Summit Racing™ Camshafts

KEY POINTS SUMMARY:

• Camshaft grinds shift the engine's power band, allowing for more low-end torque, high-rpm power, or a broader range of usable power.

• Camshafts with longer durations and increased overlap produce higher rpm performance with a choppier idle, while those with wider lobe separation angle and shorter durations maintain good idle quality and a broad torque curve.

• Valve overlap can affect engine vacuum, which is essential for power brakes and other vacuum-assisted systems. Excessive overlap can reduce vacuum, potentially affecting brake performance.

• To maximize a cam’s performance potential, it should be paired with the appropriate intake, exhaust, and static cylinder compression.

• An engine with excessive overlap and low static compression is often described as “over-cammed,” which produces that classic choppy idle but at the expense of performance at low rpm.

Summit Racing Camshafts offer a wide range of designs for everything from daily street performance to extreme racing setups. Our selection of budget-friendly options covers a huge variety of popular domestic engines.

Our camshafts improve engine performance by optimizing the timing and lift of the engine's valves. Camshaft grinds shift the engine's power band, allowing for more low-end torque, high-rpm power, or a broader range of usable power. This improved valve action results in enhanced horsepower, torque, and overall engine responsiveness. Summit camshafts are available in a variety of options, including hydraulic flat tappet, solid flat tappet, and hydraulic roller designs for both original roller cam blocks and retrofit applications. This variety allows users to select a camshaft that best meets their specific performance goals.

Additionally, Summit Racing offers the accessories you need, including installation kits, lifters, valve springs, pushrods, plus detailed specifications to help you select the proper camshaft for your project.

When choosing a camshaft, always remember to consider factors like compression ratio, cylinder head flow, and intended use to ensure optimal compatibility with your engine setup. There are several aspects to a camshaft that affect engine operation and fitment, such as duration, lift, lobe separation, and more.

Camshaft Lift

Lift is measured in inches and determines how far the valve is raised from its seat. There are two standard lift measurements: lobe and gross. Lobe lift is measured at the nose of the lobe, minus the base circle. Gross lift can be calculated by multiplying the lobe lift by the rocker arm ratio. This calculation represents the actual lift at the valve. Lifting a valve beyond the cylinder head's capability is counterproductive.

Camshaft Duration

Duration describes how long the valve is open and is measured in degrees of crankshaft rotation. The measurement comes in two forms: “advertised duration” and “duration at 0.050" lift.” The advertised duration will always be larger since it starts lower on the lobe, closer to the base circle. When comparing camshafts, using duration at 0.050" lift is a more accurate comparison since it is a standardized measurement across all camshafts. Short-duration cams boost low-speed torque and throttle response, while long-duration cams enhance high-rpm power.

Lobe Separation Angle (LSA)

Lobe separation angle (or “LSA”) measures the angle, in degrees, between the peak lift of a camshaft's intake and exhaust lobes. While lift and duration provide details about individual lobes, LSA illustrates how those lobes relate to each other. A wider LSA provides a broad torque curve—ideal for trucks or street cars—while a narrower LSA is better for higher rpm and a tighter torque band in performance and race engines.

Overlap

Overlap is the period where both intake and exhaust valves are open simultaneously. More overlap can improve exhaust scavenging at high rpm, but may negatively impact idle vacuum, low-end power, and power brake operation.

Piston-to-Valve Clearance

Piston-to-valve clearance is the distance between the piston and the engine valves. This space is crucial to prevent collisions between the two during operation. If the clearance is insufficient, it can result in severe engine damage. It's essential to check this clearance, especially when building a new engine or modifying components such as the camshaft, cylinder head, or pistons.

Supporting Modifications

There are several vital engine modifications you should consider when selecting a performance camshaft. Upgrades such as performance valve springs, retainers, and intake and exhaust systems are often needed to ensure reliable operation and optimal engine performance. Other considerations include the stall speed of your vehicle’s automatic transmission converter and the rear-end gear ratio.

Proper Camshaft Break-In

Following proper break-in procedure is crucial, especially for flat tappet camshafts. It ensures the lifters properly mate with the cam lobes, preventing premature wear. This process establishes the correct wear pattern and allows the lifters to rotate, distributing oil and reducing friction. Without proper break-in, lifters can scuff or flatten the cam lobes, resulting in decreased performance and potential failure. Always be sure to follow manufactures camshaft break in procedures.

FAQ Section:

Q. Do camshafts add horsepower?

A. Camshafts can boost horsepower in an engine, but the increase ultimately depends on the camshaft design, engine type, tuning, and supporting modifications. Camshafts control valve timing and duration, impacting airflow and performance. Upgrading to a performance camshaft can enhance your engine’s efficiency, throttle response, and power across the rpm range.

Q. What are the drawbacks of replacing your engine’s camshaft?

A. The biggest risk is over-camming your engine. Many enthusiasts enjoy a choppy idle, but they often overlook that increased valve overlap can cause lower rpm reversion, resulting in sluggish throttle response and poor brake performance. An aggressive camshaft may sound appealing, but it can lead to disappointing low-rpm performance, especially without sufficient static compression. Performance cams usually require a variety of supporting modifications to perform optimally, including proper differential gearing and a high-stall torque converter. Additionally, performance camshafts can increase wear on engine components like lifters and bearings if not properly matched. It's essential to consider the basic rpm range and usage, as well as matching components, when selecting a cam.

Q. What is the difference between hydraulic flat tappet, roller, and solid cams?

A. Hydraulic flat tappet cams feature hydraulic lifters that use oil pressure to automatically maintain zero valve clearance at the rocker, making them ideal for reliable street applications.

Solid cams utilize solid lifters without hydraulic adjustment, requiring periodic valve clearance adjustments. They are favored in high-performance and racing applications for optimal power and precise valve timing, especially at high rpms.

Roller cams use a roller lifter that reduces friction with the cam lobes, allowing for faster valve opening. They are well-suited for performance applications, including racing and high-performance street cars. They’re available in hydraulic or solid grinds.

Q. Which cams work well with forced induction—like a mild turbo on an LS?

A. Summit Racing Pro LS Turbo Cams are designed specifically for forced induction applications. Our Stage 1 LS Turbo camshaft (SUM-8715R1) provides quick spool-up and strong mid-range and top-end power, with a noticeable lope. It’s recommended for single-turbo applications and pairs well with a 2,500 rpm stall converter, though it's not required.

Our Summit Stage 2 LS Turbo camshaft (SUM-8706R1) focuses on quick spooling with reduced reversion from high turbine inlet pressures. It offers excellent mid-range and top-end power and is a high-lift alternative to the our Stage 4 truck cam, maintaining stability to 7,000 rpm.

Q. Can my stock valve springs handle a cam with .540" lift, or do I need to upgrade the valvetrain?

A. Using stock valve springs with a .540" lift cam is generally not recommended, especially for high-rpm driving or aggressive performance applications. While some stock springs may manage this lift, they risk operating at their limits, leading to valve float, wear, or breakage. Although it might seem cost-effective to stick with stock springs, it can result in higher expenses over time. Choosing the right valvetrain components is crucial for reliable performance.