BC0140 – Mitsubishi 6G72 (DOHC) Spring/Titanium Retainer Kit

In the high-stakes realm of forced induction and elevated RPM, the factory valvetrain is often the first critical system to fail, acting as a governor on an engine’s true potential. For the legendary Mitsubishi 6G72 DOHC, the heart of icons like the 3000GT VR-4 and Stealth R/T Turbo, unlocking reliable power requires a foundation built to withstand extreme cylinder pressure and inertial forces. The BC0140 Spring and Titanium Retainer Kit from Brian Crower is not merely an upgrade; it is a complete valvetrain reinforcement system engineered to transform the 6G72’s top-end from a liability into a bastion of reliability. Designed for compatibility with high-lift Brian Crower camshafts and aggressive boost profiles, this kit replaces the marginal OEM components with precision-matched, high-pressure springs and featherweight titanium retainers. The result is absolute valve control at RPM thresholds far beyond stock, eliminating float and bounce to safeguard your investment and unleash the full, uncompromised performance of your twin-turbo or built NA 6G72.

Engineering for Absolute Valve Control

The primary mission of the BC0140 kit is to maintain constant contact between the camshaft lobe, follower, and valve stem—a principle known as valve control. Under high boost or at high RPM, the stock valve springs can become overwhelmed. They can’t close the valve quickly enough against the immense cylinder pressure or the inertia of the valvetrain components, leading to valve float. This momentary loss of control causes the valve to bounce on the seat, leading to catastrophic wear, bent valves, and piston-to-valve contact. The BC0140 springs are manufactured from proprietary chrome-silicon alloy wire, wound to provide a significantly higher seat and open pressure than the factory springs. This increased pressure, combined with a linear rate, ensures the valve is slammed shut with authority at every RPM, regardless of boost level. The science is clear: controlled valves are efficient valves, allowing for precise cam timing, optimal cylinder sealing, and the ability to safely explore the upper reaches of your tachometer.

Core Benefits of the BC0140 Kit

• Eliminates Valve Float: High spring pressures prevent valve bounce, enabling stable operation at RPMs exceeding 8,000+ with compatible camshafts.
• Enables Aggressive Cam Profiles: Specifically designed to work with high-lift, long-duration Brian Crower camshafts without coil bind.
• Boosts Boost Tolerance: Increased seat pressure ensures valves seal perfectly against extreme cylinder pressures from high-horsepower turbo setups.
• Reduces Valvetrain Mass: Titanium retainers are approximately 50% lighter than steel, reducing inertial forces for higher, safer RPM limits.
• Enhances Durability: Premium chrome-silicon material offers superior fatigue resistance and heat tolerance for long-term reliability in competition or street use.
• Maintains Stock Installation Height: Designed as a direct replacement, simplifying installation without requiring machining of spring seats in most 6G72 DOHC heads.

Installation and Compatibility Considerations

While the BC0140 kit is engineered as a direct bolt-on component for the Mitsubishi 6G72 DOHC engine, professional installation is highly recommended. Critical checks must be performed to ensure a successful build. First and foremost, installing these high-pressure springs necessitates a corresponding upgrade to the valve seals and a thorough inspection of the valve guides for wear. Secondly, it is imperative to verify installed height and check for coil bind. Using a precision height micrometer, measure the installed height of each spring with the retainer locked in place. The kit is designed to work at the stock installed height, but manufacturing variances in cylinder heads can occur. Furthermore, with the valve at full lift (using a checking spring or the actual cam), you must confirm there is adequate clearance between the spring coils to prevent them from compressing solidly—a condition known as coil bind, which will destroy components. For those running exceptionally high-lift cams, machining the spring seats for deeper installation or using lash caps may be required. As a cornerstone of valvetrain geometry, understanding these principles is critical; for a deeper dive, consult authoritative resources such as this guide on valvetrain geometry basics from Engine Builder Magazine.

Comprehensive Vehicle Fitment

The BC0140 Spring and Titanium Retainer Kit is engineered specifically for the 24-valve, dual overhead cam (DOHC) variant of the Mitsubishi 6G72 engine. It is a direct-fit application for the following vehicles, crucial for both performance builds and reliability-focused renewals of aging valvetrains.

Vehicle Fitment: Mitsubishi 3000GT VR-4 (1991-1999), Mitsubishi 3000GT SL (DOHC non-turbo models), Dodge Stealth R/T Turbo (1991-1993), Dodge Stealth ES (DOHC non-turbo models). Note: This kit is for DOHC heads only and will NOT fit the SOHC 12-valve 6G72 engines found in base model Stealths, 3000GTs, or Monteros.

Technical Specifications