There are models in different formats (for example, with single blades or in the form of a roll) and also the radius calibrators used to measure concave or convex rays. Did you know you can easily gap spark plugs using a feeler gauge? Follow these steps: Step 1: Examine Gap Meets Specifications The CTA Tools Spark Plug Gap gauge is made up of a strong and durable all-steel construction built to resist corrosion. It’s a circular gauge with easy-to-read, laser-etched sizes on its body in sizes ranging from 0.025 to 0.060 inches with 0.005 increments. Nine wire rings on the gauge's outer edges help you to accurately measure, increase, and decrease the gap size. Mechanical assemblies such as machines are built up from a series of mating parts. The fit of those parts is often designed to be within a specified tolerance that assures reliable operation for the machine – for example, the fit of a piston into the cylinder of an engine. If there is too tight a fit or clearance between the piston and cylinder, the engine may suffer from excessive wear and friction, shortening the life of the unit and resulting in maintenance costs and downtime. If the gap or clearance is too wide, combustion gases may escape during compression, reducing the engine performance. To make certain that gaps and clearances are within specified limits, engineers, mechanics, and machine operators rely on the use of measuring devices such as a feeler gauge. This article covers what feeler gauges are, the various types that exist, the gauge sizes, and provides some examples of typical uses for these instruments.

Achieve better spark plug performance. The size of the gap of a spark plug determines its firing performance. The gapping tool will help you manually open the gap to the exact factory measurement recommended in your owner's manual. That way, you boost the efficiency of the spark plug in putting out a large enough spark to ignite the air and fuel mixture in your engine. A wire-type feeler gauge is a little different to the standard shim arrangement. Instead of featuring a series of graded metal leaves or blades, the wire feeler gauge instead has a series of rigid metal wires. Below, we have listed some of the most common types, materials and models of feeler gauges. Most are available either as full sets or as individual blades. Wire Type Feeler Gauges To alter the spark gap, twist a little, the ground electrodes away or toward the center electrodes. Step 3: Now Use Any Other Tool if RequiredThe OEM Tools Blade Master has 26 calibrated blades that can measure sizes ranging from 0.0015 to 0.025 inches. You can get the exact value of the gap in either SAE or metric system (inches and millimeters). The measurements are laser etched in the middle of each blade. The blades are made of hardened tempered steel, which is long-lasting and resistant to rust and corrosion.

The number of blades or leaves – Different feeler gauge sets will feature different numbers of blades. On the low side, 10 or less, with 13, 15, 25, 26, 31 being more common blade counts, all the way up to over 100. To learn more about the other varieties of gauges, see our related guide covering the types of gauges. What is a Feeler Gauge? The most common type of feeler gauge, called a straight leaf or straight blade gauge, consists of straight blades of uniform width constructed of high carbon steel sold in a set to cover specific dimensional values. However, there are variations on this standard that serve specific purposes. Are you confused about how this instrument works? See the step by step below, where we use as an example the measurement of a spark plug:Correctly gap your new spark plug. Your original spark plug may come pre-gapped by the manufacturer. These plugs have a designated ignition gap, heat range, and torque that works for your engine. A new spark plug may not have the same gap size, and if you install it with a smaller or larger gap, you may notice a significant decline in your engine’s performance. As well as, when repairing or replacing spark plugs, a technical service center measures or establishes the distance between two electrodes by using a feeler gauge. Some of the most common sizes you will likely find yourself using include 1mm, 1.5mm and 2mm feeler gauges. However, the ones you tend to use the most will of course depend largely on what type of work you are doing.

This measurement will give us the number of threads per inch on UNC, UNF, NPT, BSPP, and BSPT threads, and the distance in millimeters between two consecutive ridges on metric threads. The best feeler gauge for a given application will depend mainly on the size of the gaps you are measuring, how durable you need the gauge to be, and what sorts of materials or parts you are measuring gaps between. Measurements that involve the use of a feeler gauge are generally very small and are always very accurate. Auto repair technicians need accurate gap measurements when working with spark plugs, distributors, or valves.

\n\t\t\tHalfords Spark Plug Gauge Metric

Now that you know that there are different models of gap gauge, you need to evaluate which is the most suitable for the equipment you want to measure.

However, for many standard engineering and mechanical applications, tempered or stainless steel is often the preferred material. Brass can also be a good option if you need something durable, but somewhat softer and less likely to scratch than steel. If the thread is cylindrical, we measure any thread from crest to crest. Whether the thread is tapered, we measure the fourth or fifth thread from crest to crest. 04. Measure the Pitch of the Thread But it is not the only function they perform: they also take care of alleviating the heat which is generated in the combustion chamber to the cooling system. The CTA Tools Spark Plug Gapper has a heavy-duty construction built for strength and durability. It’s made up of a die-casted metal to harden the steel and increase the accuracy of the unit. It can be used for measuring and readjusting the spark plug gap. The gauge is calibrated in the imperial system, and the size markings are laser etched on the rugged steel construction. This CTA gap adjustment tool only weighs 1.44 ounces and will offer over 30 accurate gaping measurements before you need to readjust it. It also includes one electrode-adjusting tool. The unit is designed to adjust the plug without pressuring the center electrode. The tool can be used at home and in a professional garage.

Uses and Applications of Feeler Gauges

You can buy shorter or longer versions, with short ones tending to measure about 75mm in length. Long feeler gauges are less common but still quite widely used for specialised applications, particularly in engine maintenance and repair. These models can be anywhere between 8 inches and 2 feet in length. Metric and Imperial Feeler Gauges Prevent burnt electrodes. Used spark plugs may have a slight discoloration at the electrode (negative probe). Further inspection may reveal that the gap between the ground electrode and the center electrode is wider. If the gap is not properly aligned, the electrode will continue to discolor and will eventually burn away.