignition

Distributor based electronic ignition is the commonplace ignition technology found in today’s cars. When you replace the distributor shaft or a loose timing belt, you need to adjust the timing for the proper function of the engine.

With distributor-type ignitions, it is a simple matter to set the ignition timing by hand. So, you can achieve it using a few mechanic’s tools.

3. Computer-controlled Ignition

The car’s powertrain control module (PCM) sets the timing in distributor-less electronic plugs and coil-over-plug ignition mechanisms. Computer-controlled ignitions find application in the newest cars today. So, adjusting the timing in these cars requires reprogramming the PCM. An assortment of programming chipsets is available on the market that allows you to change these settings on your PCM.

power control module; can be reprogrammed without a timing light, of course

How To Set Ignition Timing Without A Timing Light

If you don’t have a timing light, there is no need to give up hope. There exist a few tricks to obtain optimal ignition timing without resorting to a timing light. However, these methods require a bit of ingenuity and effort.

1. A Static Timing

You can set the optimal ignition timing by looking at the spark plug while turning the degree wheel or pulley.

2. Electronic Timing Probe

Cars with an electronic ignition come equipped with a magnetic sensor on the ignition apparatus. The sensor attaches to a tube with the front pulley.

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So, to set the timing, check for a timing degree on the digital readout. Match the timing sensor probe to this mark.

3. Timing By Ear

The first step to set ignition timing without a timing light is finding out rotating the distributor in which direction would advance the timing. Locate the vacuum advance module, and then note which way it attaches to the distributor body. Look at the following picture to understand this.

distributor with the vacuum advance module pointing in the anticlockwise direction

Recall that when the vacuum applies to the module, it pulls on the timing plate inside the distributor to bring forward the timing. You will have to rotate the distributor in that direction for advancing the ignition timing.

Now, how to set ignition timing by ear. First, warm the engine up to its typical operating temperature. Then, remove the vacuum advance hose from the distributor and plug it. If the car’s engine operates without surging or pinging, you can advance the timing. Keeping the engine off, bring forward the distributor a couple of degrees. Once done, start the engine. If it starts okay, repeat the process.

Eventually, you will reach a point where either the starter or the engine lugs or struggles during starting. It indicates that you have gone too far. Back up the timing just enough so that the starter spins the engine freely again. After that, you need to tighten the hold-down bolt and reconnect the vacuum hose.

Next, your car requires a test drive for the rest of the procedure. Drive at a few different speeds, and accelerate hard at a couple of points. If you hear pinging, retard the timing by a small amount. Also, try driving steadily at about 40 to 50 mph at part throttle. If you note a slight surging in the engine, retard the timing a little more.

Your ignition timing is now as close to optimal as possible.

4. With A Vacuum Guage

It is not as precise a method as a timing light. But in an emergency, it works well enough. Connect a vacuum gauge to any non-ported vacuum source behind the throttle plate.

vacuum gauge to set ignition timing without a timing light

After that, set the timing to produce 18–20 inches of mercury at idling conditions. Hence, a higher vacuum indicates an excessive advancement of ignition timing; a lower vacuum is a sign of retardation.

A DIY Timing Light

How do you make a homemade timing light? You can build a timing light using a few electronic components. Those components are an electronic breadboard, some resistors, diodes, a MOSFET, a capacitor, small LED bulbs and connecting wires with alligator clips. If you study the diagram given below, you can understand the schematic for building a timing light.

homemade timing light circuit diagram

You can see the complete device in the video, and it works pretty well. A DIY timing light can be used the same way as a store-bought model.


As you have seen, a timing light is not always necessary for timing the engine. The crucial point is to know which type of ignition your car has. If your vehicle had incorrect timing before, you now know how to set ignition timing without a timing light.

On the other hand, if you are unsure about the DIY approach, consult a professional mechanic. On a more regular basis, you can save yourself undue stress if you keep your vehicle in good working conditions.

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