AC Delco vs. NGK Spark Plug: Which One is Better?

The spark plugs are one of the most essential components in a gasoline engine. And when it comes to choosing spark plugs for your car, AC Delco and NGK are arguably the two most popular brands. Today, we will compare these two brands to find out which one is better.

Not all spark plugs are created equal. So, it’s important for any buyer to learn about the most common differences. This article will help you in deciding whether to go for NGK or AC Delco spark plugs.

The electrode design, availability, metal composition, and price are some of the most common differences between these two spark plug brands. Keep these things in mind on your next visit to the auto parts store.

Why Do You Need Spark Plugs?

Before comparing the two brands, you need to first understand what spark plugs do. Spark plugs are the main source of ignition inside your engine. Without them, an internal combustion engine won’t do anything – and won’t go anywhere.

You can find the spark plug attached to the vehicle’s cylinder head. In essence, these act like small bots of lighting. Though they are small in size, they operate through a somewhat complex process.

The process begins as soon as the driver cranks the engine, either by turning the key or pushing the start button. At that moment, the induction coil in the engine receives electricity from the car battery.

Closer to 45.000 volts of electricity travels to the spark plugs from the ignition coil, creating an arc of electricity across the two spark plug leads. This arc ignites the air-fuel mixture inside the cylinder, producing the power which makes your engine run.

AC Delco

AC Delco Spark Plug

Now that you know how spark plugs work, let us take a look at the two brands of interest today. Let’s start off by looking at AC Delco.

AC Delco is a well-renowned name in the automotive world. It is safe to say that spark plugs are the product that put them on the map. Nowadays, the company offers a range of spark plugs to suit all customer needs. Some of their most popular spark plug types include:

  • “Rapidfire” platinum spark plugs
  • Double platinum spark plugs
  • Double platinum “Finewire” spark plugs

Let us have a brief look through each of them and see what they have to offer.

“Rapidfire” Platinum Spark Plugs

When compared to the other competing spark plugs on the market, the Rapidfire spark plugs by AC Delco come with increased efficiency. Not only that, but they last longer too!

These spark plugs have a ribless insulator, which seals them tightly with the cylinder head. Not only that, but the platinum pad inside the tapered center wire electrode massively improves the plug’s firing efficiency.

Double Platinum Spark Plugs

The double platinum spark plugs by AC Delco take things one step further by including a dual platinum tip. Not only does this resist spark erosion, but it has anti-corrosive qualities as well.

When talking about corrosion, reducing corrosion was one of AC Delco’s main goals when creating this spark plug. As a result, it comes with a corrosion-resistant shell as well.

One of the most distinguishing features of the AC Delco double platinum spark plugs is the inclusion of an internal glass resistor. This offers a whole host of benefits, including reducing the radio frequency interference and controlling spark plug energy to increase the longevity of the product.

Double Platinum “Finewire” Spark Plugs

Designed to be used with modern vehicles, the AC Delco Finewire spark plugs can function perfectly with reduced system voltages. These provide a more focused ignition than the competition, leading to better ignitability.

The acceleration characteristics of these plugs are impressive, as are the cold-startup capabilities. If you own a vehicle that just came out, these spark plugs are worth taking a look at.


NGK spark plug

Next, let’s shift our attention toward the next spark plug manufacturer on our radar, which is NGK. This is one of the most recognized brands when it comes to spark plugs.

The history of NGK spark plugs runs all the way back to 1937. Since then, this Japanese manufacturer has been a leading force behind spark plug innovation.

Similar to AC Delco, NGK has some great products up its sleeve as well. A few of the best-selling ones include,

  • NGK Iridium spark plugs
  • Nickel spark plugs
  • OE-Style spark plugs

NGK Iridium spark plugs

The Iridium spark plugs are one of NGK’s signature products. Designed for performance cars, these spark plugs are the ones to go for if you want to get the most power out of your engine.

The NGK iridium spark plugs have a high melting point, making them the perfect choice for powerful engines that get insanely hot. The fine iridium tip at the end guarantees a stable spark no matter how fast the engine runs.

Worried about corrosion? The NGK iridium spark plugs have got you covered in that aspect as well. Their trivalent metal plating makes it corrosion-resistant and also provides commendable anti-seizing properties.

Nickel Spark Plugs

The nickel spark plugs by NGK come from the factory with a core made up of 98% pure copper. This makes the plugs more reliable while also increasing the heat dissipation characteristics.

A special feature of these spark plugs is their v-groove center electrode. With this special design, NGK achieves two main benefits. One is reducing quenching, while the other is improving the ignitability.


Now that you know all about NGK and AC Delco, it’s time for us to learn more about the differences between the two.


You are bound to come across NGK spark plugs more often than AC Delco ones on your visits to the local auto parts store. This increased availability may sway some vehicle owners in the direction of NGK.

However, if you live in North America, you might not face this issue at all. AC Delco has a widespread supply chain across its native region.

Electrode Design

NGK and AC Delco follow somewhat different approaches when designing their electrodes. Both designs have plenty of different benefits, as well as several drawbacks.

The most noticeable design difference between the two models is the size of the electrode itself. NGK fits their plugs with a smaller electrode, which gives them better ignitability. Not only that, but it makes these plugs last longer too.

On the other hand, the electrode of AC Delco plugs is larger in size. This allows the AC Delco plugs to have better heat dissipation characteristics when compared to the ones made by NGK.


The composition of materials is another difference between these two spark plug types. AC Delco uses a high platinum alloy to create its spark plugs, while NGK typically uses nickel alloy in its production.


Price is one of the main things you should pay attention to when purchasing spark plugs. In a way, this ties into the previous point we discussed as well.

You see, platinum is more expensive than nickel, which makes AC Delco spark plugs generally more expensive than NGK products. However, the price may vary depending on the specific model you go for.

Maintenance Tips To Make Spark Plugs Last Longer

On average, spark plugs last between 30,000 to 50,000 miles. Yet, there are some tips you can follow to extend their life.

Choose The Right Spark Plug

This entry might seem obvious, but not choosing the correct style of spark plugs is a crime most vehicle owners are guilty of committing.

For example, high-performance engines require spark plugs that can withstand intense heat. On the other hand, spark plugs with good heat dissipation are the best choice for normal engines.

Remember to pay attention to factors like these before spending money on a fresh set of spark plugs.

Clean The Plugs Periodically

Just like the other parts of your car, the spark plugs need a good cleaning every once in a while as well. In order to clean them, first you have to extract them from the engine. Use a spark plug socket for this task.

Once the plugs are out of the car, give them a thorough cleaning using some carburetor cleaner or thinner. You can use either a nylon brush to remove all the dust and residue from the spark plug surfaces before inserting them back into place.

Keep The Mounting Area Clean

It is important to keep the area where the spark plug mounts to the engine clean too. If not, dirt accumulation in this area may lead to spark plug misalignments. You can use thinner or oil to remove residue from this area.

NGK vs AC Delco – Which One To Get?

Ultimately, the choice between NGK and AC Delco spark plugs comes down to personal preference. Both types have their own pros and cons, as well as some unique features. However, if you are looking to purchase a set of spark plugs that offer the best value for money, NGK is the brand to go for.

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Who Worked on This?



I'm the guy responsible for ensuring that every blog post we publish is helpful for our reader.

Mahir Ahmed


I'm the guy responsible for ensuring honest, informative, accurate and helpful guide to the reader.

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