MOONEY A-1390 Alternate Valve M20K

( Brand: Mooney ), ( Manufacturer Part Number: A-1390 ), ( Part Type: Valve ), ( Compatible Model: M20k ), ( Country Of Origin: United States )

Review MOONEY Alternate Static Source Valve Assembly

The **Mooney A-1390 M20K Alternate Valve** is a meticulously crafted, high-performance aircraft engine that embodies the legacy of Mooney s commitment to reliability, efficiency, and cutting-edge aeronautical engineering. Designed as a refined evolution of the classic M20K series, this engine features a **200 horsepower, air-cooled, horizontally opposed six-cylinder** configuration, delivering a potent yet smooth power output ideal for general aviation applications. The **alternate valve mechanism** represents a significant upgrade, offering enhanced durability and improved airflow efficiency, which translates to better throttle response, reduced carbon buildup, and extended component life. Built with precision-cast aluminum alloy cylinders and a robust crankshaft supported by seven main bearings, the M20K ensures exceptional strength and longevity, even under demanding flight conditions. Its **dry-sump lubrication system** guarantees consistent oil flow and protection against overheating, while the **fuel-injected carburetion** (optional on select models) eliminates vapor lock and provides precise fuel delivery for optimal performance across varying altitudes and temperatures. The engine s **direct-drive propeller system** simplifies installation and maintenance, making it a favorite among pilots who value both performance and ease of upkeep. Whether powering a Mooney M20 or other compatible aircraft, the A-1390 M20K Alternate Valve stands as a testament to Mooney s engineering prowess, blending heritage with modern advancements to deliver a dependable, high-revving powerplant that excels in both sport flying and cross-country adventures.

### **Pros and Cons of Buying a Mooney A1390 M20K (Alternate Valve)**

#### **Pros**

1. **Reliability and Track Record** The Mooney A-series, particularly the M20K variant, is known for its robust and dependable Lycoming O-360 engine, which has a long history of reliability in general aviation. The alternate valve design (a modified intake/exhaust system) improves airflow and reduces carbon buildup, extending valve life and reducing maintenance costs over time.

2. **Fuel Efficiency** The A1390 is one of the most fuel-efficient high-performance singles available, with a typical cruise burn rate of around **8 10 gallons per hour** at 12,000 feet. This makes it cost-effective for cross-country flights compared to larger or more powerful aircraft.

3. **Performance Capabilities** The M20K variant retains the original A1390 s strong performance, with a **160 170 mph** cruise speed and a **13,500-foot service ceiling**. The alternate valve design helps maintain these numbers with less engine wear over time.

4. **Low Operating Costs** Mooneys are generally cheaper to operate than many other high-performance singles (e.g., Cirrus, Piper Malibu). Maintenance is straightforward, and parts are widely available. The A1390 s simplicity reduces labor costs compared to more complex aircraft.

5. **Comfortable Cockpit and Flight Experience** The Mooney s ergonomic cockpit design, excellent visibility, and smooth ride make it a pleasant aircraft to fly, even for long cross-country trips. The T-tail design also provides good short-field performance.

6. **Strong Resale Value** Mooneys, especially well-maintained examples like the A1390, hold their value well. A properly cared-for M20K can retain a significant portion of its original purchase price over time.

7. **Community and Support** The Mooney owner community is active, with many clubs (e.g., Mooney Owners and Pilots Association) that provide networking, maintenance tips, and shared resources. This can be invaluable for troubleshooting and finding parts.

8. **Alternate Valve Advantages** The alternate valve modification (often retrofitted) reduces carbon fouling, extends valve life, and can improve throttle response. This is particularly beneficial for pilots who fly frequently or at high power settings.

9. **Simplicity and Durability** The Mooney s straightforward design means fewer systems to fail. The aircraft is built to last, with many examples exceeding **50,000 hours** with proper maintenance.

10. **Good for Pilots Transitioning from Lower-Performance Aircraft** The A1390 s performance is impressive enough for serious pilots but not overwhelming for those coming from smaller singles like the Cessna 172 or Piper Cherokee.

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#### **Cons**

1. **Higher Purchase Price** A well-maintained A1390 M20K with the alternate valve modification can cost **$250,000 $400,000 **, depending on age, hours, and condition. This is on the higher end for a high-wing single-engine aircraft.

2. **Maintenance Costs Can Add Up** While generally low, the Lycoming O-360 engine requires regular attention (magneto checks, oil analysis, valve adjustments). The alternate valve system, while beneficial, may introduce slightly more complexity in maintenance procedures.

3. **Limited Cargo Space** The Mooney s narrow fuselage and rear-mounted baggage compartment (accessed via the cockpit) result in less usable space for passengers or cargo compared to aircraft like the Piper Saratoga or Cessna 210.

4. **Less Comfort for Long Flights** While the ride is smooth, the Mooney s interior is compact, and long cross-country flights may feel cramped compared to larger aircraft. The lack of a toilet is also a drawback for extended trips.

5. **Fuel Capacity Limitations** The A1390 has a **50-gallon fuel capacity**, which limits range to approximately **1,000 1,200 nautical miles** with reserves. This requires careful planning for long trips, especially in crosswinds or adverse weather.

6. **Alternate Valve Modification Risks** While the alternate valve system is beneficial, improper installation or maintenance can lead to issues. Some pilots report slight increases in oil consumption or exhaust leaks if not properly tuned.

7. **Resale Market Competition** Mooneys are popular, but the market can be competitive. A buyer may need to negotiate hard for a specific model, especially if the aircraft has high time or lacks recent maintenance records.

8. **Limited Avionics Upgrade Path** While Mooneys can be retrofitted with modern glass cockpits (e.g., Garmin G3X), the installation is not as seamless as in newer aircraft. Some owners opt for analog panels, which may feel outdated compared to modern alternatives.

9. **Weather Sensitivity** The Mooney s performance is highly dependent on density altitude. In hot or high-altitude conditions, performance can degrade significantly, requiring careful pre-flight planning.

10. **Potential for Hidden Issues** As with any aircraft, a Mooney may have undocumented problems (e.g., corrosion, improper past maintenance). A thorough pre-purchase inspection (PPI) by an experienced mechanic is critical to avoid surprises.

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### **Ending Conclusion**

The **Mooney A1390 M20K with alternate valve** is an excellent choice for pilots who prioritize **reliability, fuel efficiency, and performance** without the complexity of more advanced aircraft. Its strong track record, low operating costs, and comfortable flight experience make it a favorite among general aviation enthusiasts. The alternate valve modification further enhances its longevity and efficiency, making it a smart investment for those who plan to fly it frequently.

However, the **higher purchase price, limited space, and maintenance considerations** mean it may not be the best fit for casual flyers or those seeking maximum comfort or cargo capacity. Buyers should ensure the aircraft has a **clean history, proper maintenance records, and a thorough inspection** before purchasing.

### **Recommendation**

- You are a serious pilot who values **performance, efficiency, and reliability**.

- You plan to fly **frequently and cross-country**, benefiting from its fuel savings and long-range capability.

- You prefer a **simple, durable aircraft** with a strong owner community.

- You are willing to invest in **proper maintenance and inspections** to maximize its lifespan.

- You prioritize **maximum comfort or cargo space** over performance.

- You are on a **tight budget**, as the upfront cost and potential maintenance expenses may be prohibitive.

- You prefer **modern glass cockpits and avionics upgrades**, as retrofitting can be costly.

- You do not have access to **proper pre-purchase inspection resources** to verify the aircraft s condition.

**Final Verdict:** For the right buyer an experienced pilot who appreciates Mooney s strengths the A1390 M20K is a **superior choice** in the high-performance single-engine market. However, it requires careful consideration of your flying needs and financial commitment. Always conduct a **detailed PPI** and consult with a trusted aviation professional before making a purchase.

Details:

As removed working when. Condition: Used - Good Condition. A business or residential address is required for delivery. Alt part number: 820252-517.

Electronics may have anti-tamper seals that must remain intact. Aircraft model: M20K. Buyer pays return shipping. A-1390 Mooney M20K Alternate Static Source Valve Assembly: Photos Details about this part Assembly Part number.

Aircraft make: Mooney. Please see pics.

part #: a1390 prices

• $124.00-$170.00

specifications engineaviatio:

• brand: Mooney
• mpn: A-1390
• part type: Valve
• compatible model: M20k
• country of origin: United States

general engineaviatio:

• Aviation Parts Accessories > Engines > Engine Components
• condition: Used

seller engineaviatio:

• # reviews: 1528
• city: Gainesville, Florida
• rating: 100.0%

shipping engineaviatio:

• class: Standard, Expedited, One-day
• cost: $12.71
• transit: 3-7 Days
• service: UPS Ground, UPS 3 Day Select, UPS 2nd Day Air, UPS Next Day Air
• type: Calculated
• carrier: UPS

payments engineaviatio:

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

returns engineaviatio:

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

offer engineaviatio:

• best offers: True
• quantity: 1
• availability: In Stock
• started: June 8, 2026
• options: Ship-to-home
• sold: 0

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