Mercury – Quicksilver 816608Q61 Red Wire Spark Plug Wire Kit | GM V8 Marine Engines (454–502 CID) | Thunderbolt IV & V Ignition | 816608Q61

Overview

The right spark plug wires can bring an older engine back to life. The Quicksilver 816608Q61 Red Wire Spark Plug Wire Kit is designed for vintage V8 GM-based MerCruiser engines (454–502 CID) using Thunderbolt IV and V ignition systems (1981–1997). Built to Mercury’s standards, this OEM set keeps your ignition system firing clean and strong, restoring smooth starts and crisp throttle response.

Each wire is precision-cut to factory length, finished in a tough red jacket that resists heat and moisture. It’s a direct-fit upgrade that installs easily and looks great while keeping your engine running the way it should.

Key Features

• Purpose: Replaces old or damaged wires to restore clean, consistent spark delivery.
• Fitment: For V8 GM-based MerCruiser engines (454–502 CID) with Thunderbolt IV & V ignition systems (1981–1997).
• Kit Contents: Includes a full set of eight red spark plug wires with pre-installed boots for plug-end connections.
• Design: Each wire is custom-length for the correct plug location and clean routing.
• Marine Durability: Built for heat, vibration, and moisture resistance in harsh marine conditions.

Engine & Boat Compatibility

• GM-based V8 MerCruiser engines (454 CID, 502 CID)
• Thunderbolt IV and V ignition systems (1981–1997)
• Common on performance cruisers, large tow boats, and classic offshore rigs

Performance & Practical Benefits

The 816608Q61 wire kit keeps spark energy strong and even across all eight cylinders. With low-resistance cores and tight-fitting boots, these wires deliver full voltage for easy starts, smooth idle, and better fuel burn. You’ll feel the difference — quicker throttle response and a cleaner pull when you open it up.

The marine-grade insulation stands up to heat, vibration, and salt exposure without cracking or fading. The red jacket gives your engine bay a sharp, clean look while providing a durable layer of protection that lasts for years.

Why Buy OEM

Mercury’s OEM ignition components are purpose-built for marine use — not rebranded automotive parts. Every Quicksilver wire set is tested for correct resistance, length, and durability in the toughest environments. Aftermarket kits often fall short, with materials that degrade faster or mismatched wire lengths that throw off spark timing.

With a genuine Quicksilver wire kit, you get the right fit, the right resistance, and the same performance your engine had when it was new. It’s reliable, tested, and made for life on the water.

FAQ

Q1: Which engines use the Quicksilver 816608Q61 kit?
A: It fits V8 GM-based MerCruiser engines (454–502 CID) with Thunderbolt IV or V ignition systems (1981–1997).

Q2: How many wires are included?
A: The kit includes eight red wires, each pre-fitted with spark plug boots.

Q3: Can these be used in saltwater?
A: Yes. They’re made from marine-rated materials that resist corrosion, salt, and heat.

Q4: Are they easy to install?
A: Very. Replace one wire at a time to keep your firing order straight — no special tools needed.

Q5: Why choose OEM wires?
A: OEM wires fit perfectly, perform better, and last longer under marine stress. You’ll get factory-quality performance without guesswork.