NGK 373 Spark Plug

NGK Laser Iridium Spark Plug Overview

The NGK Laser Iridium High Ignitability Spark Plug 373 is engineered for reliable ignition performance in Subaru Legacy vehicles. Designed with advanced materials and precise specifications, this spark plug supports efficient combustion and consistent engine operation.

• Part Number: 373 (Silfr6b8)
• Compatible with Subaru Legacy models
• Iridium center electrode for enhanced durability
• Projected square platinum ground electrode for high ignitability
• Standard ground configuration with nickel core electrode
• Non-removable nut electrical terminal type
• Pre-gap size of 0.032 inches for optimal spark
• Flat seat type with 14mm thread diameter and 26.5mm reach
• Manufacturer heat range 6 for balanced thermal performance

Features of the Laser Iridium High Ignitability Spark Plug

The NGK Laser Iridium High Ignitability Spark Plug line is designed to provide precise ignition and long service life. This product line incorporates iridium and platinum materials to improve spark efficiency and electrode durability. The projected square platinum ground electrode enhances ignitability, while the copper core center electrode ensures excellent conductivity. These features contribute to stable combustion and reduced misfires in compatible engines.

Technical Specifications and Benefits

This NGK spark plug features a 5000 ohm resistance to reduce electrical noise and protect vehicle electronics. The center electrode is made of iridium, known for its high melting point and wear resistance, while the ground electrode uses a nickel core with a projected square platinum tip to improve ignition reliability. The pre-gap size of 0.032 inches is factory set to optimize spark performance. The spark plug’s flat seat and 14mm thread diameter with a 26.5mm reach ensure proper fitment in Subaru Legacy engines requiring heat range 6 plugs.

Applications and Problem Solving

• Compatible with Subaru Legacy models requiring NGK Silfr6b8 spark plugs
• Helps reduce engine misfires and rough idling
• Improves cold start performance and throttle response
• Supports consistent combustion for better fuel efficiency
• Minimizes electrode wear for extended service intervals

Installation Notes and Tips

When installing the NGK Laser Iridium High Ignitability Spark Plug 373, ensure the spark plug gap is checked and adjusted if necessary, although it comes pre-gapped at 0.032 inches. Use a torque wrench to tighten the spark plug to the manufacturer’s specifications to avoid damage to the threads or seat. The non-removable nut terminal type requires compatible ignition wiring connectors. Inspect the spark plug hole for debris before installation to ensure proper seating.

Quality Assurance and Warranty

NGK spark plugs are manufactured to strict quality standards to ensure reliable performance and durability. The Laser Iridium High Ignitability Spark Plug 373 undergoes rigorous testing for resistance, heat range, and electrode integrity. While specific warranty details are not provided here, NGK products typically come with manufacturer-backed quality assurance to support their use in Subaru Legacy vehicles.