2020 Ford F-350 Super Duty: Spark Plug Type & Gap

Quick Reference: 2020 Ford F-350 Spark Plug Specifications

Why the Right Spark Plug Matters

Choosing the correct spark plug is critical for engine performance, fuel economy, and longevity. It's not just about finding a plug that screws in; factors like heat range and electrode material are vital.

• Heat Range: This determines how quickly the plug dissipates heat from the combustion chamber. A plug that's too "hot" (dissipates heat slowly) can cause pre-ignition or detonation. A plug that's too "cold" (dissipates heat too quickly) can lead to carbon fouling, causing misfires. For the 2020 F-350 engines, using the OEM-specified heat range is essential for optimal performance.

• Electrode Material: The center electrode material dictates the plug's lifespan and performance.

  • Iridium: The 2020 F-350 comes from the factory with iridium-tipped spark plugs. Iridium is an extremely hard, precious metal with a very high melting point, making it ideal for modern high-energy ignition systems. It allows for a very fine center electrode, which improves ignitability and performance while providing a long service life, typically around 100,000 miles.
  • Platinum: A good alternative to iridium, double platinum plugs also offer long life and consistent performance, though they may not last quite as long as iridium.
  • Copper: While once the standard, copper plugs have a much shorter lifespan (20,000-30,000 miles) and are not recommended for the high-demand ignition systems in the 2020 F-350.

How to Gap a Spark Plug

Even though most modern iridium plugs come pre-gapped, it's crucial to verify the gap before installation. Shipping and handling can easily close the delicate gap.

1. Use the Right Tool: Use a dedicated spark plug gapping tool. A feeler gauge or wire-style gauge is best. Avoid the old "coin-style" disc gappers, as they can put pressure on the fine-wire iridium electrode and damage it.
2. Check the Gap: Gently slide the correct wire or feeler gauge between the center and ground electrodes. It should slide through with slight resistance. If it's too loose or won't fit, the gap needs adjustment.
3. Adjust Carefully: To adjust, gently bend the ground strap (the L-shaped electrode) by lightly tapping it on a hard surface to close the gap or using the prying portion of your gapping tool to open it. Never pry against or put pressure on the center electrode.

Replacement Procedure Tips for 2020 F-350

The 6.2L and 7.3L engines in the 2020 F-350 both use a modern Coil-On-Plug (COP) ignition system, which simplifies the replacement process compared to older distributor-based systems.

• Coil-On-Plug Removal: Each spark plug has its own ignition coil mounted directly on top. To access the plug, you must first remove the coil. Typically, this involves disconnecting the low-voltage electrical connector and removing a single bolt (often 7mm or 8mm) holding the coil to the valve cover. Gently twist and pull the coil straight up to remove it.

• The Anti-Seize Debate: The question of whether to use anti-seize on the spark plug threads is a hot topic. Motorcraft, Ford's own parts brand, specifically advises against using anti-seize on its modern plugs. The plugs feature a special plating that prevents seizing and provides the correct lubricity for accurate torquing. Applying anti-seize can act as a lubricant, leading you to over-torque the plug, which can stretch the threads and damage the cylinder head.

• Dielectric Grease: While you should skip the anti-seize, applying a small amount of dielectric grease to the inside of the ignition coil boot is highly recommended. This prevents the boot from sticking to the spark plug porcelain over time, makes future removal easier, and helps seal out moisture that could cause a misfire.

• Torque Wrench is a Must: Always use a torque wrench. Over-tightening can damage the cylinder head, while under-tightening can allow the plug to back out, causing a loss of compression and potential damage.

Known Issues

Fortunately for 2020 F-350 owners, the infamous Ford 3-valve Triton engine issues are a thing of the past. Those engines (like the 5.4L V8) used a problematic two-piece spark plug design that was prone to breaking off in the cylinder head during removal. The 6.2L and 7.3L engines in the 2020 models use a conventional, one-piece spark plug design, eliminating this major headache. There are no widespread, common issues related to spark plug replacement on these modern Ford V8s.

Need plugs replaced? Find a shop on Repairius.