NGK 4742 Spark Plug

NGK Laser Iridium Spark Plug 4742 Overview

NGK Laser Iridium Spark Plug 4742 is built for drivers who want precise ignition performance and OE-style fitment details in a compact, serviceable spark plug design. With an iridium center electrode tip, copper core, and 5,000 ohm resistance, this plug supports stable spark delivery for everyday driving and consistent engine operation.

Compatible With select vehicle applications that call for NGK KR8DI / 4742, including Honda Civic and other import applications where the specified thread, reach, and heat range match the original equipment requirement.

Key Features

• Laser Iridium design with an iridium center electrode tip for focused spark delivery
• Copper center electrode core for efficient heat transfer
• Nickel ground electrode core material with standard ground configuration
• 5/8 hex size, 12 mm thread diameter, and .75 reach
• Flat seat type with a .032 pre-gap size
• Manufacturer heat range 8 for applications requiring this specification
• Stud terminal type for the specified ignition connection
• NGK part number 4742, also identified as KR8DI

Product Details

NGK 4742 is a Laser Iridium spark plug engineered around the specifications listed by the manufacturer: 12 mm thread diameter, .75 reach, flat seat, 5/8 hex, and a 50.00 insulator height. The iridium tip helps maintain a precise firing point, while the copper core supports thermal control in the plug body. As part of NGK’s Laser Iridium line, this spark plug reflects the brand’s OE-focused approach and long-standing role supplying ignition components for domestic and import vehicles.

This part cross-references AMS Automotive 4742 for the same application. Search terms such as NGK 4742 spark plug, KR8DI replacement, and Laser Iridium spark plug for Honda Civic help identify the correct ignition component when the vehicle specification matches the listed dimensions and heat range.

Common Issues This Part Can Address

• Misfire caused by worn or inconsistent spark plug electrodes
• Hard starting related to degraded ignition performance
• Rough idle from an aging plug with excessive gap wear
• Reduced throttle response from weak spark delivery
• Service replacement needs for vehicles specified to use NGK KR8DI / 4742

Installation Notes and Tips

Verify the engine’s required thread diameter, reach, seat type, heat range, and terminal style before installation. Confirm the pre-gap specification against the vehicle service information, and inspect the ignition system for carbon tracking, oil fouling, or coil issues before fitting the new plug. For fitment-based searches, use phrases like NGK 4742 spark plug for Honda Civic or KR8DI spark plug replacement for import vehicles only when the engine specification matches.

Quality Assurance

NGK is a major OE spark plug supplier with more than 80 years of automotive experience, and this plug is produced to support original-equipment-level durability and performance standards. The brand’s North American manufacturing and distribution network supports consistent product availability and specification control.