MERCURY 18787-3 Blackmax Cylinder Head Set 2-STROKE V6 135-200HP 18787-C

( Manufacturer Part Number: 18787-3 ), ( Part Type: Cylinder Head ), ( Country Of Origin: United States )

Review MERCURY Blackmax 2-stroke V6 135-200hp Cylinder Head Set 18787 fits MARINER

The **Mercury 18787-3 Mariner BlackMAX 2-Stroke V6 Cylinder Head Set (18787, 18787-C)** is a high-performance, precision-engineered component designed exclusively for Mercury s legendary 135 200 horsepower 2-stroke V6 outboard motors, including the iconic Mariner BlackMAX series. This meticulously crafted cylinder head set is engineered to deliver unmatched reliability, efficiency, and power output, making it an essential upgrade for boaters seeking optimal performance in both freshwater and saltwater environments. Constructed from high-grade, corrosion-resistant materials, the head set features a robust, lightweight design that ensures durability while maintaining structural integrity under demanding operating conditions. The precision-machined components, including the intake and exhaust ports, are optimized for superior airflow, reducing friction and maximizing combustion efficiency critical factors for achieving peak horsepower and torque across the 135 200 hp range. Whether deployed in high-speed cruising, heavy-duty towing, or extended offshore excursions, this cylinder head set enhances throttle response, fuel economy, and overall engine longevity by minimizing wear and tear on internal components. Backed by Mercury s reputation for innovation and marine-grade engineering, this part is a direct replacement for the original equipment, ensuring seamless compatibility with the 18787 and 18787-C models while adhering to strict manufacturing standards. Ideal for performance enthusiasts, professional anglers, or fleet operators, the Mariner BlackMAX cylinder head set exemplifies Mercury s commitment to delivering power, precision, and dependability proving that even in the most demanding marine applications, this component stands as a testament to engineering excellence.

### **Pros and Cons of buying a Mercury 18787-3 (Mariner BlackMAX 2-Stroke V6 Cylinder Head Set)**

1. **Performance Enhancement** This cylinder head set is designed to improve airflow and combustion efficiency in Mercury s 2-stroke V6 engines (135-200 HP range), which can lead to better throttle response, increased horsepower, and smoother operation.

2. **Compatibility with High-Performance Mods** The BlackMAX series is engineered to work with other performance upgrades, such as high-flow exhausts, tuned carburetors, or electronic fuel injection (EFI) conversions, allowing for further tuning potential.

3. **Durability and Quality** Mercury s aftermarket parts, especially those in the BlackMAX line, are built to withstand the demands of marine applications, including saltwater corrosion resistance and reinforced construction.

4. **Easier Maintenance** Some cylinder head sets come with improved gasket materials and sealing solutions, reducing the risk of leaks and simplifying installation compared to stock heads.

5. **Cost-Effective Upgrade** Compared to a full engine rebuild or replacement, this part is relatively affordable, offering a significant performance boost without a major investment.

6. **Warranty Support** Mercury Marine typically provides warranties on aftermarket parts, offering some peace of mind against manufacturing defects.

7. **Improved Reliability** Properly installed cylinder heads can reduce internal wear, extend engine life, and minimize the risk of catastrophic failure (e.g., blown head gaskets or valve issues).

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1. **Installation Complexity** Replacing cylinder heads requires mechanical expertise, proper tools, and disassembly of the engine. If not done correctly, it can lead to misalignment, leaks, or even engine damage.

2. **Compatibility Issues** While designed for Mercury s 135-200 HP 2-stroke V6 engines, there may be slight variations between models (e.g., 1990s vs. early 2000s engines). Ensuring the exact fitment is crucial some owners report minor clearance or bolt pattern mismatches.

3. **Cost of Additional Mods** To fully realize performance gains, you may need to pair this with other upgrades (e.g., new pistons, rings, or a tuned carburetor), which can add to the total cost.

4. **Saltwater Corrosion Risk** Even with corrosion-resistant materials, prolonged exposure to saltwater can still degrade components over time, requiring more frequent inspections and maintenance.

5. **Limited Longevity Compared to 4-Stroke** Mercury s 2-stroke engines are inherently less durable than modern 4-stroke outboards. While this head set improves reliability, the engine itself may still require more frequent overhauls.

6. **Learning Curve for Tuning** If you re not experienced with marine engine tuning, improper adjustments (e.g., too rich fuel mixture) can lead to excessive carbon buildup, reduced efficiency, or even engine damage.

7. **Resale Value Impact** High-performance aftermarket parts can make a boat less appealing to buyers who prefer stock or lightly modified engines, potentially reducing resale value.

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### **Conclusion**

The **Mercury 18787-3 BlackMAX cylinder head set** is a solid upgrade for owners of 135-200 HP 2-stroke V6 engines looking to boost performance, reliability, and longevity. It is particularly beneficial for those who plan to run their engines at higher RPMs or pair it with other modifications. However, the installation demands skill, and additional tuning may be necessary to maximize benefits.

If you re mechanically inclined, willing to invest in complementary upgrades, and prioritize performance over stock simplicity, this part is a worthwhile consideration. For casual boaters or those without mechanical experience, the complexity of installation and potential tuning challenges may outweigh the benefits.

### **Recommendation**

- **Buy if:** You have a 135-200 HP Mercury 2-stroke V6, plan to run it aggressively, and are prepared for installation or have a trusted mechanic perform it. Consider pairing it with a high-flow exhaust and tuned carburetor for best results.

- **Avoid if:** You lack mechanical experience, want a hassle-free upgrade, or are unsure about long-term maintenance. In such cases, a full engine rebuild or a modern 4-stroke outboard may be more practical.

- **Alternative Consideration:** If your engine is older and showing signs of wear, evaluate whether a **full engine overhaul** or a **replacement with a newer 4-stroke model** (e.g., Mercury Verado) would be more cost-effective in the long run.

For the best outcome, consult a Mercury Marine specialist or a marine engine technician before purchasing to confirm compatibility and discuss installation requirements.

Details:

Pair of cylinder heads from a 1990 Mercury Mariner 135hp V6. Light damage on top cylinders 1 and 2 but can be easily cleaned up or machined.

part #: 187873 prices

• $89.00-$120.00

specifications ouboaen:

• for models: Mariner
• for makes: Mercury
• mpn: 18787-3
• part type: Cylinder Head
• country of origin: United States

returns ouboaen:

• policy: No Returns

seller ouboaen:

• city: Green Bay, Wisconsin
• # reviews: 232
• rating: 100.0%

general ouboaen:

• condition: Used
• Boat Parts > Outboard Engines Components > Intake Fuel Systems

shipping ouboaen:

• carrier: USPS
• class: Standard
• type: Calculated
• transit: 4-9 Days
• cost: $10.21
• service: USPS Ground Advantage

payments ouboaen:

• credit card: Visa
• wallet: Apple-pay
• other

offer ouboaen:

• options: Ship-to-home
• started: March 14, 2026
• availability: In Stock
• quantity: 1
• sold: 0

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