Ultimate Guide For Spark Plug Gap

Although buying a spark plug for your engine is necessary, gapping the spark plug to your engine gap size is more important. So, do you just ask yourself “How do I gap a spark plug?” Here is a pictorial simple guide to walk you through the process.

What Is The Spark Plug Gap?

The word “spark plug gap” refers to the distance between the spark plug tip and the center electrode, and it is essential in the functioning of the spark plug. Typically, spark plug gaps for car engines are 0.06 to 1.8mm (0.024 to 0.071 in). Additionally, the gap which is the separation between the side and center electrodes, is adjusted so that an arc at the appropriate voltage ignites the fuel and produces the combustion that powers your engine.

Importance Of Spark Plug Gap

• The spark plug gap gives a more powerful spark which is necessary for the air/fuel mixture in your combustion engine
• Better assurance of good fuel ignition
• Gives a longer electric arc
• Improve engine performance and horsepower
• Prevent misfire, thus leading to engine-long lifespan
• Spark plug gapping reduces emissions

Consequences Of Incorrect Spark Plug Gap

Although you may see a spark plug gap as something unnecessary, it is important you know that it plays a unique role in your spark plug. In addition, when you incorrectly gap your spark plugs it can damage your engine by causing engine misfires, poor fuel economy, plug fouling, rough-running engine, the engine will require more voltage to ignite, and premature plug wear. For these reasons, you must always gap your spark plugs to the manufacturer’s gap size specification.

Step-By-Step Guide On How To Gap A Spark Plug

For your engine to operate properly, you need to gap your spark plug directly. The spark plug’s firing temperature is influenced by the gap size and is directly related to the engine’s fuel and air combustion. Because spark plug gapping can be learned by measuring and making the necessary adjustments, below is a simple guide to walk you through.

PART A- Measure The Gap

(1) Vehicle’s Gap Specification

If you just bought a new spark plug, and you want to check them before installing, or you want to check how your current spark plug is functioning, knowing the actual gap between both electrodes is important.

Tips

• Generally, most vehicle gap size is often between 0.028-06 inches (0.15cm). Check your owner’s manual guide or visit the nearest store to confirm.
• If your engine is the modified type, that means it requires smaller gap settings to give the power you’re putting through your engine. Normally, the rule states that “the more the power, the smaller the gap”

(2) Choose Suitable Spark Plug Gap Tool

There are different tools you can use to gap your spark plugs, some of which are more suitable for recent spark plugs, they occasionally contain sensitive precious metals. The majority of the measuring instruments have a flat edge, which you can use to bend the spark plug’s bottom electrode to slightly alter the gap.

Tips

• Coin Style Measure: This is the least expensive option. It works by dragging the edge of the coin through the gap until it stops. The edge is imprinted with a ruler-like pattern that indicates the edge’s thickness at that location. When you are using it, you need to be more careful because it has the potential of unintentionally expanding your spark plug gap.
• Wire Coin Gap: The wire coin gap functions similarly to the conventional coin-style gap except that it has different wire measurements with variable lengths on the edge surrounding the coin.
• Blade-Style Gap: It is in the blade form, an adaptable instrument, it has a pocket knife shape, and features several blades with different widths with some ends with wires and some without that you can put into the gap to measure your spark plug gap. If you want to measure wider gaps, you can combine 2 or more blades.

(3) Clean The Spark Plug

The spark plug will still be in good shape after you remove it from the box. But if it’s a spark plug that you have been using, it’s advisable to always clean it with a clean cloth. When spark plugs are old, there’s the possibility that you’ll see some whitish soot on the contact points, make sure you clean them for you to have the most accurate reading.

Tips

• If the spark plugs are dirty, apply a bit of quick-drying alcohol on the contact points and clean them thoroughly.
• Use an air compressor-mounted sand-filled bag. It is a spark plug cleaning tool that you can use to clean your spark plug’s electrodes.

(4) Measure The Gap By Passing The Tool Through The Electrodes

For you to find the measurement, place the appropriate blade or wire on your gap tool between the plug’s electrode tips, or run a coin between the electrodes.

PART B- Adjust The Gap

(1) Check If There’s A Need To Adjust The Gap

For you to determine if the gap of your spark plug is wide, place the gap-checking tool between the tip and the electrode. If it passes through without having contact with the tip and center electrode, it means your spark plug is too wide. If it does not fit between the tip and the center electrode, it indicates that the gap is too small you need to widen the gap a bit. But if it fits well to your actual measurement, it means you can install the spark plug to your vehicle.

Tips

• Mostly, you do not need to gap most spark plugs and iridium spark plugs before installing them. However, if your engine is custom-modified, you might need to install them with different gap sizes and adjust them accordingly.

(2) Adjust The Bottom Electrodes With The Tool

Bend the electrode of the spark plug gently while you hold and face the electrode toward the floor. Gently bend it inward if the gap is too wide, and vice-versa if the gap is too small.

Tips

• Be very careful while bending the electrode in or out, they are breakable, and any fracture will cause a misfire so do not apply too much pressure. Also, don’t bend more than a few (.02) fractions of an inch.
• If you find it difficult to use the tool to adjust the gap, carefully bend and adjust it on a flat surface like a table by applying a little pressure on the electrode.

(3) Measure The Gap Again And Adjust Accordingly

Try as much as possible not to have contact with the center electrode so that you won’t cause any damage to the core.

(4)Do It Gently

Bend the electrode a bit by applying a bit of pressure on the electrode.

How To Reinstall Your Gapped Spark Plugs

1. Use a rag to clean the dirt that might be in the hole of the cylindrical block.
2. First install your spark plug by hand and turn it clockwise not less than two times.
3. Further tighten it with your socket wrench
4. Lastly, connect the ignition coil or wire connector.

FAQs

What Are The Consequences Of A Narrower Spark Plug Gap?

When your spark plug gap is narrower, it will give a weak spark  which will be insufficient to ignite the air-fuel mixture in your internal combustion engine.

What Is The Outcome Of A Spark Plug With A Wider Gap?

When your spark plug gap is wider, it makes your engine hesitate to start.

When I Buy A New Spark Plug, Do I Need To Adjust The Gap Settings?

Your engine is what determines whether you need to adjust your new spark plug or not. When you buy a spark plug and you realize that the pre-gapped size is recommended for your engine, you can install it directly. But if it’s not recommended for your engine, adjust it.

Conclusion

The power of the spark plug gap cannot be underestimated when it comes to providing sparks that are necessary to power your engine. Meanwhile, you have to be more cautious and adhere to all the instructions in this guide whenever you want to gap your spark plugs.