NGK Standard Spark Plug LKR6E-9N 4-Pack — 12mm Thread, 26.5mm Reach, Copper Core

These NGK standard spark plugs combine proven materials and precise construction to serve a wide range of gasoline engines. Built with a copper core, pure alumina silicate ceramic insulator, trivalent plating, and corrugated ribs, each plug is designed to resist seizing, prevent flashover, and move heat away from the firing tip. The 12mm thread with a gasket seat, 26.5mm reach and a .035" (0.9mm) gap make them compatible with many late-model vehicles and routine maintenance tasks.

How do these spark plugs resist corrosion and seizing?

Corrosion and thread seizing are reduced by a trivalent metal plating that creates a durable protective layer on the plug body. The plating offers superior anti-corrosion performance compared with uncoated plugs, which helps during installation and removal, especially in high-moisture or road-salt environments.

• Trivalent plating for improved anti-corrosion properties
• Easier removal after extended service intervals
• Maintains consistent thread integrity under harsh conditions

What features improve ignition stability and prevent misfires?

Corrugated ribs on the insulator suppress flashover along the plug surface, helping keep the ignition energy focused at the electrode gap. A solid terminal and a 5K ohm resistor help reduce electromagnetic interference with vehicle electronics while supporting reliable firing characteristics.

• Corrugated ribs to prevent flashover
• Solid terminal construction for steady electrical contact
• 5K ohm resistor to limit radio frequency interference

How does the plug manage heat for consistent performance?

The combined copper core and a pure alumina silicate ceramic insulator provide efficient heat transfer away from the firing tip, helping the plug operate within its intended temperature range. This design supports stable combustion and helps the electrode maintain proper seating and gap over time.

• Copper core enhances heat removal from the electrode
• Alumina silicate ceramic insulator offers high strength and thermal conductivity
• Triple seals reduce the risk of combustion gas leakage

What size and fitment details should I confirm before buying?

These NGK plugs use a 12mm thread diameter with a gasket seat and a reach of 26.5mm (1.04"), so confirm your engine’s thread size and reach match to avoid interference with the combustion chamber. The hex size is 5/8" (16mm), and the factory gap is set to .035" (0.9mm), which can be rechecked and adjusted to the vehicle maker’s specification during installation.

• Thread size: 12mm; seat type: gasket
• Reach: 26.5mm (1.04"); hex: 5/8" (16mm)
• Terminal type: solid; gap: .035" (0.9mm)

Who is this for: The NGK 90410 LKR6E-9N 4-pack is suited for technicians, DIYers, and fleet maintenance teams replacing standard spark plugs on compatible gasoline engines. Choose these plugs when you need durable anti-seize protection, controlled heat transfer, and EMI suppression in a commonly used thread and reach size. Always cross-check with your vehicle’s service manual or parts catalog to confirm correct fitment before installation.