Champion L77JC4 (821) Marine Spark Plug for Evinrude Outboard Engines

The Champion L77JC4 is a marine spark plug built as a quality OEM replacement for Evinrude outboard engines. It uses a copper core center electrode that increases conductivity and gives precise control of heat range, helping the plug resist fouling and overheating under sustained heavy engine loads that marine outboards regularly see on the water.

Beyond the copper core electrode, the L77JC4 is engineered for superior corrosion resistance, which matters in the salt and fresh water environments outboard engines operate in. Champion identifies this plug internally as Spark Plug #821, and it carries a 14mm thread size with a metal top material for a secure, standard fit in compatible cylinder heads. Each unit is sold as a single spark plug, making it easy to order the exact quantity needed for a full engine service or a single-cylinder replacement.

This spark plug is intended for Evinrude outboard engines and is delivered ready to install with no additional assembly required. Buyers replacing worn, fouled, or corroded plugs on their outboard can use the L77JC4 as a direct, dependable replacement that matches Champion's proven performance and durability standards.

Specifications

• Brand: Champion
• Manufacturer Part Number: L77JC4
• Champion Spark Plug Number: 821
• UPC: 037551000678
• Core Material: Copper
• Top Material Type: Metal
• Thread Size: 14mm
• Unit Count: 1 spark plug
• Weight: 0.15 pounds

Fitment

• Evinrude outboard engines

Frequently Asked Questions

What engines does the Champion L77JC4 spark plug fit? The Champion L77JC4 (Champion Spark Plug #821) is designed for Evinrude outboard engines.

Is the L77JC4 the same as Champion spark plug 821? Yes, L77JC4 is the public part number for the Champion Spark Plug #821 -- it is the same spark plug listed under Champion's internal number 821.

What is the thread size on this spark plug? The Champion L77JC4 has a 14mm thread size.

What material is the electrode made of? The center electrode on the Champion L77JC4 uses a copper core, which improves conductivity and gives more precise control of heat range for better overall wear.

How much does the Champion L77JC4 spark plug weigh? This spark plug weighs 0.15 pounds.

How many spark plugs come in one order? Each order of the Champion L77JC4 includes one spark plug.

Is this a genuine Champion spark plug or an aftermarket copy? The L77JC4 is a genuine Champion marine spark plug, manufactured by Champion under their own Spark Plug #821 designation, not a third-party aftermarket copy.

Does the L77JC4 resist fouling and corrosion? Yes, the Champion L77JC4 is built with superior corrosion resistance and is designed to resist fouling, which is important for marine outboard engines exposed to water and heavy loads.

What is the top material of the L77JC4 spark plug? The top material of the Champion L77JC4 is metal.

Can the L77JC4 handle heavy engine loads? The Champion L77JC4 is specifically designed to resist overheating under heavy engine loads, making it suitable for sustained outboard use.

Do I need any tools or additional parts to install the L77JC4? The Champion L77JC4 is a direct-fit spark plug for Evinrude outboard engines and requires only a standard spark plug socket for installation; no additional parts are included or needed.