The spark plug, that small, seemingly unimportant looking piece of automotive hardware is often taken for granted. While it is quite true that the humble spark plug is small, it is, however, a crucial part of the car’s engine. Without the spark plug, the vehicle would not even work at all and become practically useless. Spark plugs are critical components ensuring that a car’s ignition system runs smoothly.

Upon installation of this crucial device, painstaking attention should be given to spark plug calibration. The distance represented by a bent metal pin or the electrode at the center at the very tip of the spark plugs is known as the gap. This minuscule distance varies depending on the type of engine, but it would be somewhere between 0.028″ and .060″. Modern spark plugs are usually pre-gapped according to the vehicle it goes into, therefore it is always advisable to ascertain the distance with spark plug gap tool or gapping tool before installation.

Top Pick

OEMTOOLS 26 Blade Master Feeler Gauge

For this reason, every respectable car owner should have the best spark plug gap tool in his toolbox. There are hundreds, if not thousands of these tools in the market today and once again we do the hard work of sifting through the gimmicks and just giving you those worthy of your hard-earned money. We gathered 7 of the best spark plug gap tools, starting with our top pick, the OEMTOOLS 26 Blade Master Feeler Gauge. This spark plug gap measuring tool stood out among the rest with its intuitive 26-blade design made out of tempered steel blades. Its laser-etched blades give you the information in inches and millimeters, with a convenient thumb notch for easy blade extraction, truly great value for money!

TOP 7 Best Spark Plug Gap Tools:

While it may appear straightforward, the sheer number of spark plug gap tools available in the market today presents the problem of too many choices. This is not a bad thing but having a substantial amount of options can make choosing one a bit daunting to say the least. You do not have to face that problem though, because we did! We did the legwork and came up with 7 of the most bang-for-the buck spark plug gap tools. Take a look at these down below.

OEMTOOLS 26 – Blade Master Feeler Gauge

Featuring 26 heavy-duty hardened tempered steel retractable blades, this feeler gauge is built to last for a long time. The blades themselves are clearly marked out with laser-etched SAE and Metric measurements. This means that whatever unit of measurement or scale you are used to you are covered. The rust and corrosion-resistant blades are snugly secured in a chrome-plated main shaft with a handy thumb notch for easy blade retrieval. The 26 blades have a range of 0.04mm up to 1mm with increments of 0.05mm, covering a wide range of vehicles. In addition, this feeler gauge also has a variety of other measurement uses, such as valve clearances and shim measurements.

OEMTOOLS 25025 26 Blade Master Feeler Gauge: image

Check Price

A & E E-Z Grip Spark Plug Gap Guide

A new form factor with a handle makes this E-Z grip quite easy to use. The versatile tool can also be used as an adjustment device for the electrode. Spark plug gap tools are already simple from the start but the E-Z Grip took it to another level by including a punch hole that can be used to adjust electrodes simultaneously. The ergonomic handle and the recess at the tip truly make this amazingly affordable tool. Familiar graded edge style has a wide range of measurements starting from .02 inches up to 0.8 inches. While larger than other spark plug gap tools, it has a clip that makes it a breeze to carry as you go about your tinkering.

A & E Hand Tools 4450A E-Z Grip Spark Plug Gap Gauge: image

Check Price

Spurtar 32-Blade Feeler Gauge

If you are looking for precision, look no further than the Spurtar 32-Blade feeler gauge. This tool gives you 32 accurate measurements. You would be glad to know that it does so in imperial and metric measurements. The blades start with a thickness of 0.03mm to 1mm, with the numbers being laser etched into the metal itself. With this many blades of varying thicknesses, you can be assured of its wide compatibility. The great thing is that it may contain 32 blades but it still weighs less than 5 Oz making it ultra-portable. Besides, the steel blades are tapered to facilitate ease of use. Specially constructed from # 65 manganese steel, it has excellent anti-rust properties.

Spurtar 32 Blades Steel Feeler : image

Check Price

OEMTOOLS Ramp Style Spark Plug Gap Tool

A ramp style spark plug gauge is probably the oldest design as well as the most popular. It has the classic round shape that has its edges tapering off from the thinnest to the thickest when they meet. A hole at the top can be used as an electrode adjustment tool should the need arise. This spark plug gap tool is small enough to fit in your key chain, and it has no loops that can snag in your pocket. Using it is straightforward, with its edges starting from 0.50mm to 2.5mm it is applicable for a variety of engine spark plugs. Inch measurements are stamped on one side and metric on the corresponding side ensures no confusion on whatever unit of measurement you are familiar with.

OEMTOOLS 25352 Ramp Style Spark Plug Gap Gauge: image

Check Price

CTA Tools The Gapper Ramp Style Spark Plug Gauge

Nicknamed ‘The Gapper’, this spark plug gap tool from CTA Tools is built to withstand just about any abuse you throw at it. It heavy-duty metal construction is a die-cast piece that lends it extra durability and toughness. Built to both measure and adjust electrode gaps, this gapper is stamped with imperial system of measurement. The units of measurements are clearly etched on to the metal surface and are quite easy to read. The hole near the top of the unit can be used to adjust the electrodes gap. It’s measurement range starts from 0.02 inches up to 0.1 inches that gradually builds up with 0.01 increments.

CTA Tools 3235 Ramp-Type Spark Plug Gapper: image

Check Price

Performance Tool’s Coin-Type Spark Plug Gapping Tool

This coin-type gap tool from Performance Tools may just be the smallest spark plug gapper yet. It may be small but it packs a punch starting with having both SAE and Metric units of measurements. Its gradually tapering edge starts of with .020 to .100 (SAE) and from 0.5 to 2.5mm (Metric) and this esures full usability with whatever unit of measurement you are familiar with. This is almost required to be put on a keychain as it can easily be misplaced because of its small size.

Performance Tool W80535 Spark Plug Gap Gauge: image

Check Price

CTA Tools Wire-Type Spark Plug Gauge

This handy little spark plug gauge form CTA Tools come in a wire type configuration in a rugged and durable all-steel construction. Along with the 9 gap measurement loops, it also has a gap adjustment tool that is already built-in. It’s 9 measurement ranges start from 0.025 up to 0.060 inches that go up by increments of 0.05. This gives the tool a relatively narrow range of gap measurements. This tool however is specifically intended for newer iridium-type spark plugs and can handle delicate adjustments. The units are etched on the metal surface and is very clear to see.

CTA Tools 3238 9 Wire Spark Plug Gap Gauge: image

Check Price

A comprehensive buyers guide

While we did go out of our way in doing the legwork, we still want you, our readers, to be as knowledgeable as possible. Before dishing out our selection we want to give you a brief overview as to what makes a great and dependable spark plug gauge tool. We will also cover how to gap spark plugs with feeler gauge as well as every basic thing you need to know about spark plugs.

The types of spark plugs

To understand how to use a spark plug gap tool we have to brush lightly on what kinds of spark plugs are available for our engines out there. Before starting the selection process for spark plug gap checker, we need to be able to know for certain what spark plug your vehicle has. Currently, there are four major types of spark plugs that are commonly used in modern cars today.

Copper-nickel spark plugs – These spark plugs are the grandfather of all spark plugs, and have been around for a long time. They have a solid copper core with a nickel-alloy electrode, Yes, copper-nickel spark plugs are old but some high-performance engines require them because of copper’s conductivity properties. Older engines particularly on classics also use them so they continue to be in production to this day.

Silver spark plugs – While not as old as copper-nickel plugs, silver spark plugs also can be found on older vehicles and benefit from the superior conducting properties of silver. They are also more durable than the copper-nickel variant of spark plugs. Just be extra careful when using a spark plug gapper as the tips can be a bit brittle.

Platinum spark plugs – Platinum spark plugs just swapped out nickel for platinum, retaining the same copper core. These spark plugs are also made to cope with newer engines, particularly ones that can withstand higher energy systems. Platinum is more durable than nickel, therefore it is not unusual for these spark plugs to last from 80k to 100k miles before ever needing to be replaced.

Iridium spark plugs – These spark plugs were introduced as coil-on-plug systems became more popular in the market. Iridium became an option for Platinum and Nickel spark plugs, offering even more durability. Besides, the smaller diameter design increased the efficiency by a huge margin.

The types of spark plug gap tools

When you replace your spark plugs, there is a huge chance that they are already gapped according to specifications. However, you will never be sure unless a gap tool is used before installation. Below are the three kinds of spark plug gauge tools that are in use today. Please note that most modern spark plug gap tools used for measuring also double as spark plug gap adjustment tool themselves.

Feeler Gauge

This type of spark plug gap tool is reminiscent of a swiss army type of mechanism with calibrated metal strips instead of tools in the fold. The metal strips have varying thicknesses that correspond to the spark plug gap distance, whatever the requirement of the engine may be. This spark plug gauge comes with a varying number of blades, and usually comes with millimeter and inch markings. This makes it easier to read no matter what metric you are familiar with. This can be a bit bulky, depending on the number of blades included in a set.

Wire loop style gauge

If the multiple blades of a feeler gauge appear too bulky for you, then a wire spark plug gap tool may fit your requirement. They look like a coin and not much bigger but with wire loops of varying thicknesses around it. These wires are calibrated according to varying gap measurements corresponding to different spark plug requirements. This iridium spark plug gap tool will usually feature a non conductive but strong electrode adjustment attachment that can be used to widen or lessen the electrode gap. However because of its circular nature, it can only accommodate a limited number of measurements.

Ramp style gauge

The ramp style gauge is another circular adaptation of a spark plug gapping tool but instead of loops the edge instead tapers from the thinnest outer edge and gets thicker incrementally as you get to the middle part. This style also has the added convenience of also acting as the spark plug gap pliers by itself. The ramp allows it to adjust the electrode incrementally. By far this is the most convenient and cheapest gauge among the three types but can suffer from inaccuracy as the ramps can be bent and misaligned.

Qualities of a top-notch spark plug gap tool

Construction – For a spark plug gap tool autozone to be considered as good quality, the way it is made should be spot on. Needless to say, the construction should be heavy-duty, preferably stainless steel. This will prevent corrosion and rust, ensuring accurate measurements all the time. It is a good idea only to buy from reputable stores and those brands that are known for their quality to have the best value for your money.

Markings – The best spark plug gap guide tools would have laser-etched markings engraved on to the surface of the tool. Low-quality ones will only have a printed design and this will not be able to hold up to wear and tear pretty well. It is hard to imagine low quality marking being able to survive inside a toolbox for a long period. Get only those with marks that are etched into the tool itself and not just printed on.

Calibration – Ensure that the tool that you want to use will have at least two metric indicators, such as millimeters and inches to avoid inconsistencies. Furthermore, this will allow you to use whatever metric system you are comfortable with to begin with. This feature will also avoid any unnecessary conversions which save a substantial amount of time.

Ease of use – some gap measuring tools have unnecessary add-ons that are just gimmicky and may hinder its function. It is better to choose one that is not complicated to operate. In this regard, wire type gauges may be the winner.

Flexibility – When considering flexibility and with a wider range of applications, nothing may beat the feeler gauge as they can come with a varying number of blades that correspond to gap measurements. Some may even come with over 35 blades, which you can simply pull out as needed and tucked in when not in use.

Frequently Asked Questions (FAQs):

How do I gap spark plugs without a gapping tool?

The short answer is no as it would be completely pointless to adjust the gap without accurately measuring the distance. Without a spark plug gap tool, one would be going in blind, and may end up worsening the engine’s performance instead of improving it.

You can also wach video How to Gap a Spark Plug:

What happens if I don’t gap my spark plugs?

Simply putting in a replacement spark plug without checking their gaps entails the risk of your engine misfiring and the timing being off. Furthermore, your ignition system itself can become compromised and not work at all.

How do I know if the gap needs readjusting?

Now this is why you need a spark plug gap tool, as it is the only way you can hope to accurately measure a spark plug’s gap. It varies per vehicle but when you measure your spark plugs and it is not the one for your engine, then you know that it needs adjustment.

Can the wrong spark plug cause a misfire?

If the gap is way off the recommended measurement, then it would contribute to misfire when the engine operates. Gaps widen in the lifetime of a spark plug so it is advisable to check on the gaps within regular intervals.

Wrapping up

Sure, you can adjust the gap of a spark plug even without a spark plug gap tool. However, the gap that we are talking about here needs to be on point and precise. An incorrect distance can lead to your engines misfiring and cause damage in the long run. Your vehicle’s ignition system depends on the precise placement of its parts to run flawlessly. A good quality spark plug gap tool will ensure that your engine runs according to specification in its lifetime. This makes the spark plug gap tool a necessary addition to any vehicle owner’s toolbox.