NGK 7516 Spark Plug

NGK Iridium IX Spark Plug 7516

NGK Iridium IX Spark Plug 7516 is built for drivers who need consistent ignition performance in older Chevrolet and GMC applications. With an iridium center electrode, copper core, and tapered seat design, this plug supports stable combustion and reliable starts across a wide range of classic truck and car fitments.

The NGK Iridium IX Spark Plug line focuses on precise ignition characteristics and OE-level manufacturing standards. Part number 7516, also identified as YR5IX, is a direct replacement option for many Chevrolet C10, C20, K10, and GMC K2500 applications where the specified heat range, reach, and gap must match the vehicle’s original requirements.

Key Features

• Iridium center electrode tip material for consistent spark delivery
• Copper core center electrode for efficient heat transfer
• Nickel ground electrode with taper-cut tip design
• 5,000 ohm resistance for ignition system compatibility
• 14 mm thread diameter, 0.46 reach, and tapered seat type
• Pre-gapped at .040 for installation reference
• NGK part number 7516 / YR5IX

Detailed Description

NGK 7516 is an Iridium IX spark plug engineered for older domestic vehicles that call for a tapered-seat plug with a 5/8 hex and a 5 heat range. The iridium firing tip helps maintain a focused spark, while the copper core supports heat dissipation under sustained engine load. This makes it a practical choice for classic Chevrolet and GMC trucks, vans, and passenger cars that rely on accurate ignition timing and the correct plug specification.

Compatible With applications include 1969-1989 Chevrolet C10, C20, K10, P30, and El Camino models, plus 1969-1989 GMC C2500, K2500, P3500, and Jimmy applications listed in the fitment data. This part cross-references DENSO Auto Parts 5030 and Carlson 7516 for the same application.

What It Helps Address

• Hard starting caused by worn or inconsistent spark plugs
• Misfire concerns tied to incorrect plug heat range or gap
• Rough idle in older Chevrolet and GMC ignition systems
• Reduced combustion stability under load
• Maintenance issues from aging conventional plugs

Installation Notes and Tips

Verify the vehicle’s required gap, heat range, and seat type before installation. Fitment notes in the catalog include both 0.035-inch and 0.045-inch gap references depending on year, engine, and emissions configuration, so confirm the exact application for your Chevrolet or GMC model before use. Check that the ignition system matches the plug specification, especially on 1975-era vehicles where HEI compatibility is specifically noted in the fitment data.

• Fits 1976-1989 Chevrolet P20, N/A
• Fits 1975-1989 Chevrolet P30, N/A
• Fits 1985-1988 Chevrolet G30, N/A
• Fits 1985-1986 Chevrolet C10, N/A
• Fits 1985-1986 Chevrolet K20, N/A
• Fits 1985-1986 GMC C1500, N/A
• Fits 1981-1986 GMC C3500, N/A
• Fits 1979-1984 GMC K2500, N/A
• Fits 1970-1974 Chevrolet Camaro, N/A
• Fits 1970-1974 Chevrolet Corvette, N/A

Quality Assurance

NGK is a major OE spark plug supplier in North America with more than 80 years of automotive manufacturing experience. Part number 7516 is produced to support original-equipment standards for durability and operational performance across domestic and import ignition applications.