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What Are The Best Spark Plugs For A Ford Mustang?

Written By: Josh Honeycutt

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To perform at its peak, your Mustang needs to have spark plugs that are in good condition and up to the task. Make sure you select a set that is going to last and can handle the power your Mustang is putting out.

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Choosing the right spark plug for you Ford Mustang requires a bit of knowledge about the plugs you're currently using, as well as the performance level of the car. When finding the best plug for your application, these are a few things you'll need to consider.

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Facts About Mustang Spark Plugs 

Ford Motorcraft Spark Plug
  • Factory plugs are used for their durability and emissions qualities
  • Proper heat range for your Mustang is important to remember while choosing a spark plug
  • A larger spark plug gap is desired in a naturally aspirated Mustang, but a smaller gap is desired in a forced induction engine
  • Spark plug electrodes are made using iridium, platinum, silver, and gold, which causes the electrodes to last longer and created a consistent spark kernel

One of the most often overlooked items on the Ford Mustang is the spark plug. Most Mustang owners don’t give their spark plug selection a second thought, but this can end up a costly mistake. Ford rolled the stock 4.6 engines out with Motorcraft platinum tip spark plugs. These plugs are gapped from Ford’s factory at .055 inches. In recent years, many after market companies have researched and developed better spark plugs. These plugs allow for a more complete and efficient burn. 

Are the Mustang’s factory spark plugs good?

Stock Mustang Spark Plugs

The factory plug was mainly used because of its durability and emissions qualities. Ford was required to hit 50,000 miles for the emissions warranty required by the federal government. The factory plugs work quite well on stock and mildly modified cars. However, there are some gains to be made through the aftermarket. There are also situations where plugs with different heat ranges are needed.

What are spark plug heat ranges?

The heat range is the actual temperature at the tip of the electrode of the plug in a running engine. The heat range does not affect the temperature of the combustion chamber directly. However, the heat from the combustion chamber can cause the temperature of the electrode to rise. Spark plugs with a lower heat range are set to be “colder”, and vise-versa.

The Importance of the Proper Heat Range

It is important to choose a spark plug with the proper heat range for your Mustang. For example, with forced induction, a “colder” spark plug should be used. This is due to the increase in pressure inside the combustion chambers. Using a spark plug with a higher heat range will cause detonation or “pinging”. This is also the case in high combustion engines.

Spark Plug Gapping Explained

The spark plug gap is the area between the ground strap and the electrode. This is where the spark jumps from the electrode to run to ground, lighting the air fuel mixture in the combustion chamber. In naturally aspirated Mustangs, a larger gap is desirable as it provides a “fatter” spark. In forced induction engines, just the opposite is true. The gap must be reduced because of the increased turbulence and pressure in the combustion chamber. If not, the spark could be blown out causing a misfire.

Different Spark Plug Material

Aftermarket Spark Plug Tip

The primary change in spark plug material in recent years has been in the electrode of the plug. In the past, the electrodes were made of nickel, or copper. These materials eroded quickly with in town driving, and were less than desirable at the track.

Modern aftermarket companies use far more durable materials for the electrode. These materials include iridium, platinum, silver and even gold. The primary advantage being they last longer and produce a more consistent spark kernel. This results in better fuel economy and better throttle response.

Aftermarket Options For Mustangs

NGK is one of the most popular aftermarket spark plug producers. They offer a great iridium spark plug for the mustang, with noticeable gains in off idle throttle response. These can be picked up for around $70. The stock Ford Motorcraft plugs can be had for around $30. The E3 spark plugs resale for roughly $50 and use a nickel alloy electrode.

What spark plugs should I put in my Mustang?

Choosing which comes down to your needs—a stock Mustang will benefit from an upgraded plug, but will not need the most extreme options available. High horsepower applications certainly want to consider a high-quality plug to complement their other mods. Skipping out on a quality set of plugs could damage your motor and cause significant repair costs.

All things considered, choosing the right spark plug for your Mustang comes down to what modifications you currently have, and what you plan on doing in the near future. With all the options out there, it’s easy to jump at the first spark plug with the most promises. However, the best spark plug is the one that suits your engine with the right heat range, and gapped correctly.