1. Engine Crankshafts Products
  2. sku: 19581340841972722
  3. MOLNAR 400-3750CB6F-585

MOLNAR TECHNOLOGIES 400-3750CB6F-585 Forged Crank Mains 3.750

fits model: 750, 400.

400-3750cb6f-585 Molnar Technologies Sbc Forged Crank 3.750 Stroke 400 Mains

( Brand: Molnar Technologies ), ( Manufacturer Part Number: 400-3750CB6F-585 ), ( Part Type: Crank ), ( Performance Part: Yes )

Review MOLNAR TECHNOLOGIES Sbc Forged Crank 3.750 Stroke Mains fits 750 400

The **Molnar 400-3750CB6F-585 Forged Crankshaft** is a precision-engineered component designed to deliver exceptional durability, performance, and reliability in high-stress applications, particularly within heavy-duty diesel engines. Crafted from **high-grade forged steel**, this crankshaft is built to withstand the immense torque and cyclic loading demands of modern marine, industrial, and off-road diesel engines, including those in the 400-series lineup. The **3.750-inch main journal diameter** ensures robust structural integrity, reducing the risk of fatigue failure and extending the crankshaft s operational lifespan under extreme conditions. Each journal and rod journal is meticulously **ground to tight tolerances**, often featuring a **nitrided or induction-hardened surface** to enhance wear resistance and minimize friction, which is critical for maintaining efficiency in high-load environments.

The **CB6F designation** indicates a specific design iteration optimized for compatibility with aftermarket and performance-focused engine builds, offering a balance between strength and weight savings compared to traditional castings. The **585 series** denotes a refined version with improved balancing and dynamic characteristics, reducing vibration and enhancing smoothness key factors for engines operating at high RPMs or under continuous heavy loads. Molnar s proprietary forging process ensures a **fine, uniform grain structure**, eliminating internal voids and stress concentrations that could lead to premature failure. This attention to metallurgical integrity, combined with **precision machining and heat treatment**, results in a crankshaft capable of handling the most demanding applications, from high-torque marine propulsion systems to rugged off-road and agricultural machinery.

Beyond its mechanical superiority, the Molnar 400-3750CB6F-585 crankshaft is engineered with **modern engine design considerations** in mind, including optimized counterweight placement to minimize torsional vibration and improve overall drivetrain efficiency. The **smooth, polished surfaces** of the journals and rod eyes not only reduce wear on bearings and bushings but also facilitate easier installation and maintenance. Whether integrated into a stock engine for enhanced longevity or a modified powerplant for increased performance, this crankshaft represents a premium investment for operators seeking uncompromising reliability and performance. Backed by Molnar s reputation for innovation and quality, it stands as a testament to the brand s commitment to delivering components that push the boundaries of what s possible in diesel engine design.

### **Pros and Cons of buying a Molnar 400-3750CB6F-585 Forged Crank (3.750" Mains, 400 Series)**

#### **Pros:**

1. **High-Quality Forged Construction** Molnar cranks are forged from premium steel, which provides superior strength, durability, and resistance to fatigue compared to cast or billet cranks. This makes them ideal for high-performance applications, including drag racing, street tuning, and heavy-duty use.

2. **Balanced and Precision-Machined** Molnar cranks undergo rigorous balancing and machining processes to ensure smooth operation, reducing vibration and improving engine longevity. This is particularly beneficial for forced-induction builds or high-RPM applications.

3. **Proven Performance in Extreme Conditions** The 400 series is designed for high-stress environments, such as big-block Chevy engines, where reliability under heavy loads is critical. The 3.750" main journals are robust enough to handle aggressive camshafts, high compression ratios, and forced induction without excessive wear.

4. **Compatibility with Aftermarket Parts** Molnar cranks are widely used in performance builds, meaning they integrate well with aftermarket rods, pistons, and other components. This makes them a versatile choice for custom engine projects.

5. **Warranty and Support** Molnar offers a solid warranty (typically 12 months or more) and has a reputation for customer service, which can be reassuring when investing in a high-end component.

6. **Reduced Risk of Catastrophic Failure** Forged cranks are less prone to cracking or breaking under extreme stress compared to cast cranks, making them a safer option for high-performance applications.

7. **Customization Options** Molnar provides various crankshaft configurations (e.g., different rod journal sizes, counterweight options) to tailor the crank to specific engine needs, such as low-end torque or high-RPM revving.

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#### **Cons:**

1. **High Cost** Forged cranks like the Molnar are significantly more expensive than cast or billet alternatives. The premium price reflects the superior materials and machining, but it may not be justified for mild street engines or budget builds.

2. **Weight Considerations** While forged cranks are durable, they are also heavier than some billet or lightweight cast options. This added weight can slightly reduce engine responsiveness, though the difference is often negligible in most applications.

3. **Installation Complexity** Replacing a crankshaft requires significant labor, including rod journal resizing, main bearing alignment, and balancing. This can be a time-consuming and costly process if not done properly.

4. **Limited Availability of Replacement Parts** While Molnar is a reputable brand, some smaller aftermarket suppliers may not carry their parts. This could pose challenges if maintenance or repairs are needed down the line.

5. **Overkill for Mild Applications** If you re running a stock or mildly modified engine with no forced induction or aggressive camshafts, a forged crank may offer unnecessary redundancy. In such cases, a high-quality cast crank could suffice at a fraction of the cost.

6. **Potential for Overbuilding** Some builders may end up with a crank that s stronger than needed for their specific power goals, leading to wasted investment. It s essential to match the crank to the engine s actual demands.

7. **Compatibility with Stock Engines** If you re working with a stock engine block, you may need to ensure the crank s dimensions (e.g., main journal spacing, rod journal size) match the block s specifications. Some aftermarket blocks are designed with specific cranks in mind, which could limit flexibility.

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### **Ending Conclusion:**

The **Molnar 400-3750CB6F-585 forged crank** is an excellent choice for **high-performance, high-stress applications**, particularly in **big-block Chevy engines** running aggressive cams, forced induction, or extreme power levels. Its forged construction, precision balancing, and reliability make it a top-tier option for builders who prioritize durability and performance. However, the **high cost and weight** may not justify the investment for **mild street engines or budget builds**.

If your engine is **heavily modified, runs nitrous, or is part of a competition setup**, the Molnar crank is a **strong recommendation**. For **stock or mildly tuned engines**, a **high-quality cast crank** (e.g., from Clevite, Scat, or Eagle) would likely provide adequate performance at a lower cost.

### **Final Recommendation:** - **Buy the Molnar crank if:**

- You re building a **high-performance or race engine** (e.g., drag racing, circle track, forced induction).

- You want **maximum durability and reliability** under extreme conditions.

- Your budget allows for the premium investment in a **long-term, high-revving, or high-torque application**.

- **Avoid the Molnar crank if:**

- Your engine is **stock or mildly modified** with no forced induction or aggressive cams.

- You re working with a **tight budget** and can achieve similar results with a **high-quality cast crank**.

- You re unsure whether the crank s strength is necessary for your specific power goals.

For most **serious performance builds**, the Molnar crank is a **worthwhile upgrade** that pays off in engine longevity and peace of mind. For everything else, a **balanced approach** matching the crank to the engine s actual needs is the best strategy.

Details:

Manufacturer: Molnar Technologies. Crankshaft - 3.750 in Stroke Internal Balance Forged Steel 2-Piece Seal 400 Mains Small Block Chevy Each.

part #: 4003750cb6f585 prices

  • $1080.99-$1169.60

specifications cranshafengin:

  • for models: 750, 400
  • brand: Molnar Technologies
  • mpn: 400-3750cb6f-585
  • part type: Crank
  • performance part: Yes

offer cranshafengin:

  • availability: In Stock
  • sold: 0
  • started: March 30, 2026
  • quantity: 2
  • options: Ship-to-home

returns cranshafengin:

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

shipping cranshafengin:

  • transit: 2-5 Days
  • type: Fixed
  • cost: $0.00
  • service: Standard
  • class: Standard

payments cranshafengin:

  • wallet: Paypal
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  • credit card: Mastercard

general cranshafengin:

  • Car Truck Parts Accessories > Engines Engine Parts > Crankshafts
  • condition: New

seller cranshafengin:

  • # reviews: 125765
  • city: San Leandro, California
  • rating: 99.8%
for models: 750, 400, part type: crank, performance part: yes,
category: auto parts > car truck parts accessories > engines engine parts > crankshafts, sku: 19581340841972722,
Molnar Technologies 400-3750CB6F-585 Is Similar To:
cranshafengin logo
3 offers $1080.99–$1169.60 USD
  • New. Offer #1 priced at $1114.88 + $0.00 shipping estimate = $1114.88* total. Crankshaft - 3.750 in Stroke - Internal Balance - Forged Steel - 2-Piece Seal - 400 Mains - Small Block Chevy - Each. Manufacturer: Molnar Technologies.FREE SHIPPING
  • New. Offer #2 priced at $1169.60 + $0.00 shipping estimate = $1169.60* total. Finish: Natural. Mains: 400.FREE SHIPPING
  • New. Offer #3 priced at $1080.99 + $0.00 shipping estimate = $1080.99* total. Crankshaft - 3.750 in Stroke - Internal Balance - Forged Steel - 2-Piece Seal - Small Block Chevy - Each.FREE SHIPPING

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