Sierra V8 Marine Spark Plug Wire Set - 18-8820-1
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The Sierra 18-8820-1 is a premium marine 8-cylinder spark plug wire set for select V8 sterndrive and inboard engines using compatible electronic ignition systems. This suppression-style wire set is built for marine engine compartments where heat, vibration, moisture, and ignition noise control are important. It is commonly used as an aftermarket replacement wire kit for select Delco EST, EFI, OMC Cobra, PCM, Crusader, MerCruiser, and Volvo Penta V8 applications where the engine's ignition layout and wire lengths match the kit.
Key Features
- Sierra premium marine spark plug wire set.
- Sierra part number: 18-8820-1.
- 8-cylinder / V8 wire set.
- Includes 9 leads total: 8 spark plug wires plus 1 coil wire.
- Designed for compatible marine electronic ignition applications.
- Suppression-style construction helps reduce ignition-related RFI/EMI noise around onboard electronics.
- High-temperature silicone-style jacketing and boots for marine engine compartment service.
- Corrosion-resistant terminal design for marine ignition environments.
- Intended for select V8 sterndrive and inboard engines where this wire set is specified by application chart.
Kit Contents & Wire Lengths
This set includes the following wire lengths:
- 2 wires — 27 in.
- 1 wire — 32 in.
- 2 wires — 38 in.
- 3 wires — 42 in.
- 1 coil wire — 14 in.
Confirm the wire lengths and terminal ends against the original set before installation.
Engine Compatibility
Common application context includes select V8 marine engines using compatible distributor-style electronic ignition systems, including:
- Select OMC Cobra V8 applications where specified
- Select 5.0L and 5.7L GM-based V8 sterndrive and inboard applications where specified
- Select 5.0L and 5.8L Ford-based V8 marine applications where specified
- Select MerCruiser V8 applications with compatible Delco EST or EFI ignition layouts where specified
- Select Volvo Penta V8 applications with compatible distributor ignition layouts where specified
- Select PCM / Pleasurecraft Marine and Crusader V8 applications where the wire routing and terminal style match
Use this wire set only where the Sierra application chart, engine model, distributor type, and existing wire layout confirm 18-8820-1 as the correct replacement.
Fitment Notice
Confirm fitment by engine manufacturer, model year, engine displacement, distributor type, ignition system, coil location, terminal style, and wire routing before ordering. V8 marine engines can use similar-looking wire sets with different terminal ends, coil-wire lengths, distributor cap styles, plug boot angles, and routing requirements. Matching only by engine displacement is not enough.
When This Part Needs Replacement
Replace spark plug wires if the engine has hard starting, rough idle, misfire under load, weak acceleration, visible arcing, cracked boots, burned insulation, corrosion at the terminals, loose plug connections, or high resistance in one or more leads. Wires should also be inspected during cap, rotor, spark plug, and seasonal ignition service, especially on engines exposed to salt air, bilge moisture, and exhaust manifold heat.
Installation Notes
Replace one wire at a time to preserve the correct firing order. Match each new wire to the closest original length and route it through the factory wire separators or loom supports. Keep wires away from exhaust manifolds, sharp brackets, belts, pulleys, and hot engine surfaces. Push each boot fully onto the spark plug, distributor cap, and coil terminal until it seats securely. Use dielectric grease only where appropriate inside the boot area, not on the metal terminal contact surface.
Alternate/Cross-Reference Part Numbers
- Sierra 18-8820-1 — premium marine spark plug wire set
- OMC / Cobra 503754 — cross-reference; verify by engine and ignition layout
- Mallory 9-28029 — cross-reference; verify by application
Parts Desk Insight
Marine spark plug wire sets should be matched by ignition system and routing, not just by cylinder count. The correct wire set needs the right plug boots, distributor terminals, coil wire, suppression design, and lead lengths. Poorly routed or incorrect wires can cause misfire, radio interference, premature insulation failure, and repeat ignition troubleshooting.
Shipping: Ships same or next day for fast Canada wide shipping. ⚓
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.
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