Buying guide for Best timing lights
In order for your engine to run properly, the spark plugs have to fire at exactly the right moment. That firing is controlled by the ignition timing. Checking and setting the timing correctly isn’t a complicated job for the home mechanic as long as you have an accurate timing light.
If your spark plug timing is off, all kinds of things can go wrong, from difficulty starting, poor acceleration, and an overall drop in performance to backfiring, strange “pinging” noises, and higher gas consumption. All those things add up to excess stress on the engine — and your wallet! The good news is that there are plenty of timing lights to choose from, and something for any budget. The not so good news is that if you’re looking to buy your first timing light, the capabilities and jargon can be a bit confusing.
To help clarify the important timing light features, we’ve put together this comprehensive buying guide. We’ve also included a number of recommendations that showcase the variety of high-quality, great-value tools available.
Key considerations
Ignition timing 101
In a gasoline engine, ignition timing sends an electric current to each spark plug at precise time intervals and in a predetermined sequence (diesel engines don’t have spark plugs). Older vehicles use a distributor that has spark plug cables sprouting out in all directions. As one expert put it, on a V8 engine, it looks a bit like a rubber octopus!
General wear and tear can cause your timing to run out. The timing chain stretches out eventually. Classic and collectors’ vehicles often have points in the distributor that need changing sooner or later. With older vehicles, it could just be because your engine shakes a fair bit! Whatever the cause, things aren’t running as they should.
Assessing the job
The first thing you need to do is establish whether the job can be done. Most motors built since the 1980s have electronic or breakerless ignition. Many motors built since the 1990s have no distributor or spark plug cables. Lifting the hood just presents you with a big lump of featureless plastic. It should probably bear the words “Hands off!” Unless you’ve got a computer, you aren’t going to adjust the timing on that baby.
If you can do the job, there will be a set of visible timing marks somewhere on the motor, most often on the end of the crankshaft pulley. Sometimes they’re on the fan pulley, sometimes the flywheel, and occasionally on the timing belt/chain cover. Without these marks, a timing light simply can’t be used.
This is important because a number of high-end timing lights say they work with electronic, computer-controlled, and distributorless ignition systems (DIS), but that’s a little misleading. It’s not that there’s anything wrong with the instrument itself — they can give you all the readings you need — but rather that there’s no way for you to adjust the timing without the kind of computer setup that’s usually only found in dealerships and professional auto shops. You can see if something is wrong but can’t do anything about it.
What timing lights do
A timing light — in effect, a strobe light — is used in conjunction with the marks mentioned above. A cable attaches to your number one spark plug and detects the electrical pulse when the plug fires, sending an electronic signal to your timing light and causing it to flash.
If the timing is right, the timing marks on the motor appear stationary at zero. This is because the frequency of firing (and hence the flash of the timing light) matches when the piston is in the optimum position, creating ideal combustion.
If it’s slow (retarded) or fast (advanced) you’ll see stationary marks either a few degrees before or after zero. The timing light doesn’t make the adjustment; it shows you whether the timing is correct or off. Mostly, zero is the right place to be, but race engineers might either advance or retard ignition to affect performance across different parts of the rev range.
Top dead center (TDC) is when the number one piston is at its highest position in the cylinder (farthest from the crankshaft). It’s often the starting point for setting the timing.
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Features
Types of timing lights
There are two main types of timing lights and two main designs.
Inductive: This timing light is used to check the timing at idle, which is the standard approach and fine for most vehicles.
Advanced: This model offers adjustment to allow timing to be checked at different engine outputs. Mechanics working on performance or race engines often want this extra flexibility.
The design is either a pencil or pistol grip.
Pencil grip: This type is more portable and easier to get into confined spaces, but it can be tricky to hold and usually has only basic features. However, it’s usually battery powered, so you don’t have to worry about compatibility with 6-volt or 12-volt systems.
Pistol grip: These models have become more common, and many provide additional details like battery and alternator voltage, dwell (the length of time the charge is held within the distributor coil), and tachometer (for engine revolutions per minute).
Questions to answer
When it comes to choosing the right model, the questions you need to answer depend on the engine or engines you’ll be working on but could include the following:
- Will it work on any number of cylinders?
- Will it work on two- and four-stroke (cycle) engines?
- Will it work on 6-volt and 12-volt electrical systems?
- Are the cables long enough to access the timing marks comfortably? (Not all timing lights have cables.)
- What is the maximum revolutions per minute the timing light can display?
- Does it have an on/off switch? (Many don’t. You need to keep your finger on a button or trigger for it to operate.)
- Does it come with a spark plug tester? (Sometimes a misfire isn’t the result of poor timing but simply a worn-out plug.)
- Is the device durable? (Timing lights get dropped. ABS is a popular material — it’s the same stuff used in many helmets. Others have rubber armor.)
- Is there a hand guard? (It gets pretty hot around an engine. Some pistol-grip models offer protection for the front of your hand where it wraps around the handle.)
- Does it have a backlit LCD screen? (This makes it easy to read in poor light.)
- Does it come with a case?
Safety
Setting your timing doesn’t require any special protective equipment, but there is inherent danger when working on an engine, especially if you’re distracted. For that reason, make sure you’re 100% alert. If your child wants to help (which is always nice) make sure they’re old enough to be fully aware of what’s going on. Tell them where it’s safe to help and where it isn’t. If they aren’t at that age yet, keep them out of the garage until you’re done.
Did You Know?
Your timing light needs to be connected to the number one spark plug wire. If you don’t know which one that is, you need to find a workshop manual that has the details. You can’t just guess!
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Timing light prices
Inexpensive: You can find cheap timing lights for around $30. They’re quite basic induction models, although a few include a spark plug tester. The main criticism of units at this price is unreliability.
Mid-range: There’s a wide choice of both induction and advanced timing lights between $40 and $100. Tools in this range will cover the needs of most home mechanics.
Expensive: Top-quality timing lights can be $150 and more. In terms of functionality, they probably don’t offer anything more than the mid-range models; however, they normally have very rugged construction, a high degree of accuracy, and a powerful bulb that can be seen in normal daylight — an area where cheaper timing lights can prove disappointing.
If you need to check the timing of a high-performance engine like a two-stroke motorcycle, check the maximum revolutions per minute the timing light is capable of reading. Some don’t read above 5,000, which may not be high enough.
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Tips
The following works for most distributor-based ignition systems but bearing in mind the kind of problems that can occur if your timing is off, we strongly suggest contacting a professional if you’re not comfortable doing this. There are also a number of videos online, so it’s worth a quick look. You may find details for use on your specific vehicle or one that’s very similar.
- Make sure the engine is off. Lift the hood.
- Attach the red wire from your timing light to the positive (+) terminal of the battery.
- Attach the black wire from your timing light to the negative (-) terminal of the battery.
- Connect the pickup clamp (or trigger clip) to the first spark plug wire. That’s the first in the firing sequence, not necessarily the one closest to you. It doesn’t really matter where you connect it; it senses the pulse through the insulation.
Your timing light is attached and ready to go. You can now move on to checking and adjustment, which can differ from one vehicle to the next. Once again, the internet is a great source of info for good general guidance.
FAQ
Q. Can I set a vehicle’s timing without a timing light?
A. It is possible with some older engines, though by no means all. You’ll probably need a vacuum gauge, and the procedure is both more involved and less accurate than using a light unless you’re an experienced auto technician. Given the relatively low cost of a timing light, it’s an investment worth making if you’re going to do this job on a regular basis.
Q. Can timing lights be used on motorcycle or marine engines?
A. In theory, as long as you can see the timing marks and get the light onto them properly, a timing light can be used on any gasoline engine. Actual procedures might differ, so you’ll want to check that. Unsurprisingly, there is a vast amount of information online, though you may need patience to find the right details.
Q. Do timing lights need batteries or a mains connection?
A. They don’t use mains. Some use internal batteries (usually the pen type), and others use the vehicle’s battery. The latter are easily identified by red and black wires ending in crocodile clips. As long as your vehicle’s battery is working okay, it will supply all the power you need. Check the tips above for how to attach your timing light properly.
