A Guide on How to Gap Spark Plugs Without Tool and With Tool

Spark plugs play a crucial role in most motor engines. A poorly-installed plug will cause engine misfires and impair your car’s speed as a result.

So whenever you spot a gap that should not be there, fixing it right away is a must!

But how to perform proper spark plug gap adjustments? Here is where we can be of help.

Our guide will discuss in detail how to gap spark plugs without tool and with tool – while also diving into the more suitable method for each case. Keep scrolling!

Why Should We Gap These Plugs?

The gapping degrees are decisive to your vehicle’s motor; a spark plug gap size either too big or too small will lead to a malfunctioning combustion chamber.

Also, since most drivers aim for low-quality plugs (instead of more sturdy ones) due to their low costs, the need to check the gapping is much more heightened than ever.

Never let their small-sized dimensions fool you about their importance. These fine-tuned elements are the key to engine performance!

While a typical spark plug operates upon numerous internal factors, one critical component is the gap.

Too much gapping means the center electrode cannot spark, resulting in zero combustion and the car’s failure to ignite.

Meanwhile, too narrow gaps give little room for air circulation around the ground electrode, which – you can guess – still leads to zero combustion process and faulty cylinder head.

In fact, most NGK and Bosch spark plugs on the markets today come pre-gapped. Provided that yours are from quality and trustable brands, there’s no need to be concerned about gapping. However, as their exorbitant prices have held people back, cheaper and lower-quality options are still thriving, which raises the need to double-check the gaps more than ever! 

Of course, you don’t always need to buy a spark plug gap tool for the fix.

The best scenario is to entrust your car’s fate to a renowned engine repair shop, since improper spark plug removal might cause more engine damage instead of solving the problem.

But if, for some reason, you cannot afford a quick visit to a mechanic service, then it’s alright to get into work yourself – with and without tools.

Before starting, though, make sure you have at least some decent/average skills for the task.

How to Gap Spark Plugs Without Tool

How to Gap Spark Plugs Without Tool

How to gap a spark plug without a tool? To gap spark plug without tool, loosen the plugs first, then bend the tip of your new plug to connect it with the cylinder block. Keep adjusting till the proper gap is established.

Once everything is set, place the electrodes back to their original positions, and repeat all these steps to other plugs.

1. Common Household Objects to Replace A Spark Plug Gapping Tool

Here are some common yet incredibly powerful household items for people with no special tool for the tasks: toothpicks, sandpapers, hairdryers, pliers, razor blades, keys, ballpoint pens, rubber bands, and plungers. Even your nails can be of great assistance!

Toothpick: Toothpicks are among the most common items, though we do not recommend them if the gaps are too tiny.

Sandpaper: Again, just like a toothpick, it does not work very well with small gaps. Only turn to it if there are no other devices available.

Hair Dryer: The best method for larger gaps, which gets things done within seconds. Steps needed for spark plug replacement and gap modifications are simple and fast, barely calling for any support.

Pliers: Inexperienced people might struggle with them for a bit. But once you get the hang, this approach is easier to practice – and not to mention, more accurate – than some other tools.

Razor Blade: Novices will fall in love right away, as it requires little to no skills. Still, one drawback lies in some minor engine issues the device might cause if you misstep a little.

Also, those looking for clean and professional gaps probably will not like razor blades very much.

Key: A quite trendy item! The secret is the blisters on the key’s outer edge, which paves the way for a nicer-cut hole.

Ballpoint Pens: Another classic! Although this method demands some patience and practice, trust us that these ballpoint pens will create miracles if you know how to do it right.

Rubber bands: Most seasoned drivers like to turn to them; simply stretch these bands wide till both ends meet, which establishes perfect gaps for you.

But what if your gap is bigger than average? Then try using more than one band.

Nails: Such approaches take less than a few minutes, which is a huge advantage.

Unfortunately, they are only suited to very small spark plug electrodes. Larger ones are more demanding, so simple nail-scratching will not work well for them.

Plungers: We admit that this solution does not receive much love from most customers – mainly due to the sheer complexity of the device itself.

However, if you are familiar with how these plungers operate, they are not half-bad! 

Also, in case the spark plug electrode opening is too small to accommodate the items introduced above, plungers can be a lifesaver.

2. Step-By-Step Instructions on Gapping Spark Plugs Without Tool

Aside from the items above, you might also want to use these to adjust spark plug gap:

  • Socket wrench
  • Ratchet
  • Extension pole
  • Screwdriver (preferably flat-headed)

Step 1. Turn off the engine. Then pick up your socket wrench to loosen the plug.

How to check the gap on a spark plug? We suggest you use some feeler gauges to get the exact measurement for the electrodes’ gapping.

But what if there are no gauges? How to measure spark plug gap then? Well, in that case, using your ears to spot the “tick” sounds is also advisable.

Step 2. Bring out the new plug, and bend its tip to make the spark plug connect with your cylinder block. Use your hands to keep them firmly in place.

Once done, measure the gap between this new plug and the car’s head surface.

After that, unwrap 0.22 inches off the feeler gauge before inserting it into that gap. Does it fail to slip in?

Then chances are the hole is way too small. By contrast, excessive force to squeeze the gauge in will leave your opening too big or broad. Try to maintain a nice balance!

Step 3. Once the gaps are measured, place the electrodes back to their original positions. Use the socket wrench to tighten them.

Step 4. Repeat all these steps for other vehicle plugs. Another alternative is to buy new sets of plugs-and-plays (PnP) coils, which eliminates the need for constant removal and re-installing.

Anyway, now is the time to start the car again! If it does not encounter any issues, you have successfully adjusted the spark plug gap without tool.

Otherwise, consider professional help when your engine struggles to operate.

3. Extra Tips to Gap Spark Plugs Without Tool

a. Pliers with flat jaws are better than curved ones.

b. During the gapping process, avoid wearing out the electrodes immediately. It will cause misfires and damage the engine’s linked plug holes.

Your gap will be too small as a result, unable to maintain appropriate compression.

c. Though the plugs might look properly gapped at the end, it doesn’t hurt to check them again.

This time, there’s no need to use a measuring tool; you can simply put a screwdriver’s tip (brush-type) atop the metal electrodes.

d. Tools like hanger wires, long-nosed pliers, and coat hangers can keep the screwdriver tips fixed on the spot. Gently use them to pull your hands away from the motor.

e. If the plugs have gaps, your screwdriver will produce high-pitched whistling noises – though you won’t hear it if the tip touches an electrode.

Hence, to apply this method, remember to remove your fingers from the screwdrivers first.

f. Likewise, no gaps mean no whistling noise. We recommend you clean or replace the electrodes.

g. After plug removal, do not forget to insert them back carefully into their respective holes. Never cross-thread these plugs; otherwise, leaks will transpire, reducing the vehicle’s compression.

How to Gap Spark Plugs With Tool

How to Gap Spark Plugs With Tool

Once you have decided on a proper feeler gauge, pass it through the ground electrodes and modify the spaces until it snugly fits in.

For adjustments, you may either push the electrodes towards each other (for narrowing) or out (for extending).

Step 1. Choose A Proper Feeler Gauge for Your Car 

There are numerous tool varieties to help you assess the plugs’ gapping, categorized into three main types:


These devices are often the cheapest. All you need to do is to run the coin’s edge through the gaps till it eventually reaches an endpoint. These edges are ruler-marked to help you with your measurements.

Older plugs will work pretty well with these tools. Be cautious, though; careless usage of these devices will actually widen the gap further.


They operate the same as standard coin-style. The only notable difference lies in the wire measures (with varying lengths) around the coins’ edges.


It’s apparently the most versatile option out of the three, built like mini pocket knives. These gauges feature blades of different widths – inserted within gaps to assess the electrodes’ spacing.

And what if your car has larger gaps than average? Simple: just use several blades at once.

Step 2. Clean These Plugs

Have you just pulled them out of their boxes? Then they should have a pretty nice shape at the moment.

However, should the plugs have been used in your vehicle for some time already, it doesn’t hurt to clean them thoroughly with some cloth.

The plugs can sustain some dirty whitish soot at contact points, which keeps you from accurate reading. Hence, make sure they are properly removed.

Step 3. Pass the Gauge Through The Ground Electrodes to Measure Their Spacing

Place the wire/blade between the plug’s electrode tips. Another approach is to pass the coins through these sections.

Now, let’s assess whether the gaps call for adjustments. Suppose the gauge passes through easily without brushing your electrodes; then the gaps are probably too wide.

On the other hand, ill-fitting gauges mean the spacing is a bit too restricted and demands some widening.

Anyways, keep adjusting till the tool fits just right (For iridium spark plugs, calibrated gapping tools might be more efficient than regular gauges). Only then will it be safe to install your plugs.

Step 4. Adjust The Base Electrodes

Bend them toward each other for gap narrowing – or in the opposite direction for increases. One thing to remember: never bend these electrodes for more than 0.2 inches, or their links will be broken.

A slightly misplaced pressure will destroy everything and cause misfires, so tread with caution!

If the tool struggles to fit the gaps, try bending it on flat surfaces (such as a table).

Furthermore, always avoid touching the center electrodes and risk damaging their core. You will have to buy new ones in that case – and trust us, they can be quite costly!

Tool Versus Without Tool – Which Method Is Better?

Both are fine if the plugs are pre-gapped. Otherwise, using tools is still safer.

Before your purchase, assess whether these plugs are pre-gapped. If the answer is yes, both methods work fine. Toolless approaches actually take much less time and save lots of effort!

Unfortunately, for non-pre-gapped ones, the lack of professional equipment can be quite risky. These plugs demand a certain level of expertise that not all drivers possess.

Wrong techniques may mess up the gaps even more!


Our article has delivered detailed instructions on how to gap spark plugs without tool and with tool.

Pre-gapped plugs can accommodate both methods pretty well. However, for non-pre-gapped options, it’s still much better to use proper gapping devices (or even better, turn to a professional automobile service!)

For more questions if any, feel free to write to Bryan’s Garage.

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