2014 Ford F-350 Super Duty: Spark Plug Specifications

Quick Reference: 2014 F-350 Spark Plugs

Note: The 2014 F-350 Super Duty was only available with the 6.2L "Boss" V8 gasoline engine or the 6.7L "Power Stroke" V8 diesel engine. Diesel engines do not use spark plugs. The specifications in this article apply only to the 6.2L V8.

Why the Right Spark Plug Matters

Using the correct spark plug is critical for engine performance, fuel economy, and longevity. It's not just about finding a plug that threads in; the engineering behind it matters.

• Heat Range: This is the most critical factor. The heat range determines how quickly the spark plug tip dissipates heat. A plug that is too "hot" (dissipates heat slowly) can lead to pre-ignition (detonation), which can cause severe engine damage. A plug that is too "cold" (dissipates heat too quickly) can develop carbon fouling, leading to misfires. The OEM-specified Motorcraft plug is designed for the precise heat range required by the 6.2L V8.
• Electrode Material: The material of the center and ground electrodes determines the plug's lifespan and performance. The OEM Motorcraft SP-526 plug for the 6.2L V8 is a fine-wire iridium plug.
  • Iridium: An extremely hard, dense precious metal, iridium allows for a very fine center electrode, which lowers the voltage required to create a spark. This provides a more consistent, powerful spark and offers the longest service life, typically around 100,000 miles.
  • Platinum: Another long-life material, often used on the ground electrode in "double platinum" plugs. It offers excellent durability but is generally second to iridium in terms of performance and lifespan.
  • Copper: Standard on older vehicles, copper plugs have a large-diameter electrode and a much shorter lifespan (typically 20,000-30,000 miles). While inexpensive, they are not recommended for the 2014 F-350's ignition system, which is designed for a fine-wire iridium plug.

How to Gap a Spark Plug

Even when you buy pre-gapped plugs, it's essential to verify the gap before installation. A small drop during shipping can easily change the measurement.

1. Use the Right Tool: A wire-loop or feeler gauge tool is recommended for fine-wire iridium and platinum plugs. Avoid the old-style "disc" or "ramped" gauges, as they can put pressure on the delicate fine-wire electrode and damage it or break it off.
2. Measure Carefully: Slide the correct wire gauge (e.g., 0.044 inches for the middle of the spec) between the center and ground electrodes. You should feel very light drag. If the gauge is too loose or won't fit, the gap needs adjustment.
3. Adjust Gently: To close the gap, gently tap the end of the ground electrode on a hard, clean surface. To open the gap, use the small fork on your gapping tool to carefully bend the ground strap up, being sure not to touch or pry against the center electrode.

Replacement Procedure Tips for the 6.2L V8

The 6.2L V8 in the F-350 uses a modern coil-on-plug ignition system, with one ignition coil sitting directly on top of each spark plug. There are 16 spark plugs in this engine—two per cylinder (an upper and a lower).

• Coil-on-Plug Removal: To access the plugs, you must first remove the ignition coils. Unplug the electrical connector, then undo the single bolt (typically 7mm or 8mm) holding the coil in place. Gently twist and pull the coil straight up to remove it from the spark plug. A stubborn boot can be freed with a twisting motion or a specialized coil puller.
• Anti-Seize: The Great Debate: Motorcraft plugs, like the specified SP-526, come with a special metallic plating on the threads that acts as an anti-seize agent. For this reason, Ford officially recommends not using additional anti-seize compound. Applying anti-seize to these plated plugs can alter the torque reading, causing you to overtighten the plug, which can stretch the threads in the aluminum cylinder head. Always install these plugs on clean, dry threads.
• Dielectric Grease: While anti-seize is not recommended on the plug threads, applying a small amount of dielectric grease to the inside of the coil boot is a best practice. This grease is an insulator, not a conductor. It prevents voltage leaks, seals out moisture that can cause corrosion, and makes it easier to remove the coil in the future.
• Two Plugs Per Cylinder: Remember that this engine has 16 plugs. The lower set of plugs is more difficult to access, particularly on the passenger side. Be prepared with a variety of socket extensions and universal joints.

Known Issues

Fortunately, the 6.2L V8 in the 2014 F-350 does not suffer from the infamous two-piece spark plug breakage issue. That problem was specific to the earlier Ford 3-Valve modular engines (e.g., 5.4L V8 and 6.8L V10) from roughly 2004-2008. The 6.2L V8 uses a conventional, one-piece spark plug design (Motorcraft SP-526) that can be removed without the high risk of breakage associated with the older 3-valve engines.

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