BC8810 – Mitsubishi 4G63/Evo VIII Adjustable Cam Gears

In the realm of high-performance 4G63 engine building, absolute control over valve timing is not a luxury—it is a fundamental requirement for unlocking power, optimizing curve, and correcting factory tolerances. The Brian Crower BC8810 Adjustable Cam Gears stand as the definitive solution for the Mitsubishi Evolution VIII and its foundational 4G63 platform. Engineered from the ground up for the serious tuner and builder, these are not mere cosmetic upgrades but critical precision instruments. They provide the granular adjustability needed to perfectly synchronize camshaft position with piston movement, a non-negotiable step for anyone pursuing significant horsepower gains, aggressive camshaft upgrades, or simply restoring optimal factory timing after a rebuild. This is the tool that bridges the gap between a running engine and a perfectly tuned engine.

The Critical Role of Adjustable Cam Timing

Factory cam gears are pinned and keyed, locking camshaft timing into a single, compromise-oriented position designed for emissions, drivability, and a broad power band. The BC8810 Adjustable Cam Gears revolutionize this static relationship. By allowing independent adjustment of the intake and exhaust camshafts—typically up to ±15 degrees of movement—they enable a tuner to manipulate the engine’s volumetric efficiency and personality. Advancing or retarding cam timing directly affects when the valves open and close relative to the piston’s position in the cylinder. This control is paramount for optimizing power at specific RPM ranges, mitigating turbo lag, accommodating aftermarket camshafts with altered lobe separation angles, and correcting chain stretch or block/head machining that has altered the factory timing baseline. Without this adjustability, you are leaving significant power and engine safety on the table.

Brian Crower Engineering: Precision Billet Construction

BC’s reputation is built on components that withstand extreme environments, and the BC8810 gears are a testament to this philosophy. Machined from a solid block of 6061-T6 billet aluminum, each gear offers a monumental increase in strength and dimensional stability over cast or powdered metal OEM units. The CNC machining process ensures tooth profiles are perfect, concentricity is absolute, and the mating surface to the camshaft is flawlessly flat to prevent any wobble or harmonic imbalance. The adjustment mechanism itself is a study in robust design, featuring large, knurled aluminum locking nuts that secure the adjustable outer ring to the main hub via high-grade alloy steel hardware. This design prevents slip under high-RPM harmonics and belt tension, a common failure point in inferior designs. The laser-etched degree markings are precise and clear, allowing for repeatable, accurate adjustments.

Key Performance Benefits

• Maximize Horsepower & Torque: Fine-tune the valve events to optimize cylinder filling and scavenging for your specific combination of turbo, cams, and fuel.
• Customize Power Band Characteristic: Shift the power curve; advance timing for more low-end torque, or retard for increased top-end horsepower.
• Essential for Aftermarket Camshafts: Correctly dial in the lobe centerlines of performance cams from Brian Crower or other manufacturers to realize their full potential.
• Correct Timing Distortion: Compensate for timing belt stretch, block/head resurfacing, or manufacturing tolerances to restore precise cam-to-crank alignment.
• Improved Engine Safety: Prevent piston-to-valve contact during high-lift cam or high-compression builds by carefully retarding timing during initial startup and tuning.
• Superior Material & Construction: 6061-T6 billet aluminum provides immense strength and reduces rotating mass compared to stock gears, improving engine response.

Installation and Tuning Methodology

Installation requires mechanical competency and precision. The procedure involves locking the engine at top dead center (TDC), removing the valve cover, accessory belts, and the factory timing belt and gears. The BC8810 gears are installed using the original camshaft keys. Critical Note: Before rotating the engine, it is imperative to manually verify piston-to-valve clearance by barring the engine over slowly, especially when using aftermarket camshafts or altered timing. Final tuning is an iterative process performed on a dynamometer. The tuner will make incremental adjustments (often in 2-4 degree steps) to both intake and exhaust gears while monitoring the power curve, air/fuel ratios, and often exhaust gas temperatures. The goal is to find the “sweet spot” where the engine makes the broadest, safest power. For an in-depth technical exploration of cam timing effects on turbocharged engines, refer to this authoritative resource on understanding camshaft timing principles.

Vehicle Fitment & Compatibility

Primary Application: Mitsubishi Evolution VIII (2003-2005).
Core Engine Compatibility: All 4G63 (DOHC) engines from 1990-2005, including those found in:
– Mitsubishi Eclipse GS-T & GSX (1990-1999)
– Eagle Talon TSi (1990-1998)
– Plymouth Laser RS Turbo (1990-1994)
Note: Early 6-bolt (1990-1992) and later 7-bolt (1992+) 4G63 engines utilize different camshaft dowel pin diameters. The BC8810 kit is designed for the later 7-bolt style camshafts (12mm dowel pin), which are standard on the Evolution VIII and most 1992+ applications. Users with 6-bolt engines (10mm dowel) must verify camshaft compatibility or source the appropriate dowel pins.

Technical Specifications

The Brian Crower BC8810 Adjustable Cam Gears are the professional’s choice for 4G63 engine development. They translate theoretical timing maps into real-world power, providing the robust, precise mechanical interface required to fully command one of the most capable turbocharged engines ever produced. This is not an upgrade you simply bolt on; it is a tuning parameter you harness.