MERCURY 266133 Driver Left Cylinder Head 5.0L

( Manufacturer Part Number: 266133 ), ( Part Type: Driver Cylinder Head ), ( Id: 70d66a67-c79e-46a7-8907-94819a278269 ), ( Interchange: 306-1197 )

Review MERCURY Driver Left Cylinder Head Assembly Oem 5.0l fits MARQUIS GRAND 1979–1985

The **Mercury Marquis 1979 1985 5.0L V8 Driver s Side Cylinder Head (Part # 266133)** is a meticulously crafted, high-performance component designed to restore or enhance the legendary power and reliability of Ford s iconic Windsor-based V8 engine. This left-side cylinder head, manufactured to exacting specifications, is a direct replacement for the original cast-iron assembly found in the 302 cubic-inch (5.0L) engines that powered the Marquis, Grand Marquis, and other full-size Ford vehicles during this era. Engineered with precision, it features the classic Ford design elements including the iconic "Ford" logo stamped into the valve cover, the robust rocker arm studs, and the robust valve spring retainers that were hallmarks of the time. The head is built to accommodate the standard 1.60-inch intake and 1.48-inch exhaust valves, ensuring proper airflow and combustion efficiency, while the integrated spark plug bosses and valve guides maintain the engine s original performance characteristics. Whether used in a classic restoration, a high-mileage rebuild, or a modern hot rod project, this cylinder head delivers the durability and performance expected from a Ford Windsor engine, making it an essential part for enthusiasts seeking to revive or refine their vehicle s powerplant. Its compatibility with aftermarket upgrades such as performance cams, high-flow heads, or fuel injection systems further solidifies its role as a versatile and dependable choice for Ford V8 aficionados.

### **Pros and Cons of Buying a Mercury 266133 (1979 1985 Marquis) Left Cylinder Head for a 5.0L Engine**

1. **Common and Well-Documented** The 5.0L Windsor engine (used in the Marquis) is one of the most popular Ford big-blocks, meaning parts, manuals, and repair guides are widely available. This makes troubleshooting and maintenance easier compared to rarer engines.

2. **Proven Reliability (When Maintained)** With proper upkeep regular oil changes, valve adjustments, and head gasket replacements the 5.0L can last well over 200,000 miles. Many examples from this era still run strong today, especially in classic muscle cars and trucks.

3. **Aftermarket Support** There is a vast aftermarket for performance upgrades, including high-flow heads, camshafts, intake manifolds, and fuel systems. This allows for significant power gains if you plan to modify the engine.

4. **Classic Muscle Car Appeal** The Marquis (and its Ford-based siblings like the Thunderbird and Grand Marquis) is a sought-after classic, especially in showroom condition. If you re restoring or preserving a vehicle from this era, the engine is a key component.

5. **Easier to Find Than Some Alternatives** While not as common as a small-block Chevy, the 5.0L Windsor is still more accessible than rare heads from other brands (e.g., Chrysler Hemi or early GM big-blocks).

6. **Potential for Restoration Value** If the cylinder head is in good condition, it could be worth more in the long run if the vehicle is restored to concours or high-running condition.

7. **Modularity with Other Ford Engines** Many parts (like the block, crankshaft, and pistons) are interchangeable with other Ford 5.0L engines, making swaps or repairs more flexible.

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- **Warped or cracked heads** (common due to poor cooling or overheating in older examples).

- **Worn valve seats or guides** (leading to oil leaks or poor sealing).

- **Threaded holes stripped or corroded** (especially on intake ports or spark plug threads).

- **Head gasket failure history** (though this is more block-related, heads can suffer from related issues).

- **Internal cracks** (especially around the valve springs or exhaust ports).

- **Pitting or corrosion** in the combustion chambers (common in high-mileage examples).

- **Worn rocker arms or pushrods** (if the engine was neglected).

3. **Fuel and Emissions Challenges** Older 5.0L engines were not built with modern emissions standards in mind. If you plan to run the car legally today, you may need:

- **EFI conversion** (replacing the carburetor with electronic fuel injection).

- **Exhaust modifications** (to meet smog laws).

- **OBD-II compliance** (if applicable).

- **Machining** (if warped or pitted).

- **Replacement parts** (valves, springs, seals, gaskets).

- **Labor costs** (if you re not doing the work yourself).

5. **Market Value Fluctuations** While the 5.0L is common, the specific year (1979 1985) may have variations in quality. Some years (e.g., early 1979 models) had weaker casting quality, while later models (mid-1980s) improved slightly.

6. **Risk of Overpaying** Without a clean bill of health, you might pay too much for a head that needs extensive work. Always get a **pressure test** (for warpage) and a **visual inspection** (for cracks, corrosion, or wear).

7. **Limited Stock Availability** While not rare, finding a **clean, non-warped head** in good condition can be competitive, especially if you re looking for a specific year or condition.

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### **Recommendation**

Buying a **1979 1985 Mercury Marquis 5.0L left cylinder head** can be a great investment if you re restoring a classic Ford vehicle, plan to modify the engine for performance, or have mechanical experience to assess and repair it. However, the head may require significant work to be fully reliable, and hidden issues (like warpage or cracks) can turn a seemingly good deal into a costly project.

- **Pressure test the head** (should be flat no more than 0.002" warpage).

- **Check for cracks** (use dye penetrant or a magnifying glass).

- **Test valve seats and guides** (no excessive wear or oil leakage).

- **Verify thread condition** (especially spark plug threads and intake ports).

- If the head is **warped or cracked**, it may need machining or replacement, which could cost **$300 $800 ** depending on labor.

- If it s **clean and sound**, it could be worth **$200 $500** depending on demand.

- Compare prices on forums like **Ford Truck Enthusiasts, Classic Ford, or eBay** to ensure you re not overpaying.

- If you re restoring a **show car**, prioritize **cosmetic and mechanical perfection** a rebuilt head is worth the investment.

- If you re building a **street/performance engine**, focus on **performance upgrades** (e.g., high-flow heads, cams) rather than just a stock replacement.

- If you re **not mechanically inclined**, budget for professional work this could add **$500 $1,500 ** to the total cost.

- **Buying a used rebuilt head** (check eBay, junkyards, or restoration shops).

- **Swapping in a head from a donor engine** (many 5.0Ls are pulled from wrecks).

- **Using a performance aftermarket head** (e.g., **JE, Edelbrock, or Holley** for better airflow).

- **Worth it if:** You have mechanical skills, the head is in good shape, and you re restoring a classic vehicle.

- **Not worth it if:** You re buying blind, the head is warped/cracked, or you lack the time/money for repairs.

- **Best approach:** **Buy from a trusted seller** (preferably with a **bill of health**) or **inspect it yourself** before purchasing.

**Bottom Line:** The 5.0L Windsor is a great engine, but cylinder heads from this era often require work. If you re prepared for potential repairs, it can be a solid addition to your project. If not, consider alternatives or a more inspected unit. Always prioritize **condition over price** in classic engine parts.

Details:

FORD VAN E100 79 8-302. Search for more parts GRAND MARQUIS. Cylinder Head. THUNDERBIRD 83-85 8-302 5.0L.

VERSAILLES 78 8-302, rocker arm bolts. VERSAILLES 79-80 8-302.

part #: 266133 price

• $600.00

specifications cylinderheapar:

• for models: Marquis, Grand
• for makes: Mercury
• for years: 1979-1985
• mpn: 266133
• part type: Driver Cylinder Head
• id: 70d66a67-c79e-46a7-8907-94819a278269
• interchange: 306-1197

shipping cylinderheapar:

• class: Standard
• service: Standard
• type: Fixed
• transit: 2-6 Days
• cost: $0.00

payments cylinderheapar:

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

general cylinderheapar:

• Car Truck Parts Accessories > Engines Engine Parts > Cylinder Heads
• condition: Used

returns cylinderheapar:

• policy: Returns Accepted
• paid by: Seller
• time: 30 Days

seller cylinderheapar:

• # reviews: 16315
• city: Brush, Colorado
• rating: 99.6%

offer cylinderheapar:

• started: May 5, 2026
• sold: 0
• availability: In Stock
• quantity: 1
• options: Ship-to-home

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