Every Mercury boat owner knows that reliable ignition is the heart of a smooth day on the water. The Mercury NGK LKAR7C9 Spark Plug (8M0135348) delivers just that—precise performance and OEM quality fused into a compact, marine-ready design tailored for 175–300 hp FourStroke and 450R 3.4 L V6/4.6 L V8 outboards (s/n 2B529482 and above).
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Key Features & Benefits:

• Perfect fit: OEM NGK LKAR7C9 drop-in replacement, no adapters or modifications needed.
• Pre-gapped to 0.9 mm: Matches factory specs for efficient combustion and smooth startup.
• Copper-core design: Promotes rapid heat transfer, reducing fouling risks on long runs.
• Trivalent plating: Marine-grade corrosion protection and anti-seize makes removal a breeze.

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Weighing only a few ounces, it tucks neatly in your toolbox and engine cowling. You’ll notice crisper throttle response and more consistent fuel economy when every cylinder fires on cue. Outfitted with a high-density ceramic insulator and corrugated ribs to prevent flashover, this spark plug stands up to salt spray and vibration.

When it’s time for routine maintenance, torque each plug to 10.8–14.5 lb·ft (aluminum) or 10.8–18 lb·ft (cast iron) for a leak-free seal.
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Swap in fresh 8M0135348 plugs during your seasonal tune-up, and enjoy dependable firing no matter where your voyage takes you.