Champion QL78YC Marine Spark Plug | #938M | 4-Pack | Long-Reach 4-Stroke Outboard
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Long-Reach Marine Spark Plug for 4-Stroke Outboards — 4-Pack.
The Champion QL78YC is a long-reach, projected-tip marine spark plug designed for 4-stroke outboard engines. Part number 938M, the YC-series features a standard ground electrode with a projected tip for improved ignitability and a built-in resistor to suppress radio frequency interference — making it well-suited for use near marine electronics and communication equipment.
The QL-series long-reach thread is engineered for outboard combustion chambers that require deeper plug engagement than standard-reach plugs. Sold in a 4-pack (Champion part 12217). Always verify fitment against your engine's owner's manual or Champion application guide before ordering.
Key Features
- Champion QL78YC marine spark plug — 4-pack (Champion #938M)
- Long-reach QL-series thread — for outboard engines requiring deeper plug engagement
- Projected tip for improved ignitability and combustion efficiency
- Standard ground electrode with resistor construction for RFI suppression
- Designed for 4-stroke marine outboard applications
Compatible Applications
- Evinrude and Johnson 4-stroke outboard engines specifying Champion QL78YC or equivalent
- Mercury and Mariner 4-stroke outboard engines specifying Champion QL78YC or equivalent
- Long-reach 4-stroke outboard applications cross-referencing Champion #938M or part 12217
- Verify fitment using your engine's owner's manual or the Champion spark plug application guide
Parts Desk Insights
The QL78YC is the standard single-ground-electrode alternative to the Champion QL77JC4 in the long-reach QL family. If your engine specifies the QL78YC, use the QL78YC — the YC and JC4 are not interchangeable despite sharing the same QL-series thread reach. The JC4's four-ground-electrode design offers improved spark consistency, but only use it if your engine's manual specifies it or an equivalent.
Also available in a shop pack of 24 — see the Champion #938S Shop Pack if you're servicing a fleet or stocking up for the season. For other Champion QL-series marine plugs, see the Champion QL16V #876M.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 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.