3933370 | Cummins 4BT 8V New Cylinder Head +60lbs Performance Valve Springs| 3903920 | No Core Required

3933370 | Cummins 4BT 8V New Cylinder Head +60lbs Performance Valve Springs

Reinforce your engine with our redesigned Cummins 4BT 8V cylinder head, featuring upgraded 60lb performance springs for superior valvetrain control and high-boost reliability.

This is a brand-new, heavy-duty aftermarket casting specifically engineered to address the common cracking issues of the factory 4BT heads. By increasing internal thickness in crack-prone areas and utilizing a higher nickel content in the cast iron, this head provides unmatched durability for industrial, automotive, and marine applications.

🛠️ In-House Machining Process

• Debris-Free Preparation: Every new casting is chemically cleaned and blown out to remove all residual machining oils and manufacturing debris. This ensures your engine’s oiling system remains uncontaminated from the first start-up.
• In-House Precision Machining: Unlike “shelf-stock” heads, we perform all final machine work in-house. This includes final guide sizing and precision valve seat cutting to ensure perfect geometry and clearances.
• Pressure & Integrity Testing: To go beyond the factory standard, we pressure-test every head to 60 PSI. This verifies that the casting is free of porosity leaks or internal defects that could compromise the cooling system.
• Dimensional Inspection: Our technicians perform a multi-point inspection of the gasket-sealing surface. This ensures the head is perfectly flat and meets tight OEM tolerances for a flawless fit.
• Professional Assembly & Setup: Features +60lbs Performance Valve Springs, Viton high-temp seals, and precision-installed cam bearings. The assembly is verified in a clean-room environment to ensure it is ready for high-torque demands.
• Vacuum-Seal Verification: Every intake and exhaust port is Vacuum Tested. This guarantees a 100% airtight seal between the valves and seats, ensuring maximum compression and peak performance right out of the box.

📊 Technical Specifications

• Condition: Brand New Reinforced Casting
• Engine Compatibility: Cummins 4BT 3.9L (8-Valve)
• Spring Upgrade: +60lbs Performance Springs (Ideal for higher RPM and boost)
• Year Range: 1984-2000
• Seals: Premium High-Temp Viton Valve Stem Seals
• Includes: Fully Loaded (Valves, Springs, Retainers, Locks, and Cam Bearings installed)
• Casting Material: High-Nickel Content Cast Iron for enhanced heat resistance
• Serial Number Compatibility: 3933370, 3903920, 3932011, 3920005, 3966450, 3910275, 3800338, 3909947

🚘 Common Applications

Direct fit for Cummins 4BT 3.9L Diesel Engines:

• Step Vans / Delivery Trucks: Popular 4BT P-Pump and VE-Pump applications
• Off-Road & Industrial: Excavators, wood chippers, and generators
• Custom Builds: 4BT Swaps into Jeeps, Land Cruisers, and Pickups
• Marine Engines: 4BT marine configurations