How To Gap Iridium Spark Plugs - 5 Easy Steps To Fix it! (2024)

Little do you know, aside from other vehicle familiar concerns, how to gap iridium spark plugs is one of those you should no way fail to bear in mind.

“Doesn’t it seem like a bit too tricky to get the hang of?” Many might think so, as it sounds like a specialized spectrum. Worry no more with our in-depth guide to walk you through every minor detail!

What Is A Spark Plug?

A spark plug, so-called a sparking plug, is an internal combustion engine component that has two electrodes isolated by an air gap.

Through the small spark generated between these two electrodes from the high-pressure ignition system, the spark plug ignites the air-fuel mixture as fuel is atomized and air reaches the engine’s cylinders.

To do so, the electrodes and the insulator between them must be capable of tolerating high temperatures.

Yet, the insulator also has the quality of handling electric stress up to thousands of volts well.

The gap of a spark plug’s mission in this operation is to maintain the length that benefits the spark energy.

Meanwhile, the insulator’s shape leaves a certain impact on the conducting temperature.

If it is too cold, there’s a possibility the operation will result in carburization and gap shorting; if it is overheated, then an initial phenomenon is more likely to occur.

We can encounter a spark plug in several distinctive materials, with Nickel, Copper, Iridium, and Platinum being the most prevalent.

Many producers also utilize a little piece of ceramic as an insulator on this engine part.

Regardless of types, this part is vital in any automobile, as a faulty spark plug can lead to severe problems like thumping noise when driving.

How To Gap Iridium Spark Plugs - 5 Easy Steps To Fix it! (1)

What Are NGK Iridium Spark Plugs?

Thanks to its advanced technology, NGK Iridium spark plugs are among the best-performing types of spark plugs globally.

Speaking of features, these components function as a thermo-edge design for the central electrode and employ highly valuable Iridium metal at the tip of the center electrode, which has a diameter of 0.6mm.

Unlike any ordinary spark plugs, its exquisite Iridium patterns allow you to run your vehicles at the smoothest and longest operation through miles. There is a chance you can get the most straightforward starting and greater combustion.

Even better, exceptional acceleration over expanded mileage and lower electrode wear rate is no longer far-reaching in such a case.

What about the benefit of the special thermo edge design for center electrodes? If excellent antifouling conductivity is what you are looking for, then we would say seeking no further than NGK Iridium spark plugs!

How To Gap Iridium Spark Plugs - 5 Easy Steps To Fix it! (2)

Do You Need To Gap Iridium Spark Plugs?

Is it necessary to gap NGK Iridium spark plugs? The answer is a big old yes!

The better spacing the spark plugs are, the more optimization your engine can perform at. That is why it matters that much for you to get the knack of the NGK spark plug gap size chart and follow it thoroughly.

One way or another, you can view it as a consequential chain of action.

Here comes the details: This characteristic has an impact on the engine’s fuel and air combustion.

And that, in turn, will have an impact on the car’s performance. The gap thus needs to be wider for more sparks to form, leading to an increase in the engine’s efficiency.

This broadening may be in effect in some instances, such as with customized engines. When gapping spark plugs, you must pay close attention to adjustments and measurements.

Otherwise, you risk yourself making unrepairable mistakes.

Importance Of The Spark Plug Gap

As we’ve mentioned above, the spark plug gap plays a vastly vital role in running your car’s movement perfectly.

That said, there is not much choice for you to choose from. You must ensure the plugs have an appropriate gap, or your engine performance is on the decline.

This clearance in the midst of the side and center electrodes is in demand of being positioned right so that arcing at the proper voltage ignites the fuel and provides the combustion that runs the engine.

How To Gap Iridium Spark Plugs - 5 Easy Steps To Fix it! (3)

How To Gap NGK Laser Iridium Spark Plugs

Step 1:

The first step on how to gap Iridium spark plugs is to find a feeler gauge or a gap gauge.

Step 2:

Remove the spark plug and clean it. This step will not matter much in how to properly gap iridium spark plugs if yours is brand new.

Yet, in case you’re testing a spark plug that is already in the car for an extended time, the contact points may get dusty and need purification.

Take note for your daily reminder: Don’t ever tidy a spark plug with abrasive materials!

Step 3:

The next step is to measure the existing gap in the spark plug. To determine the exact number, you need to run your feeler gauge or gap gauge through the electrodes.

Once you have a measurement, record it and compare it to the recommended setting listed in the manual to see if it’s the right direction to go or not.

Step 4:

It’s now time to make whatever needed adjustments.

To Increase The Gap Size

Bend the ground strap up to the required height with a spark plug gapping tool or needle-nose pliers.

Beware to never allow the gapping tool or pliers to contact with porcelain or the Iridium center electrode.

To Decrease The Gap Size

Follow the same procedure as before. Nevertheless, instead of bending the ground strap up, bend it down to the appropriate height.


  • Remember to be extremely cautious when making any modification. Saying so, you should in no way bend the electrode more than a few thousandths of an inch. Though the engine part is tough, it’s not built to withstand a lot of tension.
  • Besides, avoid hitting the central electrode. If the center electrode gets damaged by excessive prying or the bottom electrode might have accidentally snapped off, it may then be time for you to get the new one.

Call to mind that when it comes to prying precious platinum core electrodes or metal iridium, they may be highly sensitive.

That’s why it’s critical to utilize the right spark plug gapping tool for doing the task.

Step 5:

Using a calibrated gapping tool to re-check the gap. Repeat the procedure of adjusting the tool until it fits snugly between the electrodes.

Also, don’t ever conduct the testing process with a round gapping tool. Otherwise, a permanently damaged spark plug is on the way.

How To Check Gap Laser Iridium Spark Plugs

How to check NGK spark plug iridium gap may not be as daunting as you might think once you know the ultimate simple way to get it done right.

Step 1: Get The Equipment

All you have to do is merely pick up a fitting measurement on your feeler gauge or gas gauge.

Step 2: Measuring

In the case you can no way locate the correct tool within the gap, it is in the circ*mstance of widening.

What if the tool doesn’t even touch the electrodes while being through the gap? Then, it must be too large and demand a narrowing.

Another situation is that the tool and the gap fit perfectly together. Then, congratulations for no more adjustments needed!

In most circ*mstances, gapping your Iridium Power plugs is not at all essential. The ultra-efficient firing power architecture will adjust itself for slight deviations in the factory set gap, even if they are little.

If you opt to re-gap your Iridium spark plug, do so with caution since incorrect gaping can harm or even destroy the porcelain center or Iridium center electrode.

How To Gap Iridium Spark Plugs - 5 Easy Steps To Fix it! (4)

Consequences Of Improper Spark Plug Gap

What happens if you don’t gap your Iridium spark plugin the way it should be? The consequences may then strike terror in your mind.

In that case, engine issues are inevitable. There is a high likelihood your vehicles will suffer the symptoms as follows, including misfires, increased plug wear, spark plug fouling, loss of power, or even poor gas mileage.

That way, neither too small nor too wide a gap benefits your motor running. If the gap is so tiny, it can give rise to the weakness of a spark.

Due to this, it’s impossible for the combustion process to finish successfully.

What about too broad? Then, it might cause the spark plug to not ignite properly, resulting in misfires at uplifted speeds.

Torque Recommendation

Plug SizeIridium heads
10mm flat seat10 to 157 to 11
12mm flat seat15 to 2511 to 18
14mm flat seat35 to 4026 to 30
14mm taper seat9 to 207 to 15
18mm flat seat43 to 5232 to 38
18mm taper seat20 to 2715 to 20

(1 N.m = 0.1020 kgf.m)

In case you’ve been tracking down for some useful suggestions, then you’ve landed in the right place!

The figure above shows the recommended torque to install the spark plug accordingly.

However, please note that you should apply these installation torque values in the table to fresh spark plugs with no previous threads lubrication only.

Otherwise, you should lower the numbers by about one-third to prevent unnecessary overtightening.

In A Nutshell

That’s how you grasp how to gap iridium spark plugs. No longer troublesome, these little tricky details are for you to idealize your automobile conquest!

Hopefully, our article can be of great use to you. Let’s roll up your sleeves and do your DIY project. See you then!

As an enthusiast and expert in automotive maintenance, particularly in spark plug technology and gapping procedures, I've accumulated extensive knowledge and hands-on experience in ensuring optimal engine performance. I have a deep understanding of the intricacies involved in maintaining spark plugs, specifically highlighting the significance of properly gapping iridium spark plugs.

In the article you provided, the following concepts are discussed:

  1. Spark Plug Basics:

    • Definition: A spark plug is a crucial component in an internal combustion engine with two electrodes separated by an air gap.
    • Function: It ignites the air-fuel mixture in the engine's cylinders through a spark generated by the high-pressure ignition system.
    • Materials: Spark plugs can be made of Nickel, Copper, Iridium, Platinum, and may include a ceramic insulator.
  2. NGK Iridium Spark Plugs:

    • NGK Iridium spark plugs are highlighted for their advanced technology, featuring a thermo-edge design and utilizing valuable Iridium metal for optimal performance.
    • Benefits: Improved starting, combustion, acceleration, and lower electrode wear rate are emphasized.
  3. Importance of Spark Plug Gap:

    • The spark plug gap is crucial for engine fuel and air combustion, directly affecting the car's performance.
    • Proper gap size is essential for efficient engine operation.
  4. How to Gap NGK Iridium Spark Plugs:

    • Steps for gapping iridium spark plugs are outlined, including the use of a feeler gauge or gap gauge.
    • Importance of cleaning the spark plug and measuring the existing gap is stressed.
    • Adjustments are made to either increase or decrease the gap size as needed.
  5. Consequences of Improper Spark Plug Gap:

    • Engine issues such as misfires, increased plug wear, fouling, loss of power, and poor gas mileage can occur if the spark plug gap is not set correctly.
  6. Torque Recommendations:

    • Recommended torque values for installing spark plugs are provided based on plug size and type.
    • Caution is advised to apply these torque values to fresh spark plugs without previous thread lubrication.
  7. In A Nutshell:

    • The article concludes by summarizing the importance of understanding how to gap iridium spark plugs for an ideal DIY automotive maintenance project.

By covering these topics comprehensively, the article aims to equip readers with the knowledge and confidence needed to effectively gap iridium spark plugs for optimal engine performance.

How To Gap Iridium Spark Plugs - 5 Easy Steps To Fix it! (2024)


What special procedures applies to setting the gap on iridium spark plugs? ›

Always use a special spark plug gapping tool to change the gap. Do not change the gap on platinum, iridium or twin tip spark plugs, as the fine electrodes may get damaged.

What tool is used to gap iridium spark plugs? ›

Feeler Gauge

Ideal for use with iridium spark plugs and other plugs containing precious metals, feeler gauges are more accurate than other types. A drawback is the fact that you'll need a pair of pliers to bend the spark plug electrode since the blades will become deformed if you try using them to adjust the plug.

Do iridium plugs need gapping? ›

NGK do not recommend gap adjustment for precious metal spark plugs. A variety of techniques are used to adjust electrode gaps. An appropriate method and tool should be used for gap adjustment although it has come to our attention that a variety of improper methods are used that lead to implications.

How tight should iridium spark plugs be? ›

Tighten the spark plug finger-tight until the gasket reaches the cylinder head, then tighten about ½ – ⅔ turn more with a spark plug wrench. (Taper seat: About 1/16 turn more.)

How do I know if my spark plug gap is wrong? ›

Engine knocking, or engine pinging, is a classic sign of an engine that has incorrectly gapped spark plugs. Engine knocking is the result of incomplete or delayed engine combustion, especially under acceleration.

Can you side gap Iridium spark plugs? ›

The Iridium center is fragile. Once you fracture it, even the slightest bit, that plug is done. This is what NGK says; "The re-gapping of fine wire spark plugs that have very small diameter platinum or iridium alloy electrodes is not recommended due to the risk of damaging the electrodes.

What is the best spark plug gap for performance? ›

For most racing applications, you usually want the plug gap to be between 0.020 and 0.040 of an inch. Most engine builders seem to settle around 0.035 of an inch. Factors such as the type of ignition you run, cylinder heads, fuel and even timing can affect how much gap will work best for you.

How tight to tighten spark plugs? ›

Screw in the plug until it “seats,” that is, it's finger tight. Turn the plug an additional ¼ turn. If you're installing a new plug, screw in the plug until it seats, then turn it an additional 2/3-3/4 turn. This crushes the washer between the plug and the head, forming a tight seal.

What is the best spark plug for older engines? ›

Copper spark plugs run cooler and provide more power in performance driving situations. They are often installed as original equipment in turbocharged engines and engines with higher compression ratios. Copper spark plugs are also often used in older (pre-1980s) vehicles with a distributor-based ignition system.

What do you use to bend the spark plug gap? ›

Most measuring tools will also feature a flat edge typically used for bending the bottom electrode on the spark plug to adjust the gap slightly. A coin-style gap measure is usually the cheapest option, and works by running the edge of the "coin" through the gap until you reach a point where it stops.

Which is better iridium or platinum spark plugs? ›

Iridium is a far stronger metal than platinum, capable of taking up to eight times as much wear and tear as a platinum spark plug before losing efficiency. This means that iridium spark plugs are less likely to fail than platinum spark plugs, need replacing less often, and perform better under tough conditions.

What tool is used to fix spark plugs? ›

A plug socket, ratchet, extension if needed, a plug gauge, plug boot pliers, a short piece of rubber fuel hose to start the plugs without cross threading. A universal socket may be needed, or a wobble extension, if there isn't a straight shot to the plugs. A special ratchet wrench to remove and replace spark plugs.

Can you side gap iridium spark plugs? ›

The Iridium center is fragile. Once you fracture it, even the slightest bit, that plug is done. This is what NGK says; "The re-gapping of fine wire spark plugs that have very small diameter platinum or iridium alloy electrodes is not recommended due to the risk of damaging the electrodes.

Are Champion iridium spark plugs pre gapped? ›

Today, Champion®spark plugs come pre gapped, eliminating the need for this step most times. You should double check that the gap is correctly set; check your owner's manual to find the distance for the spark plug gap and use a gap gauge or feeler gauge to check the distance.

What is the difference between regular spark plugs and iridium? ›

Iridium is said to be six times harder and eight times stronger than platinum with a 700° higher melting point. Iridium spark plugs have extremely fine electrodes while retaining excellent wear characteristics. Thanks to its strength, iridium spark plugs can last up to 25% longer than comparable platinum spark plugs.


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