Best Spark Plug Gap Tool – 7 Options Reviewed

I’ve spent countless hours wrenching in the garage, and I can tell you firsthand that setting the spark plug gap correctly is critical for smooth engine performance and fuel efficiency. Trying to adjust modern spark plugs with an old-school flat disc gauge can easily damage the delicate electrode, potentially causing misfires. That’s why having the best spark plug gap tool is non-negotiable for anyone doing their own maintenance. We’ve put seven top-rated options through their paces—from traditional feeler gauges to modern precision gapping devices—to help you find the right fit for your toolbox and ensure your proper gap setting every time.

IMAGE	PRODUCT NAME	AMAZON LINK
	CTA Tools 3235 Spark Plug Gapper	View on Amazon
	Toolwiz Spark Plug Gap Tool with 32 Blade Steel Feeler…	View on Amazon
	Lounsweer Air Spark Plug Cleaner Spark Plug Gap Tool Kit…	View on Amazon
	Spark Plug Gap Tool with 32 Blade Steel Feeler Gauge,…	View on Amazon
	PQY Universal Spark Plug Gap Tool with 32 Blades Steel…	View on Amazon
	A & E Hand Tools 4450A E-Z Grip Spark Plug…	View on Amazon
	CTA Tools 3238 9 Wire Spark Plug Gap Gauge	View on Amazon

CTA Tools 3235 Spark Plug Gapper

If you’re looking for a simple, heavy-duty tool that focuses purely on gap adjustment without the fuss of extra features, the CTA 3235 is a fantastic choice. This gapper is built to withstand the rigors of a professional garage, offering a straightforward mechanical advantage when you need to safely compress the electrode without bending or snapping it off. It’s an ideal complement to a dedicated feeler gauge set, providing the necessary leverage for precise, controlled adjustments.

Key features that stand out:
– Professional Grade Construction: Built with heavy-duty materials for long shop life.
– Resilient and Flexible Design: Simple design minimizes complexity and points of failure.
– Specialized Automotive Tool: Designed specifically for safe electrode adjustment.

Pros:
– Excellent build quality for frequent use.
– Provides high leverage for adjusting tighter gaps safely.
– Simple, no-frills mechanism is reliable.

Cons:
– It requires a separate measurement tool (like a feeler gauge) to check the gap.

Best for: Mechanics who already own a comprehensive set of feeler gauges and need a robust tool just for setting the gap.

Expert Opinion: This CTA tool is the workhorse of gappers. It doesn’t measure, it adjusts. For tough, standard plugs, this sturdy design gives you the confidence to make the adjustment without damaging the center electrode.

Toolwiz Spark Plug Gap Tool with 32 Blade Steel Feeler Gauge, Gapping Tool for Most 10mm 12mm 14mm 16mm Thread Spark Plugs, Red

The Toolwiz setup provides an excellent all-in-one solution, pairing a precision screw-style gap setter with a high-quality 32-blade feeler gauge. This combination makes it incredibly easy and quick to achieve an accurate gap setting. Crucially, this tool works by safely reducing the gap by turning a knob, placing controlled pressure on the ground electrode. The inclusion of the durable feeler gauge made from 65 manganese steel ensures you have reliable measurements right out of the box.

Key features that stand out:
– Complete Set: Comes with both the gapper and a dual-marked (inch/mm) feeler gauge.
– Wide Compatibility: Works with common plug sizes (10mm, 12mm, 14mm, 16mm).
– Easy & Quick Adjustment: Simple knob mechanism saves time and effort compared to manual bending.
– Accuracy Tip Included: Suggests using a slightly smaller gauge to account for spring-back.

Pros:
– Comprehensive kit at a great price point.
– Protects the electrode during adjustment.
– Feeler gauge is high quality and accurate.

Cons:
– Cannot enlarge the gap, only reduces it, requiring careful initial setting.

Best for: DIYers and enthusiasts working on a variety of vehicles who need a safe and precise all-in-one solution.

Expert Opinion: We appreciated the thoughtful inclusion of the “spring-back” adjustment tip. This shows the manufacturer understands the nuances of gapping and helps users achieve a truly accurate measurement the first time.

Lounsweer Air Spark Plug Cleaner Spark Plug Gap Tool Kit Sandblaster Cleaner Tool with Blasting Abrasive Material and Fabric Clean Bag for Remove Carbon Buildup Motorcycles, Lawn Mowers, Vehicle

This is less a simple gap tool and more a comprehensive spark plug maintenance kit. The Lounsweer package is designed for those who want to revitalize fouled plugs rather than just replace them. It uses compressed air and abrasive media to strip away carbon buildup, restoring plugs to a near “like-new” state. After cleaning, the included precision spark plug gapping tool allows you to correctly set the spacing for optimal ignition timing.

Key features that stand out:
– Complete Spark Plug Maintenance Kit: Includes sandblaster, gapper, abrasive material, and cleaning bag.
– Powerful Carbon Removal System: Uses 7.7 CFM air power to effectively clean tough carbon deposits.
– Durable Professional Construction: Features anti-rust brass fittings and an aluminum base for stability.

Pros:
– Extends the life of expensive spark plugs, saving money over time.
– Highly effective at restoring engine performance from fouled plugs.
– Features intuitive controls and easy vertical mounting.

Cons:
– Requires an external air compressor to operate the cleaning function.

Best for: Small engine mechanics, high-performance tuning shops, or serious DIYers who frequently deal with fouled plugs (e.g., in dirt bikes, lawn mowers, or classic cars).

Expert Opinion: While overkill for someone who only checks gaps once a year, the carbon removal feature is invaluable. For engine builders who test and reuse plugs, having this level of cleaning power combined with a gap setter makes this a genuinely professional-grade solution.

Spark Plug Gap Tool with 32 Blade Steel Feeler Gauge, Spark Plug Gapping Tool for Most 10mm 12mm 14mm 16mm Thread Spark Plugs, Red

Very similar in design and functionality to the Toolwiz, this gapper also provides a universal fit for common plug sizes and includes a reliable 32-blade feeler gauge. What makes this specific kit stand out are the detailed instructions and the focus on reducing electrode wear. The manufacturer provides adjustment tips recommending that users rotate the knob slightly backward before measuring the final gap to prevent the electrode from rebounding and ensuring accuracy. The inclusion of gloves is a nice touch for clean handling.

Key features that stand out:
– Adjustment Tips: Focuses on mitigating rebound for higher accuracy.
– Universal Fit: Compatible with most non-preset 10mm, 12mm, 14mm, and 16mm plugs.
– High Quality Feeler Gauge: Made of flexible 65 manganese steel for reliable, long-term use.
– Kit Includes Gloves: A small added value for handling plugs cleanly.

Pros:
– Excellent instructions for precision gapping.
– Safe method for gap reduction, protecting electrodes.
– Good value with the included feeler gauge.

Cons:
– Limited compatibility; does not fit 18mm or certain long/short reach plugs.

Best for: Beginners and DIY mechanics who value clear, detailed instructions on how to achieve the most accurate spark plug gap settings possible.

Expert Opinion: The emphasis on the specific procedure—rotate back slightly, then measure—is a crucial piece of knowledge often overlooked. This tool ensures even new users don’t accidentally wear down the electrode coating or get a false reading.

PQY Universal Spark Plug Gap Tool with 32 Blades Steel Feeler Gauge for Most 10mm 12mm 14mm 16mm Spark Plugs Red

The PQY gapping tool is built with a sleek aluminum body and a matte texture, giving it a premium feel while providing the same precise, controlled gapping action as other screw-type models. It features a key difference in its included feeler gauge: it has a special 0.010-inch brass blade. Brass is softer than steel and is recommended for use with electronic ignitions where excessive contact with the feeler gauge could potentially damage sensitive components.

Key features that stand out:
– Aluminum Construction: Durable, lightweight body with a matte texture finish.
– Brass Blade Included: Features a brass blade in the feeler gauge set, ideal for specific electronic ignition systems.
– Spring-Back Tip: Offers guidance for compensating for electrode spring-back during adjustment.

Pros:
– High-quality aluminum build.
– Brass blade inclusion is excellent for sensitive applications.
– Quick and easy adjustment method.

Cons:
– The included feeler gauge range is slightly smaller (up to 0.88mm) than others.

Best for: Users working on modern vehicles with electronic ignition systems where the delicate brass blade offers extra protection during measurement.

Expert Opinion: The use of aluminum and the specific inclusion of the brass blade make this stand out. It targets the user who is concerned not just about the mechanical gap, but also the protection of the plug’s electrical components.

A & E Hand Tools 4450A E-Z Grip Spark Plug Gap Gauge, Orange

Sometimes, simplicity wins. The A & E E-Z Grip is the modern evolution of the classic coin-style gap tool. It’s incredibly fast to use, highly portable (thanks to the pocket clip), and features an ergonomic “E-Z Grip” design that makes checking the gap much more comfortable than traditional flat discs. While it doesn’t offer the precision needed to adjust delicate iridium plugs, it’s the fastest way to check the gap on standard copper plugs and small engine plugs. It includes a specific recess for making slight adjustments to the electrode.

Key features that stand out:
– E-Z Grip Design: Comfortable, easy-to-hold plastic body in high-visibility orange.
– Pocket Clip: Highly portable for use around the shop or field.
– Dual Scale: Metric gapping scale included on the reverse side.
– Electrode Adjuster Recess: Built-in section for slight bending adjustments.

Pros:
– Inexpensive and highly portable.
– Fastest method for checking gaps.
– Comfortable and easy to read.

Cons:
– Not suitable for precision adjustments on expensive, delicate spark plugs.

Best for: Quick, routine maintenance checks on lawn equipment, standard vehicle copper plugs, and users who prioritize speed and portability.

Expert Opinion: We recommend keeping one of these in your toolbox and one in your glove box. It’s perfect for rapidly ensuring a plug is near spec, especially on older engines. Just remember to be gentle when using the adjustment recess, as bending can be less precise than using a screw-type setter.

CTA Tools 3238 9 Wire Spark Plug Gap Gauge

When absolute precision is required, many professionals turn to wire gauges, and the CTA Tools 3238 is a heavy-duty, reliable option. Unlike disc or flat feeler gauges that can sometimes give a false reading due to the bevel of the electrode, the circular wire provides a highly accurate measurement of the actual gap space. This specific gauge offers 9 essential sizes ranging from 0.025 to 0.060 inches, covering the vast majority of automotive applications. Its heavy-duty construction ensures it won’t bend or warp under normal use.

Key features that stand out:
– Wire Gauge Accuracy: Provides a more accurate measurement than flat gauges.
– Wide Range of Sizes: Covers 9 common gap sizes from 0.025″ to 0.060″.
– Heavy-Duty Construction: Built for strength and durability in a shop environment.

Pros:
– Extremely accurate measurement readings.
– Covers most modern engine specifications.
– Very durable and reliable design.

Cons:
– Does not include metric measurements (though conversion is easy).

Best for: Professionals and high-performance builders who need the absolute most accurate gap measurement possible, especially for modern ignition systems that are highly sensitive to small variations.

Expert Opinion: If you’re using high-end plugs or forced-induction applications, the accuracy offered by a wire gauge like the CTA 3238 is unmatched. Use this to measure, and a separate, dedicated gapper (like the CTA 3235) to adjust.

Helpful Comparison Short Insights

When choosing the best spark plug gap tool, it really comes down to what you are gapping and how often you do it.

For general use, the screw-type gapping tools (like Toolwiz, PQY, and Spark Plug Gap Tool Red) offer the safest and most controlled way to close the gap on modern plugs without damaging the electrodes. They are highly recommended if you are installing pre-gapped plugs that need slight fine-tuning.

If you are dealing with sensitive, expensive Iridium or Platinum plugs, avoid using the traditional coin or wire gauges for adjustment. While wire gauges (CTA Tools 3238) are superior for measurement accuracy, attempting to bend the delicate electrode with them can cause irreparable damage. Use the wire gauge to check, and a controlled setter tool (like the Toolwiz or PQY) to gently adjust.

If your spark plugs are heavily fouled, the Lounsweer Kit is the only solution here that actively cleans and restores the plugs, adding significant value beyond simple gapping.

The A & E Hand Tools E-Z Grip is the fastest and simplest for quick inspections, making it the top choice for small engine repairs and general checks where extreme precision isn’t paramount.

Final Verdict

Choosing the right spark plug gapping tool depends entirely on your needs, but we found clear winners across different categories:

Best Overall Precision & Value: The Toolwiz Spark Plug Gap Tool with 32 Blade Steel Feeler Gauge takes the top spot. It offers a safe, controlled method for adjustment, bundles an excellent feeler gauge, and includes all the necessary features for the majority of DIY and professional spark plug work.

Best for Professional Accuracy: The CTA Tools 3238 9 Wire Spark Plug Gap Gauge is the gold standard for measurement. If your engine requires absolute precision and you rely on wire readings, this heavy-duty gauge is the most reliable option.

Best Full Maintenance Solution: The Lounsweer Air Spark Plug Cleaner is in a league of its own. If you need the ability to clean and restore plugs before gapping them, this comprehensive kit is an essential investment.

Comprehensive FAQ: Choosing the Best Spark Plug Gap Tool

Why is the correct spark plug gap so important for engine performance?

The spark plug gap determines the length of the jump the electrical current must make. If the gap is too narrow, the spark will be weak, leading to incomplete combustion and poor fuel economy. If the gap is too wide, the ignition coil may not be able to bridge the gap, causing misfires, hesitation, and potentially rough idling. Proper gapping ensures maximum burn efficiency and smooth engine operation.

What are the main types of spark plug gap tools available?

There are three primary types. Wire gauges (like the CTA 3238) are highly accurate for measuring the true gap. Disc or Coin gauges (like the A & E E-Z Grip) are fast, inexpensive, and great for quick checks on standard plugs. Screw-type Gappers (like Toolwiz or PQY) are dedicated tools that provide controlled leverage to safely reduce the gap on delicate electrodes without bending or snapping them.

Can I use a regular feeler gauge set to gap my spark plugs?

Yes, a regular set of steel feeler gauges can be used to accurately measure the gap. However, using them (or the coin tool) to manually adjust the gap by bending the ground electrode can be risky, especially on expensive plugs. For safest adjustment, especially on platinum or iridium plugs, always use a dedicated screw-type gapping tool.

Are screw-type spark plug gap tools compatible with all spark plugs?

Most modern screw-type tools (like the ones reviewed here) are compatible with standard 10mm, 12mm, 14mm, and 16mm spark plugs. However, they are not typically compatible with 18mm plugs or unusual long-reach/short-reach plugs. Always check the tool’s specifications against your plug size before purchase. They are best suited for non-preset plugs that require adjustment.

Should I gap Iridium or Platinum spark plugs?

Generally, no. Most iridium and platinum plugs come pre-gapped from the factory. The delicate materials and fine-wire electrodes are very sensitive, and adjusting them risks damaging the tip or the coating. If they absolutely must be adjusted, use a controlled gap setter (like Toolwiz) very gently, avoiding traditional bending methods.

How often should I check or set my spark plug gap?

You should always check the gap on new spark plugs right before installation, as transit and handling can cause slight changes. For maintenance, the gap should be checked whenever you change your plugs, usually corresponding to the service interval recommended by your vehicle manufacturer (typically every 30,000 to 100,000 miles, depending on the plug type).