Cummins 4BT 8V 3933370 Loaded Complete Reinforced New Cylinder Head

Introducing the Cummins 4BT 8V 3933370 Cylinder Head from Heavy Duty Parts Company – a reinforced, redesigned, and reinvigorated brand-new cylinder head for the workhorse of the industries, the Cummins 4BT. Our cylinder head has been expertly redesigned to address the common flaws of the 4BT head, such as cylinder head cracking and premature valve train failure.

This heavy-duty aftermarket casting is engineered to be thicker internally in the crack-prone areas of the head and features a higher nickel content in the cast iron for enhanced durability. Our Cummins 4BT 8V 3933370 Cylinder Head comes fully assembled with valves, springs, retainers, valve locks, new high-temp Viton valve stem seals, and standard size cam bearings installed. It’s ready to install straight out of the box and built to perform.

Technical Specifications:

Fits: Cummins 4BT 3.9L engines

Displacement: 3.9L

Year range:  1984-2000

Engine type: Diesel

Cylinders: 4

Engine serial numbers: 3933370, 3903920 3932011, 3920005, 3966450, 3910275, 3800338, 3909947

Premium Cummins 4BT 3933370 Loaded Complete Reinforced New Cylinder Head

Description:

Unlock the full potential of your Cummins 4BT engine with our top-of-the-line, premium-quality 3933370 Loaded Complete Reinforced New Cylinder Head. Crafted with precision engineering and manufactured to the highest standards, this cylinder head is designed to deliver unmatched performance, durability, and reliability.

Key Features:

• Enhanced Reinforcement: Engineered with reinforced materials and advanced construction techniques, this cylinder head offers exceptional strength and durability, ensuring long-lasting performance even under the most demanding conditions.
• Complete Solution: The 3933370 Loaded Complete Reinforced New Cylinder Head comes fully loaded with all necessary components, including valves, springs, seals, and guides, providing a comprehensive solution for your engine rebuilding needs. This saves you time and hassle by eliminating the need to source individual parts separately.
• Precision Machined: Each cylinder head is precision machined to exact specifications, guaranteeing optimal fitment and seamless integration with your Cummins 4BT engine. This ensures maximum efficiency and performance, allowing your engine to operate at its peak potential.
• OEM Compatibility: Designed to meet or exceed OEM standards, this cylinder head is fully compatible with Cummins 4BT engines, ensuring a perfect fit and reliable operation. Whether you’re replacing a worn-out cylinder head or upgrading for enhanced performance, you can trust in the quality and compatibility of our product.
• Quality Assurance: Rigorously tested and inspected at every stage of production, our cylinder heads undergo stringent quality control measures to ensure unparalleled reliability and performance. You can have complete confidence in the quality and durability of our product, backed by our commitment to excellence.
• Easy Installation: With its plug-and-play design, installation of the 3933370 Loaded Complete Reinforced New Cylinder Head is quick and straightforward, minimizing downtime and getting your engine back up and running in no time. Whether you’re a professional mechanic or a DIY enthusiast, you’ll appreciate the ease of installation and the superior performance it delivers.

Upgrade your Cummins 4BT engine with confidence and experience the difference that our premium-quality 3933370 Loaded Complete Reinforced New Cylinder Head can make. Engineered for excellence and built to last, it’s the ultimate choice for enthusiasts and professionals alike who demand nothing but the best for their engines. Order yours today and unleash the full potential of your Cummins-powered vehicle.

Purchase and Shipping

We offer competitive pricing, and fast handling and shipping times. For more information on shipping times and costs, please visit our shipping policy page here: FAQ

Additional Info

Check out Cummins Official Website here.

Cummins 4BT 8V 3933370 Loaded Complete Reinforced New Cylinder Head

Core Return Required

Heavy Duty Parts Company – Core Returns Policy

Effective December 17, 2025

At Heavy Duty Parts Company, core returns are essential to our ability to provide high-quality, cost-effective cylinder heads. Returned cores supply critical components—such as keepers, springs, and retainers—that are vital to proper engine performance and allow us to maintain OEM-level quality.

No Upfront Core Charge

Unlike many suppliers, we do not charge a core fee upfront. Instead, we rely on customers to return their used cores within the required timeframe.

Core Return Requirements

• Cores are due within 30 days of the purchase date

• If a core is not returned within 60 days, the product warranty is void

• Unreturned cores will be charged as follows:

  • Cylinder heads under $600: $200 per unreturned core

  • Cylinder heads $600 and above: $400 per unreturned core

Customers needing additional time may contact us to request an extension. Approved extensions will prevent core charges from being applied.

Core Return Process

Cylinder heads are shipped with prepaid core return labels included in packets attached to the outside of each box. If labels are missing, customers should contact us for replacements prior to returning the core.

Core Eligibility

Some cylinder heads do not require a core return. In certain cases, core requirements may be waived at our discretion.

Why Core Returns Matter

• Reused core components help maintain OEM-quality standards

• Core returns allow us to keep pricing competitive

• Recycling cores supports sustainability by reducing waste and conserving resources

This policy applies to all purchases made on or after December 17, 2025.

Send Back All Components

To ensure the quality and integrity of our remanufacturing process, we ask that you return all components that were originally included with your new cylinder head. This includes items such as:

• Rocker arms
• Camshafts (if applicable)
• Any other hardware that came with your purchase

Easy & Free Core Return Process

• Each purchase includes a prepaid core return label in a plastic sleeve on the box.
• Simply pack your core with all included components, attach the label, and drop it off with the carrier—no extra cost to you.
• Returned cores undergo inspection and recycling, ensuring maximum efficiency.

Customer Partnership & Sustainability

By returning your core and its components, you help maintain a reliable supply chain, ensuring we can continue offering top-quality products at the best prices. This process not only benefits your wallet but also contributes to a greener and more efficient automotive industry.

We appreciate your support in keeping our business and the industry running smoothly!