Champion QL77JC4 Marine Spark Plug | #828M | 4-Pack | Mercury 4-Stroke Outboard
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
The Standard Spark Plug for Mercury 4-Stroke Outboards — 4-Pack.
The Champion QL77JC4 is one of the most widely specified marine spark plugs for Mercury 4-stroke outboard engines. Part number 828M, the JC4 design features four ground electrodes arranged around a fine-wire centre electrode — delivering more consistent spark initiation, improved ignitability, and longer service life compared to a standard single-ground plug.
The QL-series long-reach thread and projected tip are engineered for the combustion chamber geometry of Mercury 4-stroke outboards. Sold in a 4-pack (Champion part 12198) — enough for most 4-cylinder outboard applications. Always verify fitment against your engine's owner's manual before ordering.
Key Features
- Champion QL77JC4 marine spark plug — 4-pack (Champion #828M)
- Four ground electrodes for consistent spark initiation and improved ignitability
- Fine-wire centre electrode for reduced voltage requirement and longer service life
- Long-reach QL-series thread with projected tip — engineered for Mercury 4-stroke outboard combustion chambers
- Resistor construction suppresses radio frequency interference (RFI)
Compatible Applications
- Mercury 4-stroke outboard engines specifying Champion QL77JC4 or equivalent
- Applications cross-referencing Mercury OEM spark plug part 896329828
- Mercury 4-stroke outboards where the owner's manual specifies a QL77JC4 or equivalent plug
- Verify fitment using your engine's owner's manual or the Champion spark plug application guide
Parts Desk Insights
The QL77JC4 is the plug to reach for on most Mercury 4-stroke outboard tune-ups — it's the OEM-specified plug for a wide range of Mercury 4-stroke models and is one of the most commonly replaced marine spark plugs we carry. Mercury recommends replacing spark plugs every 100 hours or annually, whichever comes first. If you're doing a full tune-up, pair the plug replacement with a fuel filter and gear oil service for best results.
Also available in a shop pack of 24 — see the Champion #828S Shop Pack if you're servicing a fleet or stocking up for the season. For the NGK equivalent commonly used in Mercury 4-stroke outboards, see the Quicksilver NGK Iridium Spark Plug Set. For other Champion QL-series marine plugs, see the Champion QL16V #876M or Champion QL78YC #938M.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.