You can buy feeler gauges from your local hardware store. Feeler gauges are often referred to as “blades” or “leaves. ” You can also remove the feeler gauge from the rest of the set if you need to reach it into a hard-to-reach spot.
Don’t try to force a feeler gauge into a gap that’s too small since you could damage the parts or bend the gauge. Your feeler gauge will either have a consistent thickness or a tapered end that gets thinner. If you have a tapered feeler gauge, the thinnest section is the actual measurement. If the feeler gauge gets stuck in the gap, spray a lubricant like WD-40 onto it so it can slide out easily.
Usually, thousandths of an inch are listed with 3 numbers after a decimal point and hundredths of a millimeter have 2 numbers after a decimal point. Some feeler gauges will have both measurements printed on them. At least one of the measurements will be labeled so you know which one’s which.
Oil helps the feeler gauges move freely so they don’t get caught in gaps. If you don’t oil the feeler gauges when you’re finished using them, be sure to oil them before the next time you use them so they don’t get stuck in the gap you’re measuring.
Many spark plug gaps need to be between 0. 028–0. 060 inches (0. 71–1. 52 mm). If your spark plugs don’t have a correctly-sized gap, it can lead to engine misfire, low gas mileage, or even loss of power.
Don’t measure the gap on a piston ring while it’s outside of the cylinder since it won’t be accurate. If the gap in the ring is too small, use a file to grind the ends down until it has the gap size you need. A piston ring has a gap that’s too large will reduce the efficiency of your engine.
To get the best tone and make it easier to play on an electric or acoustic guitar, the top string should have a height of 0. 030 inches (0. 76 mm) and the bottom string should be 0. 015 inches (0. 38 mm).
