Mercury – Quicksilver 815407Q5 Distributor Cap Kit | V6 GM MerCruiser Engines | Thunderbolt IV & V HEI Ignition | 815407Q5

Overview

A strong, even spark is what brings your MerCruiser engine to life — and keeps it running smooth all day long. The Quicksilver 815407Q5 Distributor Cap Kit makes sure that spark stays clean, steady, and reliable. Designed for V6 GM-based MerCruiser engines with Thunderbolt IV or V HEI ignition systems, this OEM kit includes both the cap and rotor built to factory spec.

It’s made for the real world of boating — heat, vibration, and constant exposure to moisture. When you swap in a new cap and rotor, you’ll notice easier starts, a smoother idle, and that solid, confident throttle response that tells you your ignition is dialed in just right.

Key Features

• Purpose: Restores crisp spark timing and consistent ignition performance in V6 marine engines.
• Fitment: For GM-based MerCruiser V6 engines using Thunderbolt IV or V HEI ignition systems.
• Materials: Cap molded from a PBT/PET composite that resists warping and heat damage.
• Electrical Design: Solid brass terminals resist corrosion and pitting for a clean, stable spark path.
• Durability: High strength-to-weight ratio rotor resists cracking and holds timing under vibration.
• RFI Protection: Built to reduce radio frequency interference, keeping your electronics quiet and clear.

Engine & Boat Compatibility

• V6 GM MerCruiser sterndrive and inboard engines
• Thunderbolt IV and V HEI ignition systems
• Common on bowriders, cruisers, and mid-size performance boats

Performance & Practical Benefits

When the ignition cap and rotor start to wear, the engine’s spark weakens — leading to hesitation, hard starts, and rough idle. The 815407Q5 kit solves that by restoring tight, corrosion-free contact points and proper spark spacing. The brass inserts deliver an even spark to every cylinder, while the composite housing stays stable under heat and vibration.

You’ll notice smoother acceleration, quicker starting, and cleaner running right away. The RFI-resistant design also helps keep your electronics — from depth finders to radios — free from interference. It’s a simple part that brings your engine’s performance right back where it should be.

Why Buy OEM

Mercury’s OEM ignition parts are designed from the ground up for marine duty. They’re not repurposed automotive components — every detail, from the brass terminals to the resin mix, is chosen for long life in salt, heat, and humidity.

Aftermarket caps and rotors often look similar but tend to use softer metals or cheaper plastics that warp, crack, or corrode faster. With genuine Quicksilver parts, you get the exact fit, performance, and dependability your engine was built around — no surprises, just reliability.

FAQ

Q1: What engines fit the Quicksilver 815407Q5?
A: It’s made for V6 GM-based MerCruiser engines running Thunderbolt IV or V HEI ignition systems.

Q2: Does the kit include both the cap and rotor?
A: Yes, the 815407Q5 kit includes both parts.

Q3: Is it suitable for saltwater use?
A: Yes. The brass contacts and reinforced housing resist corrosion in both salt and freshwater.

Q4: How often should I replace the cap and rotor?
A: Check annually or every 100 hours — replace if there’s corrosion, cracks, or misfiring.

Q5: Can I replace it myself?
A: Definitely. It’s a straightforward job — just mark your wires, swap the parts, and torque to spec per your service manual.