1. Propellers Boat Parts For Sale
  2. sku: 12121913303695793
  3. MERCRUISER 49978

MERCRUISER 49978 Prop Spline Rh Cone 15.75X19P

fits model: A1. year: 1968–2017.

15.75x19p Mercruiser 49978 Vintage 1968 Ii Prop 17 Spline A1 Rh Aluminum With Cone

( Brand: Mercruiser ), ( Manufacturer Part Number: 49978 ), ( Part Type: Aluminum Prop )

Review MERCRUISER Vintage Prop Spline Rh Aluminum Cone fits A1 1968–2017

The **Mercruiser 49978 1968 Propeller (15.75" x 19" Pitch, 17-Spline A1 RH Cone)** is a meticulously crafted, high-performance marine propeller designed exclusively for classic and vintage Mercruiser outboard and sterndrive applications from the late 1960s, including the iconic 1968 models. Engineered with precision and built to endure the demands of both recreational cruising and spirited boating, this propeller features a **15.75-inch diameter** and a **19-inch pitch**, striking an optimal balance between acceleration and top-end speed for mid-sized boats ranging from 20 to 25 feet in length. The **17-spline shaft connection** ensures a secure, vibration-dampening fit, reducing strain on the engine and transmission while maximizing power transfer, a critical consideration for older Mercruiser setups where wear and tear over time can compromise performance.

The **A1 right-hand (RH) cone** is a key component, designed to align seamlessly with the Mercruiser s original drive unit, providing a snug, interference-fit that minimizes slippage and backlash. This propeller is forged from high-grade **marine-grade aluminum bronze**, a material renowned for its exceptional corrosion resistance, durability, and ability to withstand the harsh conditions of saltwater and frequent exposure to the elements. The blade design incorporates a **symmetric, hydrodynamic profile** with carefully contoured surfaces to optimize water flow, reducing cavitation and improving efficiency across a wide RPM range. Whether accelerating quickly from a stop or maintaining steady cruising speeds, this propeller delivers smooth, responsive performance with minimal noise and vibration, a hallmark of Mercruiser s engineering legacy.

For collectors, restorers, and enthusiasts seeking to revive the original performance of their 1968 Mercruiser-equipped vessels, this propeller is an ideal replacement or upgrade. Its **OEM specifications** ensure compatibility with stock Mercruiser outboards and sterndrives, while its robust construction and timeless design make it a reliable choice for both daily use and special occasions. Whether paired with a restored classic or a modernized classic boat, the **Mercruiser 49978 propeller** stands as a testament to the brand s commitment to quality and performance, offering a perfect blend of heritage and modern engineering for those who appreciate the art of boating.

### **Pros and Cons of Buying a 1968 Mercruiser 49978 15.75" x 19" Prop (17 Spline, A1 RH Cone)**

#### **Pros:**

1. **Classic and Reliable Engine** The 49978 is a well-known, robust Mercruiser inline-six engine known for durability, especially in older models. With proper maintenance, it can last decades.

2. **Strong Torque** The 17-spline shaft and large propeller (15.75" x 19") suggest a high-torque application, ideal for heavy-duty tasks like towing, deep-sea fishing, or large boat operation.

3. **Proven Performance** The A1 cone and right-hand drive are standard for older Mercruisers, meaning parts and rebuild kits are widely available.

4. **Potential for Restoration** If the engine is in rough shape, a rebuild or restoration can be cost-effective compared to modern outboards, especially if you have mechanical skills.

5. **Vintage Appeal** For collectors or enthusiasts, a well-preserved 1968 Mercruiser can be a prized addition to a fleet, especially if it s part of a classic boat.

6. **Lower Initial Cost** Compared to modern outboards or even newer inboards, a used 1968 Mercruiser engine can be acquired at a fraction of the price, making it a budget-friendly option for budget-conscious buyers.

7. **Compatibility with Older Boats** If you re restoring or maintaining a vintage boat, this engine will fit seamlessly without needing extensive modifications.

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#### **Cons:**

1. **Age and Wear** At 56 years old, the engine likely has significant mileage and wear. Internal components like bearings, seals, and pistons may be degraded, requiring a full rebuild or replacement.

2. **Maintenance Requirements** Older Mercruisers demand meticulous upkeep, including regular oil changes, valve adjustments, and potential rod bearing replacements. Neglect can lead to catastrophic failure.

3. **Parts Availability** While basic parts are still available, some specialized components (e.g., exact seals, gaskets, or rare bearings) may be harder to source, increasing repair costs.

4. **Fuel and Emissions Standards** Modern fuel contains additives that can degrade older engines faster. Running it on modern fuel may require additional maintenance (e.g., fuel system cleaning).

5. **Reliability Concerns** Without a recent service history, there s a risk of hidden issues like cracked blocks, worn crankshafts, or failed water pumps. A professional inspection is critical.

6. **Resale Value** Even in good condition, a 1968 Mercruiser won t hold value like a modern engine. If you plan to sell later, depreciation will be significant.

7. **Noise and Vibration** Older inboard engines tend to be louder and vibrate more than modern counterparts, which can be an issue for quiet operation.

8. **Electrical System Limitations** The wiring and electrical components may not meet modern standards, requiring upgrades if you want to integrate modern electronics or safety features.

9. **Environmental Regulations** Some areas have restrictions on older engines due to emissions. You may need to modify or replace the engine to comply with local laws.

10. **Skill Dependency** Operating and maintaining this engine effectively requires mechanical knowledge. Without experience, repairs can be costly or risky.

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### **Conclusion and Recommendation**

Buying a **1968 Mercruiser 49978 with a 15.75" x 19" prop** is a **high-risk, high-reward** decision. It s best suited for:

- **Enthusiasts or collectors** who appreciate vintage engines and are willing to invest time and money into restoration.

- **Budget-conscious buyers** who can afford a full rebuild or replacement of worn components.

- **Boat owners** with mechanical skills or access to a trusted mechanic to handle maintenance.

**If you re not prepared for the challenges of an older engine**, consider alternatives:

- A **rebuilt or remanufactured** version of this engine (if available) to reduce risk.

- A **modern inboard or outboard** with better reliability, fuel efficiency, and emissions compliance.

- A **used but well-maintained** Mercruiser from a later model year (e.g., 1980s 1990s) that still offers good performance with fewer age-related issues.

**Final Recommendation:** Only purchase this engine if:

You have a **detailed service history** or can verify its condition through a **pre-purchase inspection**.

You re **prepared for a major rebuild** (or have the budget to replace critical components).

You **enjoy mechanical work** and can commit to ongoing maintenance.

You re buying it for **personal use or restoration**, not as an investment.

If any of these conditions aren t met, prioritize a **modern or thoroughly rebuilt engine** to avoid costly surprises.

Details:

Buyer Pays Return Shipping. Blades have some wear see pics. Vintage 1968 Mercruiser II Prop 15.75x19P 17 Spline 49978A1 RH Aluminum w/ Cone.

part #: 49978 price

  • $150.00

specifications propboapar:

  • for models: A1
  • for years: 1968-2017
  • brand: Mercruiser
  • mpn: 49978
  • part type: Aluminum Prop

returns propboapar:

  • paid by: Buyer
  • policy: Returns Accepted
  • time: 14 Days

shipping propboapar:

  • class: Standard
  • carrier: USPS
  • service: USPS Ground Advantage
  • cost: $15.62
  • transit: 10-14 Days
  • type: Calculated

seller propboapar:

  • # reviews: 526
  • city: Gravois Mills, Missouri
  • rating: 99.6%

offer propboapar:

  • sold: 0
  • best offers: True
  • started: February 11, 2026
  • options: Ship-to-home
  • quantity: 1
  • availability: In Stock

general propboapar:

  • Parts Accessories > Boat Parts > Propellers
  • condition: Used

payments propboapar:

  • wallet: Google-pay
  • other
  • credit card: Discover
for models: a1, for years: 1968-2017, part type: aluminum prop,
category: boat parts > propellers, sku: 12121913303695793,
Mercruiser 49978 Is Similar To:
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1 offer $150.00 USD
  • Used. Offer #1 priced at $150.00 + $16.87 shipping estimate = $166.87* total. +$16.87 shipping

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