NGK 7866 Spark Plug

NGK Laser Iridium Spark Plug 7866 Overview

NGK Laser Iridium Spark Plug 7866 is an OE-style ignition component built for precise spark delivery and long service life. It uses an iridium center electrode tip, a nickel ground electrode, and a 0.040 in. pre-gap for the applications listed below.

Compatible with select Jaguar and Land Rover vehicles, including Jaguar XF, XJ8, XK8, and Land Rover Range Rover Sport applications, this spark plug is specified for factory-style replacement service. The NGK Laser Iridium Spark Plug line is designed around OE fit, consistent ignition performance, and durability across a wide range of domestic and import vehicles.

Key Features

• Laser iridium center electrode tip for stable spark performance
• Nickel ground electrode with standard tip design and standard configuration
• 0.040 in. pre-gap for listed Jaguar applications; select Land Rover applications specify 0.039 in.
• 14 mm thread diameter, 0.75 in. reach, and 5/8 in. hex size
• 5000 ohm resistance and flat seat design
• OE-style spark plug from NGK, part number 7866 / IFR5N10

Detailed Description

NGK 7866 is a Laser Iridium spark plug engineered for vehicles that call for a factory-equivalent ignition service part. The iridium center electrode tip supports consistent firing, while the copper core and nickel ground electrode help maintain dependable heat transfer and ignition stability. With a non-removable nut terminal and standard ground configuration, this plug follows the OE-style specifications used in the listed Jaguar and Land Rover engines.

This part cross-references Carlson 7866 for the same application. It is a direct search match for drivers looking for NGK 7866 spark plug replacement, IFR5N10 spark plug, or an OE replacement spark plug for Jaguar XF, Jaguar XJ8, Jaguar XK8, and Land Rover Range Rover Sport service.

What It Helps Address

• Engine misfire caused by worn or fouled spark plugs
• Hard starting from weak or inconsistent spark output
• Rough idle and uneven combustion
• Reduced throttle response from degraded ignition performance
• Maintenance replacement for OE service intervals on listed Jaguar and Land Rover models

Installation Notes and Tips

Verify the vehicle application before installation and confirm the specified gap for your engine. Listed fitments include 0.040 in. gap for many Jaguar applications and 0.039 in. gap for select Land Rover applications. Use the correct torque procedure for the cylinder head material, and inspect ignition coils and boots during service to avoid repeat misfire concerns.

• Fits 2009-2010 Jaguar XF, N/A
• Fits 2005-2009 Jaguar Super V8, N/A
• Fits 1998-2009 Jaguar Vanden Plas, N/A
• Fits 1998-2009 Jaguar XJ8, N/A
• Fits 2000-2009 Jaguar XJR, N/A
• Fits 2007-2009 Jaguar XK, N/A
• Fits 2001-2009 Jaguar XKR, N/A
• Fits 2006-2009 Land Rover LR3, N/A
• Fits 2006-2009 Land Rover Range Rover, N/A
• Fits 2006-2009 Land Rover Range Rover Sport, N/A
• Fits 2007-2008 Jaguar S-Type, N/A
• Fits 2004-2006 Jaguar S-Type, N/A
• Fits 1997-2006 Jaguar XK8, N/A
• Fits 2004-2005 Jaguar XJR, N/A
• Fits 2005 Land Rover LR3, N/A
• Fits 2003-2004 Jaguar XKR, N/A
• Fits 2003 Jaguar S-Type, N/A
• Fits 2000-2003 Jaguar Vanden Plas, N/A
• Fits 2000 Jaguar XKR, N/A
• Fits 1999 Jaguar XJR, N/A
• Fits 1993-1997 Jaguar Vanden Plas, N/A

Quality Assurance

NGK is a long-established OE supplier and manufacturer with broad coverage across automotive, motorcycle, marine, and small engine ignition applications. Part number 7866 is built to OE-style standards for durability and operational performance in the listed vehicles.