To ensure your spark plugs work, you must make sure the gap between the side electrodes and the center is properly calibrated. The right gap ensures arcing occurs at the right voltage to ignite your fuel. It generates the necessary combustion to make the engine run. The best tool for spark plug gap measurement will allow you to perfectly adjust the gap.
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Why Use a Spark Plug Gap Tool?
Whether you want to maximize your vehicle’s performance or ensure the setting is correct, using the best spark plug tool is important. A spark plug gap tool lets you obtain the exact measurement recommended by the manufacturer, which boosts the spark plug’s efficiency.
This is done by making sure it generates a spark that is able to ignite the fuel and air mixture necessary to power the vehicle. Consult the owner’s manual for correct spark plug gaps for your make and model.
Enables the Adjustment of Pre-Gapped Plugs
Many spark plugs will indicate they are pre-gapped. However, they may work in different engines and may not be correct for your vehicle. The spark plug gap will need to be adjusted to ensure the vehicle performs as intended.
Pre-gapped plugs have a specific heat range, ignition gap, and torque that works for the engine. A new one may not have the same gap size. If a larger or smaller one is installed, there may be a decline in the engine’s performance.
Ensure that you have the correct gap measurement, then double-check that your gap is set correctly to the car’s recommended setting while installing.
Allows You to Achieve Performance Goals
Whether you want to race or desire more control over your spark plug settings, checking the gap allows you to achieve better performance.
The spark plug’s gap size determines how well it fires. A gapping tool helps you open the gap to the precise factory measurement found in the owner’s manual. This will boost the spark plug’s efficiency by allowing it to put out a spark large enough to ignite the fuel and air mixture in the engine.
Prevents Premature Failure
Having the correct spark plug gap reduces burned electrodes. This can lead to premature failure of your spark plugs. Should the gap not be correct, the electrodes may burn, causing a failure.
Types of Tools
- Feeler Gauge: A feeler gauge has several metal wires or blades of various thicknesses. It looks like a pocket knife. Each wire or blade has a thickness measured in thousandths of an inch/millimeters. With a wide variety available, you will be able to measure almost any gap.
These are ideal for iridium spark plugs or other spark plugs containing precious metals. The feeler gauges tend to be more accurate than other types. The downside is that you need pliers to bend your spark plug electrode. The blades will become deformed if you use them to adjust your plug.
- Wire Loop Gauge: This type of gauge is shaped like a coin. However, it has wire loops with various thicknesses coming out from its edge. It has the same accuracy as the feeler gauge and has a hook that bends to spark plug electrodes.
The only drawback is the limited number of loops, making it ineffective for odd gap sizes.
- Coin Style Gauge: The coin-style gauge is named for its coin-like shape. It has a thin outer edge with measurements around it. As you move around the gauge, it becomes thicker. It is also known as a ramp style gauge.
It allows you to bend your spark plug electrode. However, accuracy may become an issue because of the gradual slope of the edge. It is perfect for traditional copper spark plugs but should not be used with iridium ones because it will damage the precious metals in this type of plug.
Things to Consider
There are three things to consider when searching for the best spark plug gap tools. These tools will help you do a proper job and make the process much easier. You will also end up with a good quality tool that will last.
Markings
The best tools have markings that are laser-etched on the steel. Not only are they easier to read, but they don’t rub off as easily. They will also not fade over time. It is easier to obtain precise measurements from them since the size is indented into steel. It can be matched precisely to the gap without the aid of a marker to indicate points.
Calibration
Find a gauge calibrated to your measuring system. For example, if you are comfortable with imperial measurement, use one with this calibration. You can find those marked with both metric and imperial if you want to skip the mental math needed for the conversion.
Find one that contains a range like your spark plug’s gap size for the best accuracy.
Material
Look for tools made with heavy-duty steel material. They will be great for measuring platinum and iridium. Steel is the best material since it resists corrosion and is durable. Look for one from a reputable brand to ensure your tool won’t rust, bend, or corrode at its edges.
Ease of Use
Select a simple tool. All you need to know how to do is set the tool on the gap/electrode to reduce/increase the gap. Wire gauges tend to be easier to use. You only have to rotate them while measuring.
Flexibility
The instrument needs to be flexible so that the user can easily change sizes. Feeler gauges are the most flexible since they contain various-sized blades that you can push back, interchange, or pull out with ease.
The Best Spark Plug Gap Tools
These are just a sample of available spark plug gap tools. Choose one that is well suited for your make/model and comfort level. Make sure that the design is durable, and, most importantly, that the measurements stay intact. If it meets all the above requirements, then you will have it in your toolbox for years to come.
Best Overall: OEM Tools Blade Master
This spark plug gap tool contains 26 calibrated blades measuring from 0.015” to 0.025”. You can obtain the exact gap value in metric or imperial. The hardened steel blade has laser-etched measurements on the center of each tempered steel blade. Blades are durable and resist corrosion/rust.
Pros:
- The blades contain a thumb notch that makes removing each piece easy
- Easy to clean chrome-plated finish
- Blades have a smooth edge and weigh only 3.2 oz.
Cons:
- May rust in humidity
- Need continual lubrication to prevent rusting
Best Runner Up: A & E Hand Tools E-Z Grip Gauge
The A & E Hand Tool is a universal spark plug gauge. The hard plastic handle makes it easy to grip and comes in black and orange. Size ranges from 0.20”-0.08” with metric conversions located on the opposite side. The scale will accommodate older vehicles plus ones with a distributorless ignition system.
Pros:
- Has a pocket clip for easy access
- Makes gapping plugs easier
- Extremely accurate and contains an adjustment hole for widening
- Provides a large amount of leverage, making small adjustments easy
Cons:
- Chrome coating may flake
- Tiny imperfections on the metal edge
Best Budget: CTA Tools Spark Plug Gapper
This heavy-duty tool is extremely durable and strong. It uses die-cast metal and is incredibly accurate. You can use it for readjusting and measuring a spark plug gap, and it uses the imperial measurement system with laser-etched markings on the side.
Pros:
- Size ranges from 0.02”-0.1” with increments of 0.01”
- Easy to read with a 7/16” diameter hole for keyring/spark gap opener
- Helps to accurately resize plugs with the included electrode tool
Cons:
- May not be entirely accurate with smaller values
- Steel might rust and markings can fade
Best Long-term Durability: CTA Tools 32389 Wire Spark Plug Gap Gauge
This tool contains a rugged steel construction with a built-in gap adjuster, and heavy-duty steel construction means it has superior strength, durability, and corrosion resistance. It is very flexible as well.
Pros:
- 9 wire gauge ranges in sizes from 0.025” to 0.060” for the best approximation
- Covers common gaps
- Able to adjust platinum and iridium plugs
Cons:
- May bend too easily
Best For Performance: K-Motor Performance Spark Plug Gap Tool
If performance is your ultimate goal, this is the perfect tool for you. This tool will properly gap your spark plugs and allow them to burn at top efficiency.
There is some discussion surrounding the proper spark plug gap. Some experts indicate that if you drive normally, with a mixture of street and highway driving and obeying speed limits, the spark plug can be increased by 0.010” for improvements in fuel economy.
They also recommend that if you are heavy on the gas or enjoy high speeds that the spark plug gaps be reduced by 0.010”.
Pros:
- Great if you want to try various gaps but do not want to hit the electrode on cement to close it
- Works with 14 mm plugs
- Provides precision gap setting
Cons:
- Leaves behind indentations
- Incompatible with FA20 spark plugs
The best spark plug gap tools offer precision and accuracy over inferior models. Their measurements will not fade and the tool will not corrode. When selecting a plug, make sure the markings are easy to read. You will also want a durable tool that won’t bend or rust over time.
Be sure to take the best care of your tools, and they will last a lifetime.
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