Toolwiz Spark Plug Gap Tool with 32-Blade Steel Feeler Gauge — Red, 10–16mm Fit, Hardened 65M Steel

Keep ignition consistent by setting spark plug gaps accurately before installation or while servicing engines. This compact red Toolwiz gapper combines a mechanical gap-adjusting tool with a dual-marked, hardened 32-blade feeler gauge so you can quickly match or fine-tune gap specifications without bulky equipment. It’s crafted for home mechanics, tuners, and pros who need a portable, repeatable way to compress electrodes to the correct clearance.

Which spark plugs will this Toolwiz gap tool work with?

The Toolwiz gapper fits most standard 10mm, 12mm, 14mm, and 16mm threaded spark plugs. It is not suitable for 18mm threads, long-reach or short-reach plugs, or plugs with preset gap designs where the electrode cannot be safely adjusted.

• Compatible: standard 10mm–16mm thread spark plugs
• Not compatible: 18mm threaded plugs, long/short reach types
• Iridium/Platinum: usually factory-gapped; do not require routine adjustment

How do I use the gapper to get an accurate spark gap?

Place the spark plug in the tool’s cradle, select the feeler blade that approximates your target gap, and slowly turn the knob to compress the electrode until the gauge slides or fits as specified. Because electrodes may spring back slightly, starting with a feeler blade slightly under the target size gives a more reliable final gap.

• Install plug in the tool before adjusting
• Turn knob gently to compress electrode to gauge thickness
• For precision: use a blade 0.001"–0.002" smaller than the target gap

What limitations and precautions should I know?

This Toolwiz device only reduces or closes the gap; it cannot widen a gap. Do not attempt to adjust plugs with delicate, fixed electrodes or those the manufacturer specifies not to tamper with. Use light, controlled force to avoid damaging the electrode or insulator.

• Only decreases gap—cannot enlarge it
• Avoid forcing on iridium or pre-set electrodes
• Apply steady, gentle turns to prevent chipping

What does the included feeler gauge offer?

The package includes a 32-blade feeler gauge stamped with both imperial (0.001"–0.040") and metric (0.03–1.0 mm) measurements. Blades are made of hardened 65 manganese steel, polished for durability and consistent thickness so you can verify gaps quickly across a wide range of values.

• 32 blades for fine increments and broad coverage
• Dual-marked imperial and metric readings for versatility
• Hardened, polished steel for repeatable accuracy

Who is this for: The Toolwiz Spark Plug Gap Tool suits DIY mechanics, motorcycle and small-engine enthusiasts, tuners, and technicians who need a portable, accurate way to reduce spark plug gaps for standard thread sizes. If you regularly service vehicles with 10mm–16mm plugs and want a lightweight, shop-ready tool with a precise feeler kit, this set streamlines gap adjustment without needing heavy shop machinery.