HKS 50003-M35iL Super Fire Racing Iridium Spark Plug Long Reach ISO HR7 14mm

Vehicle Fitment

• Universal Fit - Compatible with any vehicle requiring a 14mm x 26.5mm long-reach ISO-type spark plug with Heat Range 7 (NGK equivalent)

Fitment Notes

• This is a universal spark plug sold individually - confirm your engine requires a 14mm x 26.5mm long-reach thread before ordering
• The "L" suffix denotes Long Reach (26.5mm thread length); do not substitute for standard-reach 50003-M35i (19mm thread)
• Heat Range 7 (NGK equivalent) is suited for mildly to moderately tuned engines; step up to M40iL or M45iL for higher boost applications

Features

• 0.6mm Iridium Alloy Center Electrode reduces required voltage and delivers sharper, more consistent spark ignition
• Outer electrode features a square platinum chip that improves wear resistance and boosts ignition efficiency when paired with the iridium center
• Short-type anti-vibration outer electrode reduces mass and resists vibration at high RPM for stable long-term performance
• Tapered outer electrode tip design maximizes combustion chamber space volume for improved flame propagation
• Anti-carbon build-up construction keeps combustion chambers cleaner over extended service intervals
• High iridium melting point of 2,454°C withstands elevated compression and minor detonation without electrode degradation
• Nickel-coated housing prevents corrosion and premature housing deterioration
• Long-reach thread design provides direct compatibility with deeper-threaded cylinder head applications

Specifications

• Part Number: 50003-M35iL
• Series: Super Fire Racing M-Series
• Type: Long Reach (ISO)
• Heat Range: 35 (HKS) / NGK #7 equivalent
• Center Electrode: 0.6mm Iridium Alloy
• Outer Electrode: Platinum Square Chip
• Thread Size: 14mm x 26.5mm
• Wrench Size: 16mm
• Sold: Individually (per piece)

Included Components

• 1x HKS Super Fire Racing M35iL Iridium Spark Plug (Long Reach ISO Type)

Product Description

The HKS Super Fire Racing M35iL (50003-M35iL) is the long-reach variant of HKS's flagship M-Series iridium spark plug, engineered for engines with deeper cylinder head thread depths requiring a 14mm x 26.5mm plug. It delivers the same core iridium-platinum electrode technology as the standard M35i but is specifically built for long-reach applications where a standard 19mm plug would not seat correctly. With a heat range equivalent to NGK #7, it is well suited for mild to moderately tuned street engines.

The combination of a 0.6mm iridium alloy center electrode and platinum-tipped outer electrode ensures lower ignition voltage requirements, reduced misfires, and improved combustion efficiency over OEM plugs. The shortened anti-vibration outer electrode further stabilizes spark delivery under sustained load. Plugs are sold individually - order the correct quantity to match your engine's cylinder count.