816608A61 Aftermarket Mercruiser Thunderbolt V8 Ignition Lead Set 454 7.4L, 502 6.2L | Sawley's Select Marine Parts

🔧 Product Description

Aftermarket replacement Big-Block V8 Thunderbolt Ignition Lead Set - Replaces Part Number: 816608A61

New nine-lead ignition-cable set replacing MerCruiser 816608A61 for GM 454 CID/7.4L and 502 CID/8.2L big-block V8 engines with Thunderbolt ignition.

⚙️ Key Features

• Nine-lead V8 distributor ignition set

• Correct big-block lead lengths and routing

• Supports 7.4L/454 and 8.2L/502 engines

• Marine suppression cable and heat-resistant boots

• Includes eight plug leads and one coil lead

🧰 Kit / Assembly Contents

• 8 × Spark-plug leads - serviced only as kit P/N 816608A61

• 1 × Distributor-to-ignition-coil lead - serviced only as kit P/N 816608A61

🔄 Supersession & Cross Reference

OEM Supersession Chain:

• 816608Q61 → Supersedes/updates 816608A61

• 816608A61 → Cross-references 816761A2, 816761A15, 813720A2, 43376A14/A2/A1 and 42841A5

OEM / Related Numbers:

• 816608Q61

• 816761A2

• 816761A15

• 813720A2

• 43376A14

• 43376A2

• 43376A1

• 42841A5

Aftermarket / Verified Equivalents:

• Sierra: 18-8804

• Mallory: 9-28001

• Recmar big-block Thunderbolt lead-set family

🚤 Compatibility

Commonly used on:

• MerCruiser GM big-block V8 Thunderbolt ignition engines

Typically suits:

• Engine / Equipment models:

• 7.4L/454 V8

• 8.2L/502 V8

• 330HP, 365HP, 390HP and high-performance big-block packages using the listed wire set

• HP / Output Range: Approximately 330HP - 500HP

• Engine / System Type: GM big-block V8 petrol marine engine with distributor ignition

• Year Range: Principally 1980s through early-2000s; serial-dependent

• Serial / Component Identification: Confirm distributor ignition and big-block routing; 502 CID equals approximately 8.2L.

🔌 Function

The ignition leads carry high-voltage energy from the distributor or individual coils to the spark plugs. Marine-grade insulation and correctly fitted terminals prevent leakage, crossfire and radio-frequency interference.

Common signs of failure / service requirement:

• Misfire under acceleration or high load

• Visible arcing in darkness or around damp lead boots

• Cracked, hardened or oil-contaminated insulation

• Excessive lead resistance or open circuit

• Rough idle, crossfire or radio-frequency interference

📦 Condition

• New aftermarket replacement part

• Brand new

• Supplied in original or equivalent packaging