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NGK 6668 Spark Plug
| Brand | NGK 6668 |
|---|---|
| Resistance | 5000 |
| Ground Electrode Tip Design | Standard |
| Ground Configuration | Standard |
| Ground Electrode Core Material | Nickel |
| Electrical Terminal Type | Non-removable nut |
| Center Electrode Core Material | Copper |
| Center Electrode Tip Material | Nickel |
| Pre-Gap Size | .036 |
| Ground Electrode Quantity | 1 |
| Hex Size | 5/8 |
| Insulator Height | 50.50 |
| Manufacturer Heat Range | 6 |
| Seat Type | Flat |
| Reach | 26.5 |
| Thread Diameter | 14.00 |
| Part Number | Lfr6a |
| Stock Number | 6668 |
| Fits | — |
OE supplier heritage. Built by NGK, a long-time original equipment spark plug manufacturer.
Copper core design. Helps promote efficient ignition performance and durability.
Standard configuration. A straightforward spark plug setup with nickel electrode materials.
Cross-references NGK 6668, 22401-AR716 and 94702-00427 for the same application. See all 4.
NGK V-Power Spark Plug 6668 Overview
NGK V-Power Spark Plug 6668 is a copper-core, nickel-tipped spark plug built for stable ignition performance and consistent electrical conductivity. It uses a 0.036 pre-gap, 5,000 ohm resistance, and a flat seat design for applications that call for this exact specification.
As part of the NGK V-Power Spark Plug line, this plug reflects NGK’s OE-focused approach to ignition components for domestic and import vehicles. The V-Power design is aimed at dependable spark delivery and reliable combustion in everyday driving conditions.
Key Features
- Part number 6668, NGK LFR6A
- Copper center electrode core for efficient heat transfer
- Nickel center and ground electrode tip materials
- Standard ground electrode configuration with one ground electrode
- 5,000 ohm resistance for ignition system noise control
- Pre-gapped to .036 for specified applications
- Flat seat, 14.00 mm thread diameter, 5/8 hex size
- Manufacturer heat range 6
Detailed Description
NGK 6668 is a V-Power spark plug engineered around a copper core and nickel electrode construction to support consistent spark delivery and dependable service life in the correct application. The standard ground electrode design and flat seat configuration make it a direct-spec replacement for vehicles that require NGK LFR6A dimensions and heat range 6. For drivers searching for an NGK spark plug 6668 for Honda Civic or other specified vehicle applications, this plug provides the core specifications needed for accurate ignition service.
This part cross-references Monroe Shocks & Struts (e.g., 172286, 182286) for the same application.
What It Helps Address
- Misfires caused by worn or incorrect spark plugs
- Hard starting from weak ignition output
- Rough idle related to degraded plug performance
- Reduced combustion consistency under normal driving
- Ignition noise concerns where 5,000 ohm resistance is specified
Installation Notes and Tips
Verify the required thread diameter, reach, seat type, heat range, and pre-gap before installation. Use the vehicle service specification for gap verification and torque, and confirm the NGK LFR6A cross-reference before replacing plugs in Honda Civic or other listed applications. Clean the plug seat area and inspect ignition components during service to help ensure proper operation.
Quality Assurance
NGK is a long-standing OE supplier and manufacturer of spark plugs for domestic and import vehicles in North America. Its manufacturing and distribution network supports OE-style standards for durability and operational performance across a wide range of automotive applications.
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