How to Close the Spark Plug Gap | An In-Depth Detailed Guide

How to Close the Spark Plug Gap

The spark plug gap is a critical factor in spark plug firing. It often affects engine running quality and can lead to incomplete combustion of air and fuel. The spark plug is the ignition device used in internal combustion engines. It supplies the electrical discharge to ignite the air-fuel mixture in the combustion chamber and thus to start the engine. Let’s learn how to close the spark plug gap.

Various factors affect the spark plug gap, including engine speed and load, temperature, air-fuel mixture, etc. In this article, I will introduce the factors affecting the spark plug gap and different ways to close the spark plug gap.

How to Close the Spark Plug Gap 

How to Close the Spark Plug Gap

Spark plug gaps are one of the most overlooked parts of maintaining a vehicle. Most people focus on the oil levels, brake pads, and tire air pressure. Ignoring the spark plug gap can lead to your car not starting, or worse yet, damage to your engine. The first step to adjusting the spark plug gap is to get a spark plug gap tool, which you can detect at your local auto parts store.

Next, you can get rid of the spark plugs from the engine, place them one at a time in the gap tool, and tighten the Allen of the device to close the gap. Once the hole is closed to the appropriate size, run the engine, check and clean the plugs and gap them again until perfect. 

Close Spark Plug Gap with Feeler Gauge

When tuning your bike or car engine, you must ensure that everything is in working order and top shape. One of the simple things to check is the spark plug gap. Be sure to check it intermittently to ensure that the spark plug is working to the best of its ability.

It can do with a feeler gauge to measure the gap between the electrodes. And the metal cylinder on the top of the spark plug. For optimal results, use a 0.030-inch gauge. The electrode gap should be between 0.022 and 0.039 inches to ensure that your engine runs at its optimum performance!

Close Spark Plug Gap with Dial Gauge

It would help find the proper spark plug gap to get maximum results. It would help if you used a dial gauge, which you can use to measure the gap between the spark plug.

You will have to measure this with each new pin and make adjustments. Find the proper gap first and remove the gap. Take the gauge and stick it into the hole.  

Turn the plug to write down the numbers. If the number is below what you want, you need to tighten the gap. If the number is above what you want, loosen it and put it back together. Now you have the proper spark plug gap!

How to Close the Spark Plug Gap with Sand Paper?

How to Close the Spark Plug Gap

Sanding a spark plug is one of those tasks that seems pretty easy in theory but can be tricky to implement. Here’s a brief consultant on how to do it, along with some handy tips. First, you’ll want to get a few things together. You’ll need sandpaper that ranges from 120 to 220 grit, which can purchase at most major stores. Along with the sandpaper, you’ll need some safety glasses and gloves. 

Once you’ve got everything, go ahead and start sanding your spark plug until the gap is the proper size. Be sure to change the paper often and check your progress regularly to ensure that everything is going smoothly. Once you get the gap to the proper size, you’re ready to get your engine running and enjoy your newly tuned vehicle! 

How to Close the Spark Plug Gap with a Hair Dryer? 

How to Close the Spark Plug Gap with a Hair Dryer? 

Many mechanics use heat and a towel to close the spark plug gap. Put the plugin in the flame of the hairdryer for about 15 to 20 seconds, just enough to get the plug hot. Then quickly wipe the pin with a clean, dry cloth. The expansion process should close the gap and improve the plug’s firing.

In this case, the heat from the towel may be a drawback, and perhaps a better method is to use a wet finger or even a damp paper towel. You may find that it will save you a lot of time and effort.

How to Close the Spark Plug Gap with Pliers?

How to Close the Spark Plug Gap with Pliers?

Spark plug gap is commonly set by counting the number of threads on the head of the plug and subtracting the number of lines on the engine block. Holes are then checked with a feeler gauge to see if they are within manufacturer specifications. To close a spark plug gap, first insert the feeler gauge blade into the space between both electrodes, and then remove it vertically.

Tips to Close Spark Plug Gap 

Here are some levels you can take to achieve the proper spark plug gap.

  • Always consult your vehicle’s manufacturer for the proper spark plug gap.
  • Use a feeler gauge to evaluate the gap very carefully.
  • Use a feeler gauge to measure the gap.
  • A feeler gauge is a device that uses to measure small gaps between parts.
  • Only use feeler gauges that make for use in cars.
  • Use the feeler gauge in a straight line across the spark plug.
  • You should use the feeler gauge to measure the gap from the center of the electrode to the center of the electrode.
  • Make sure that there are no chips on the electrodes.
  • Always check your owner’s manual before you try to adjust the gap.

Frequently Asked Questions

What Is The Optimal Spark Plug Gap For My Car?

  • 0.035 inch (BMW)
  • 0.030 inches (Hyundai/Kia)

How Do You Adjust The Spark Plug Gap? 

  • I use a feeler gauge. 
  • I use a dial gauge.

How Do I Measure The Spark Plug Gap?

Measure the spark plug gap with Gapping Tool

What Happens If You Don’t Gap Your Spark Plugs Correctly?

  • You get some bad gas mileage
  • You can burn out your spark plugs
  • Engine won’t start (or will start and immediately stop)

What Happens If The Point Spark Plug Gap Is Too Large?

  • The car gives the dreaded “Spark Erro” message on the dashboard
  • You’ll have a trial for starting the car


Spark plug gap is typically set at the factory when the plugs process. However, the spark plug gap will change over time due to erosion and buildup. There are many different reasons for changing the spark plug gap, and it’s essential to follow the engine manufacturer’s recommendations. 

In addition, the spark plug gap can vary depending on the type of spark plug you have, the season of the year, and even geographic location. Keep reading to learn more about spark plug gaps and what you can do to make sure your spark plugs fire the way they are supposed to.