5 Best Feeler Gauge Sets – 2019 Review

Last updated on October 16th, 2019 at 03:44 pm

Sometimes the gap between objects or parts can be bigger or smaller than required and it can be catastrophic. This applies especially to systems or subsystems that need precision measurement between them or their parts. A perfect example is a car engine. It has several parts that seem flush or in contact with each other while in reality, some have small gaps between them. If these gaps are ignored during an engine rebuild exercise, they can cause poor engine performance. For example, an incorrect engine valve clearance can cause the engine to run rough. This is why you need a precision tool such as a feeler gauge for valve clearance. Feeler gages are also useful for measuring the flatness of engine surfaces such as the cylinder head and setting up a guitar’s Action among other uses.

What is a Feeler Gauge?

A feeler gauge is a precision-measurement tool used to measure the thickness of very narrow gaps and the flatness of surfaces. It consists of either a stack of metal sheets or wire strips of known thickness or gauge. There are different types of feeler gauges. The most common types are the steel feeler gauges, brass feeler gauges, and wire feeler gauge.

Types of Feeler Gauges

  1. Steel Feeler Gauge Set

    As the name goes, steel feeler gauges are made of steel. However, for increased strength and flexibility, they are mostly made out of tempered carbon steel or stainless steel. Others are alloys of manganese. Comparatively, the stainless steel feeler gauges are superior to other varieties of steel gauges because they do not rust. The others, if not properly oiled rust very quickly.

  2. Brass Feeler Gauge Set

    This thickness gauge tool has brass leaflets. The non-ferrous property of brass makes the gauge suitable for applications where there is a magnetic field. Unlike steel gauges, the brass leaflets do not stick to magnets thus allowing you to work effectively in magnetic fields.

  3. Round Wire Feeler Gauge

    A wire type feeler gauge is fondly known as a gapping tool. It is made of wire loops of calibrated sizes. Although it can be used like other feeler gages, this tool is mostly used to gap spark plugs. Its small size and a limited number of gauge sizes make it unsuitable for other applications of thickness feelers.

5 Best Feeler Gauge Gap Measuring Tools

Proto J000TL 25 Blade Long Feeler Gauge SetStarrett 66B Thickness Gage Set With Straight LeavesPrecision Feeler GaugesABN Universal Standard SAE and Metric Offset Valve Feeler GaugeHotop Stainless Steel Feeler Gauge Dual Marked Metric and Imperial Gap Measuring To
Users' Ratings
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  • Consists of 25 steel blades
  • Blades are 12 inches long
  • Each blade is etched with both empirical size and metric equivalent
  • Steel holder has a locking thumbscrew
  • Gages are made from high carbon steel
  • Has 31 thickness feelers
  • The feelers are made of tempered steel
  • Includes a blade lock knob
  • Comprises of 32 leaves
  • Gauges are made from manganese steel
  • Gauges are foldable
  • Each Blade is Laser engraved with inches and millimeters
  • Feeler gauge set is 89mm long
  • Includes a single brass feeler gage
  • Includes 16 angled feeler gauges
  • Gauges are constructed from hardened tempered steel
  • The thickness gauges are laser etched with inches and equivalent millimeter sizes.
  • Blades are bound within a blade protector that has a lock knob to hold them in place.
  • Consists of 32 leaves
  • Made from 65 manganese steel
  • Has a non-slip lock nut to hold blades in place
  1. Feeler gauges are long enough to access deep places
  2. When the tip wears down, you can cut the end off and be left with reasonable length
  3. Amercian made
  1. Has a ton of blades to suit many applications
  2. Leaves are well-tempered and don't bend
  3. It is an American piece!
  1. Gauges are highly foldable
  2. Manganese steel feelers are resistant to abrasion
  1. Angled blades are good for accessing tight spaces
  1. The multiple blades increase tool's versatility
  2. Super cheap
  1. Does not ship with a case
  1. Quite expensive
  1. This thickness gauge tool rusts very quickly if it is not properly oiled.
  1. Feeler gauges may rust if not oiled properly
  1. Susceptible to rust if not oiled
Number of Leaves/blades 25 blades 31 leaflets 32 Leaves 16 blades 32 blades
Design Straight set Straight set Straight set Angled set Straight set
Measurement system Empirical/metric Empirical/metric Empirical/metric Empirical/metric Empirical/metric
Range .0015" - 0.040" 0.0015" - 0.035" 0.0015" - 0.035" 0.05" - 0.019" 0.0015" - 0.035"
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Combination Feeler Gauges Detailed Reviews

25 Blade J000TL Proto Feeler Gauge Long

Proto feeler gauge set has 25 blades bound within a steel blade holder. Each blade is 12 inches long and 1/2 inches wide with thickness size laser etched on one side in both empirical and metric units.

How to use a feeler gauge to measure a gap

Time needed: 2 minutes.

The following is an easy step-by-step procedure for using a feeler gauge tool to measure narrow gaps.

  1. Identify the gap or surface that needs to be measured

    The first step in measuring clearances is to identify the exact place or object that need to be measured. It could be a valve clearance, piston ring end, spark plug gap, or the surface of a cylinder head.

  2. Check the specification sheet or repair manual

    After identifying the place that needs measurement, check the specification sheet or manual for the correct measurement. For example, unless otherwise indicated, the gap between the ground electrode and center electrode of a spark plug should never exceed 0.055 inches.

  3. Choose the appropriate set of feeler gauges

    Knowing the right size of a gap helps to choose the right set of feeler gauges. The best feeler gauge is one that at least has the desired measurement. For instance, if you are measuring a very tight gap (say in the range of a thousandth of an inch), such as the flatness of a transmission steel plate, you need a set that at least has a gauge for that measurement. For larger gaps, you can always stack together a couple of blades.

  4. Slide the wire gauge or blade into the gap

    To measure the clearance between two objects, slide the wire gauge or the calibrated blade into the gap. If the wire or blade slides freely, select the next measurement up and if it is snug, choose the next gauge down. You should feel a drag or a slight grab when you move the proper gauge back and forth through the slot.

  5. Read the feeler gauge

    Feeler gauges are easy to read. Each blade or wire gauge is labelled with its respective metric or imperial size measurement or both. Therefore, if you are using a single gauge, you only need to read the measurement on it. Otherwise, if you have stacked together two or more blades, you need to add together the different sizes.

  6. Keep the feeler gauge safe!

    Because the gauges are delicate, they need to be stored carefully. For the steel feeler gauges, you need to apply lube on them first before storing safely into the toolbox. This helps to prevent rusting and also allows you to swivel the blades out smoothly. Also, ensure that the thumbscrew is snugged properly to hold the blades together. For a round wire type feeler gauge, hang it securely on a tool wall after oiling.


An electrical engineer by profession who used to work at a solar microgrid firm as an O&M supervisor. There, he realized that having the right tools for the trade is equal to getting the job half done. That's what inspired him to start this website!

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