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The camshaft in a 350 Small Block Chevy is a critical component that dictates your engine's power, torque, and overall character. Understanding its function and choosing the right upgrade can transform your vehicle's performance significantly.
Unlike more modern engines that might employ single overhead camshaft (SOHC) designs, where the camshaft is located within the cylinder head, the classic 350 Small Block utilizes a robust pushrod, overhead valve (OHV) configuration with its single camshaft residing in the engine block. This design has proven itself durable and highly tunable for decades, making it a favorite among enthusiasts.
Understanding Camshaft Basics for Your SBC
A camshaft's primary role is to open and close the engine's intake and exhaust valves at precise times, allowing air and fuel in and exhaust gases out. Key specifications like lift, duration, and lobe separation angle (LSA) determine how your engine breathes and performs across the RPM range. These numbers directly influence idle quality, power band, and fuel efficiency.
Lift refers to how high the valve opens, impacting the maximum amount of air that can enter or exit the cylinder. Duration measures how long the valve stays open, influencing the engine's RPM range and power characteristics. Meanwhile, the Lobe Separation Angle (LSA) affects the overlap between intake and exhaust valves, influencing idle quality, vacuum, and overall torque curve.
Types of Camshafts for the 350 Small Block
When upgrading your 350 Small Block Chevy, you'll encounter several camshaft types, each with distinct advantages. Hydraulic flat tappet cams are the traditional choice, affordable and effective for many street applications.
However, modern hydraulic roller camshafts offer significant benefits, including higher lift, quicker ramp rates, and reduced friction, leading to more power and better longevity without the break-in concerns of flat tappets. Mechanical roller cams are typically reserved for high-performance racing applications, offering aggressive profiles but requiring more frequent maintenance and specialized valvetrain components.
Choosing the Right Camshaft for Your Application
Selecting the ideal camshaft for your 350 SBC requires careful consideration of several factors beyond just peak horsepower numbers. Your engine's intended use – whether it's a daily driver, a weekend cruiser, a drag strip warrior, or a towing rig – should guide your decision. A street engine generally benefits from a cam that prioritizes low-to-mid range torque, while a race engine needs profiles optimized for high-RPM power.
Crucially, you must match your camshaft choice with other engine components like cylinder heads, compression ratio, transmission type, torque converter stall speed, and rear gear ratio. A cam that's too aggressive for your cylinder heads or too mild for your compression can lead to suboptimal performance and even drivability issues. Consulting with engine builders or using cam selection software can help ensure a harmonious setup.
Key Factors to Consider:
Intended Use: Determine if your primary goal is street driving, drag racing, road course, or heavy towing. Each application demands a specific cam profile that delivers power where it's most needed.
Compression Ratio: Higher compression ratios can handle more aggressive camshaft profiles with longer durations. Mismatched compression and cam can lead to poor idle and loss of low-end torque.
Cylinder Heads: The flow characteristics of your cylinder heads (stock, aftermarket, porting) directly impact how much air your engine can ingest and expel. A high-lift cam on restrictive heads won't yield its full potential.
Drivetrain Components: Consider your transmission (manual vs. automatic), torque converter stall speed for automatics, and rear axle gear ratio. An aggressive cam will likely require a higher stall converter and steeper gears to launch effectively.
Installation and Break-In for Your New Camshaft
Proper installation of your new 350 Small Block Chevy camshaft is paramount for its longevity and performance. Always ensure all components are clean, adequately lubricated with cam lube, and torqued to factory specifications.
For hydraulic flat tappet camshafts, a critical break-in procedure is required to properly seat the lifters and prevent premature lobe wear. This typically involves running the engine at varying RPMs (2000-2500 RPM) for 20-30 minutes immediately after start-up, using a high zinc oil or zinc additive. While hydraulic roller cams don't require this specific break-in, proper lubrication and careful initial start-up are always essential.
Maximizing Performance with Your Camshaft Upgrade
A camshaft upgrade is often the cornerstone of a significant performance improvement in a 350 Small Block Chevy. It's a key modifier that can shift your engine's power band, increasing horsepower and torque where you want it most.
Beyond the camshaft itself, consider supporting modifications like an improved intake manifold, a properly sized carburetor or fuel injection system, and a free-flowing exhaust. These components work in synergy with your new cam to unlock your engine's full potential, ensuring that your investment translates into tangible on-road or track performance.
In conclusion, a carefully chosen and properly installed camshaft is one of the most effective ways to enhance your 350 Small Block Chevy's performance. By understanding the basics, considering your specific needs, and matching components, you can transform your engine into a powerhouse tailored to your driving style.
