Understanding Camshafts and Their Role in Engine Performance

The camshaft is often called the brain of an engine because it dictates when the intake and exhaust valves open and close. In a pushrod V8 like the one in a Fox-body or SN95 Mustang, the camshaft sits inside the engine block and uses lobes to actuate lifters, pushrods, and rocker arms. The shape, size, and timing of those lobes determine the engine's personality — from a silky smooth idle to an aggressive lope that turns heads at a car meet. For my 5.0L V8 Mustang, swapping in a Summit Racing camshaft unlocked a clean 30 horsepower gain that completely transformed the driving experience. This article will walk through the selection process, the science behind camshaft specifications, and the real-world results you can expect from a carefully chosen performance cam.

Why Upgrade Your Camshaft?

While a stock camshaft is designed for a balance of emissions, fuel economy, and smooth idle, a performance camshaft shifts that balance toward power. The benefits go beyond just raw horsepower numbers:

  • Increased Horsepower and Torque Curve Shift: A performance cam can move the power band higher into the RPM range, adding peak horsepower while also improving torque where you need it most — often in the mid-range for street driving.
  • Improved Throttle Response: With more aggressive lobe profiles, the engine reacts faster to throttle inputs, making the car feel lighter and more eager.
  • Enhanced Exhaust Note: The increased overlap (when both intake and exhaust valves are open simultaneously) creates that iconic, choppy idle that performance enthusiasts love.
  • Better Overall Efficiency at Higher RPM: For track or autocross use, a cam tuned for high-RPM breathing can significantly reduce pumping losses at sustained high speeds.

In my case, the Summit Racing camshaft not only added 30 hp but also broadened the torque curve so the Mustang pulled hard from 3,000 rpm all the way to its 6,200 rpm redline. That's the kind of improvement that makes every shift feel like a rush.

Key Camshaft Specifications to Understand

Selecting the right camshaft requires understanding a few critical numbers. These specifications determine where the engine makes power and how it behaves at idle and part throttle.

Lift (Valve Lift)

Lift is how far the valve opens off its seat. Measured in inches (or millimeters), higher lift allows more air and fuel into the cylinder and helps exhaust gases escape. However, lift must be matched to your cylinder head's flow capability and your valve train's mechanical limits — too much lift can coil-bind springs or cause piston-to-valve interference. The Summit Racing cam I used had a .550-inch lift, which worked perfectly with my aftermarket valve springs and stud girdle.

Duration (Degrees of Crankshaft Rotation)

Duration is how long, in degrees of crankshaft rotation, the valve is held open. Duration affects the RPM range: longer duration shifts power higher; shorter duration favors low-end torque. Advertised duration is typically measured at .050-inch lift for consistent comparison. My cam had 230 degrees of intake duration and 236 degrees of exhaust duration at .050-inch lift, placing the power band between 2,500 and 6,500 rpm — ideal for a street/strip Mustang.

Lobe Separation Angle (LSA)

LSA is the angle in cam degrees between the intake and exhaust lobe centerlines. A tighter LSA (108–112 degrees) increases overlap, which can boost top-end power but may hurt vacuum and idle quality. A wider LSA (114–118 degrees) creates a broader torque curve and smoother idle. My Summit Racing cam used a 112-degree LSA, which struck an excellent balance for a car that sees both daily highway cruising and weekend track passes.

Camshaft Material and Grinding

Most performance camshafts are made from cast iron or steel billet. For street-driven cars, a cast iron cam with a hardened lobe surface is perfectly adequate. Summit Racing offers both flat tappet and roller camshafts. Roller cams reduce friction and allow more aggressive profiles, but they cost more and often require a different lifter setup. Since I was upgrading from a flat tappet, I chose a Summit Racing hydraulic roller cam for its durability and slightly more aggressive lobe design.

Factors to Consider When Selecting a Camshaft

Choosing a cam isn't about picking the biggest numbers — it's about matching the cam to your entire engine combination. Here are the factors I weighed before buying.

Engine Type and Displacement

Turbo, supercharged, and naturally aspirated engines respond differently to cam timing. For my naturally aspirated 5.0L V8, a cam with moderate lift and duration gave the best all-around street/strip performance. Larger displacement engines (e.g., 347 or 408 strokers) can use more duration and lift because they have more cubic inches to fill.

Intended Use: Street, Strip, or Both

If the car is a daily driver, you'll want a cam that maintains good vacuum for power brakes and has a manageable idle. A dedicated track car can tolerate a radical cam with lope and high stall converter. My Mustang sees about 60% street and 40% track, so a "street/strip" cam was the right choice. Summit Racing's camshaft catalog actually includes detailed notes about idle characteristics and vacuum levels for each part number.

Valve Train Compatibility

High lift and aggressive ramps require stronger valve springs, retainers, and possibly guide plates. I upgraded to Summit Racing double springs and hardened pushrods to prevent float and reduce wear. Also ensure your pistons have valve reliefs that clear the new cam — I checked piston-to-valve clearance with clay before final assembly.

Gearing and Torque Converter

A cam that makes peak power at 6,000 rpm won't be happy with a 2,200 rpm stall converter and 2.73 rear gears. Ideally, your converter stall speed and rear gear ratio should match the cam's power band. I already had 3.73 gears and a 3,000 rpm stall converter, which paired well with the Summit cam's power curve.

Compression Ratio

Higher compression (9.5:1 and above) works well with longer duration cams because the later intake valve closing effectively lowers dynamic compression, preventing detonation. My 9.5:1 static compression was a good match for the 230/236 duration cam.

My Experience with Summit Racing Camshaft Installation

After extensive research, I ordered a Summit Racing SUM-8600 (a commonly recommended part for 5.0L street/strip builds). The cam arrived well-packaged with a break-in lube recommended for the lifter bases. Here's a step-by-step overview of the installation process and the results.

Installation Process

I performed the swap in my garage over a weekend, using a lift and standard tools. Safety note: always disconnect the battery and drain the coolant before opening the cooling system.

  • Drained the engine oil and removed the intake manifold, valve covers, timing cover, and harmonic balancer.
  • Removed the rocker arms, pushrods, and lifters, keeping them in order for reinstallation (though using new lifters is recommended for a cam swap).
  • Removed the timing chain and gear set, then carefully slid the old camshaft out through the front of the engine block.
  • Lubricated the new Summit Racing cam lobes with the provided assembly lube and installed it gently to avoid damaging the bearings.
  • Installed a new double-roller timing chain with the cam timing set to the factory marks (I also verified degreeing later).
  • Installed new lifters, pushrods, Summit Racing double valve springs, and rockers. Adjusted the valve lash properly.
  • Reassembled the front of the engine, filled with new oil (5W-30 conventional for break-in), and started the engine.

One challenge I encountered was that the new cam required deeper valve reliefs in the pistons due to the increased lift. I had to swap to forged pistons with larger reliefs, which added cost and time but was necessary for clearance. If you have stock pistons, verify clearance before ordering.

Performance Gains and Dyno Results

After a proper break-in of 20 minutes at varying RPM (avoiding idle), I took the Mustang to a local chassis dyno. The results were impressive:

  • Peak Horsepower: The old cam produced 280 hp at the rear wheels. After the Summit Racing swap, the car put down 310 rwhp — a solid 30 hp gain. The peak power moved from 5,200 rpm to 5,800 rpm.
  • Torque Curve: Average torque increased 25 lb-ft from 3,000–5,500 rpm, with a peak of 340 lb-ft at 4,500 rpm compared to 315 lb-ft before.
  • Idle Quality: The car idles at 850 rpm with a noticeable but manageable lope. Vacuum is 12 in-Hg, which is fine for power brakes on my car.
  • Sound: The exhaust note gained a deep, throaty rumble that sounds aggressive without being obnoxious.

On the street, the Mustang feels visibly quicker — it pulls hard from 2,500 rpm and doesn't fall flat up top. The 30 horsepower is definitely noticeable in a 3,300-pound car, especially at highway passing speeds.

Real-World Update: After 10,000 Miles

I've now put over 10,000 miles on the Summit Racing camshaft, including several autocross and drag strip events. The cam has held up perfectly — no lobe wear, stable valve lash, and consistent performance. Fuel economy dropped about 1 mpg, but that's expected with the more aggressive idle and higher RPM driving. I attribute the reliability to using quality lifters and proper break-in procedures.

Camshaft Selection Tips for Your Mustang Build

Based on my experience, here are actionable steps to pick the right camshaft:

  1. Define your use case. Be honest: is this a daily driver, weekend warrior, or track-only car? Summit Racing's online cam selector tool lets you filter by engine, vehicle, and intended use.
  2. Know your current specs. Check cylinder head flow numbers, compression ratio, intake and exhaust system capabilities. A cam that outflows your heads won't show its full potential.
  3. Consult tech support. Summit Racing has knowledgeable product specialists. I called their tech line before purchasing, and they confirmed the SUM-8600 was ideal for my 302 with TFS heads and Holley carburetor.
  4. Consider a cam kit. Summit offers complete camshaft kits that include lifters, springs, retainers, and pushrods — this simplifies the buy and ensures compatibility.
  5. Don't skip the tune. A cam swap demands retuning the carburetor (or EFI tuning) and ignition timing. I spent a session on a wideband dyno dialing in the air/fuel ratio for maximum power.
  6. Check valve clearance. Use modeling clay on the pistons with the head off to verify no contact. Many Summit cams include clearance recommendations in the instructions.

For more in-depth camshaft theory, I recommend reading the Engine Builder Magazine camshaft basics article — it explains lift, duration, and LSA with dyno charts that help visualize the trade-offs.

Conclusion

Upgrading to a Summit Racing camshaft was one of the most rewarding modifications I've made to my V8 Mustang. The 30 horsepower gain translated into a car that's genuinely faster and more exciting to drive. Beyond the numbers, the engine's character changed — it revs eagerly, sounds purposeful, and rewards driver input. The selection process forced me to learn the fundamentals of camshaft design, which has made me a more knowledgeable builder. Whether you're considering a cam for your Fox Body, SN95, or even a modern Coyote, take the time to research, call Summit Racing's tech support, and match the cam to your entire combination. The result will be a power increase that feels factory — just more intense. If you're ready to start shopping, check out Summit Racing's full cam selection for Ford Mustangs and read the customer reviews for real-world feedback.