What Is the Point of Camming a Car?

Camming a car—installing a performance camshaft—is done to change when and how far the engine’s valves open so the engine breathes better in a specific rpm range, typically increasing horsepower and shifting the torque curve; it also gives a lumpier, more aggressive idle. In practical terms, a cam swap tailors valve timing, lift, and duration to your goals (street, track, towing, or boost), trading some drivability and emissions headroom for stronger performance where you want it.

How a Camshaft Changes Engine Behavior

The camshaft controls the opening and closing of intake and exhaust valves. By altering its profile, you reshape the engine’s airflow dynamics—how much air-fuel mixture enters and how efficiently exhaust leaves—directly affecting power, torque, idle quality, and fuel economy.

These are the core camshaft variables that determine the character of a cammed engine and explain why some setups surge at idle while others pull hard up top:

• Duration: How long a valve stays open (often quoted at 0.050-inch lift). Longer duration favors high-rpm power but weakens low-end torque and vacuum.
• Lift: How far the valve opens. Higher lift can flow more air if the cylinder head supports it; beyond that, gains diminish and valvetrain stress rises.
• Lobe Separation Angle (LSA): The angle between intake and exhaust lobes. Tighter LSA increases overlap for a choppier idle and stronger mid/high-rpm scavenging; wider LSA smooths idle and broadens the torque curve, often preferred for boost.
• Advance/Retard (Phasing): Moving the cam’s centerline changes where the power comes in—advancing can help low-midrange, retarding can help top-end.

Together, these parameters shape the engine’s “personality.” A mild cam refines responsiveness without drama; an aggressive cam moves the powerband up and introduces the signature lope and compromises at low rpm.

Why Enthusiasts Cam Their Cars

Motivations vary from measurable performance improvements to subjective enjoyment. The following factors capture the most common reasons for a cam swap:

• More peak power and torque: Unlocks airflow potential, especially on naturally aspirated V8s, when paired with proper tuning and supporting mods.
• Custom powerband: Tailors where the engine makes its best power—drag racers might target top-end, street cars often prefer a fat midrange.
• Complement to bolt-ons: Maximizes gains from headers, intake, higher compression, and cylinder head work.
• Distinctive sound: The lopey idle and sharper exhaust note are part of the appeal, though they reflect real changes in overlap and vacuum.
• Track specialization: Cams can be profiled for road course, autocross, or towing, not just straight-line speed.
• Boost optimization: Forced-induction engines benefit from wider LSA, reduced overlap, and profiles that manage reversion under pressure.

In short, camming is a strategic choice: it aligns the engine’s breathing with the driver’s priorities, whether that’s lap times, quarter-mile traps, or character.

Trade-offs and Risks

A cam swap isn’t free horsepower; it’s a rebalancing act. These are the downsides owners must weigh before committing:

• Reduced low-rpm torque and vacuum: Big duration/overlap can hurt drivability, idle quality, and power brake assist.
• Rougher idle and stalling tendencies: Aggressive profiles may need higher idle speed and careful tuning.
• More valvetrain stress: Stronger springs, proper pushrod length, and quality lifters/rockers are often mandatory.
• Emissions and inspection challenges: Many performance cams are not emissions-legal in jurisdictions requiring testing.
• Fuel economy and NVH: Expect some drop in mpg and an increase in cabin vibration and noise.
• Converter/gearing mismatch: Automatics often need a higher-stall converter; tall gearing can feel lazy off the line.
• Reliability risks if set up poorly: Insufficient spring pressure, coil bind, or piston-to-valve contact can be catastrophic.

When the cam, tune, and hardware are matched, most compromises become manageable. Mismatches are what create bad experiences.

Choosing the Right Cam

Selection should start with the whole system—engine architecture, the car’s role, and supporting components—not a single “stage” label. Consider these decision points:

• Engine type and valvetrain: Pushrod (OHV) V8s are comparatively straightforward; DOHC engines require precise timing tools and often yield smaller gains from cams alone.
• Intended use: Daily commute, canyon carving, track days, towing—each points to a different duration/LSA balance.
• Supporting mods: Heads, headers, intake, compression ratio, and throttle body dictate how much lift/duration you can use effectively.
• Transmission and gearing: Automatics may need a 2,400–3,600+ rpm stall with bigger cams; manuals may require clutch upgrades.
• Vacuum needs: Power brakes typically prefer 15–18 inHg; a vacuum pump or hydroboost can offset a lopey cam’s low vacuum.
• VVT considerations: On newer engines, you may need cam phaser limiters/lockouts and a tune; some gains are achievable via phasing alone.
• Emissions and inspection: Look for parts with approved exemptions where required; otherwise, expect to fail visual/OBD tests.
• Boost match: Turbo/supercharged builds often use wider LSA and less overlap to control reversion and keep the charge in the cylinder.

If in doubt, consult a reputable cam grinder or tuner with your full mod list and goals; a custom grind can outperform generic stages for the same money.

Typical Gains You Can Expect

Real-world gains vary by platform, spec, and tune. The examples below reflect typical ranges when the cam is matched to the combo and properly calibrated on a dyno:

• GM LS3/L99 (6.2L NA): Mild cams commonly add 30–50 whp; aggressive street cams 60–90+ whp with springs, headers, and tune.
• GM 5.3/6.0 truck LS: 20–50 whp is typical with headers and tune; drivability remains good with conservative profiles.
• Ford Coyote 5.0 (DOHC, VVT): 10–30 whp from cams alone; more with supporting headwork and intake, as the stock cams and VVT are already efficient.
• Chrysler Hemi 5.7/6.4: 25–60 whp depending on spec and bolt-ons; phaser limiters and tuning are key.
• Boosted setups: Gains depend on turbo size and backpressure. Proper boost cams improve spool and top-end, but headline dyno gains may be modest if the turbo is the bottleneck.

Numbers are guideposts, not guarantees. Cylinder head flow, compression, exhaust, and calibration quality often determine the final result more than the cam alone.

Installation and Tuning Essentials

A cam swap is more than sliding in a new stick. Reliability hinges on complementary parts, precise setup, and a thorough tune.

• Valvetrain upgrades: Valve springs matched to lift, retainers, locks, pushrods, and sometimes lifters are required to prevent float and wear.
• Timing components: New chain/belt, tensioners, and adjustable or phaser-limited sprockets as needed; always verify piston-to-valve clearance.
• Degreeing the cam: Confirms installed centerline matches the cam card; essential for performance and avoiding interference.
• Break-in procedure: Flat-tappet cams need high-zinc oil and 20–30 minutes at 2,000–2,500 rpm; roller cams generally do not require break-in.
• ECU calibration: Idle, fueling, spark, and VVT phasing (if applicable) must be tuned; expect to raise idle speed with aggressive profiles.
• Tools and complexity: DOHC engines require cam locking/setting tools; pushrod V8s are simpler but still demand precision.
• Dyno verification: Confirms AFR, timing, and knock safety; ensures the powerband aligns with gearing and converter.

Professional installation and tuning reduce risks dramatically; cutting corners here is the fastest way to lose power or an engine.

Legal, Warranty, and Cost Considerations

Beyond performance, cam swaps have practical implications owners should account for before turning a wrench.

• Emissions compliance: In many U.S. states, non-exempt cams can fail inspection; look for CARB EO numbers if you need 50-state legality.
• Warranty and insurance: Powertrain warranties can be denied for modified engines; disclose significant mods to your insurer where required.
• Noise and inspection: A choppy idle and louder exhaust can attract attention and may trip local noise limits.
• Cost range: Parts for a typical pushrod V8 cam package (cam, springs, pushrods, gaskets) often run $800–$2,000; labor can be $1,500–$3,000+; tuning adds $400–$1,000.

Budget holistically—valvetrain, tuning, and potential driveline changes—so the project delivers value, not just sound.

Who Should Consider Camming—and Who Shouldn’t

The best candidates have clear performance goals and can accommodate the side effects; others may be better served by milder mods.

• Good candidates: Track-day or drag enthusiasts, experienced modifiers, and owners of older non-VVT V8s seeking substantial NA gains.
• Proceed with caution: Daily drivers needing smooth idle and strong low-end, vehicles in strict emissions regions, or cars still under warranty.
• Alternatives: On modern engines, a quality tune, intake/exhaust, and optimized VVT phasing can deliver safer, street-friendly gains.

If your top priority is reliability and compliance, consider milder profiles or non-invasive upgrades before a cam swap.

Summary

Camming a car changes valve events to re-shape the torque curve and unlock power where you want it, often adding a lopey idle as a byproduct. The payoff can be significant—especially on NA V8s—when the cam, supporting hardware, and tune are matched to your goals. The trade-offs are real: drivability, emissions compliance, cost, and setup complexity. Choose the profile around your use case, prepare the valvetrain and calibration accordingly, and a cam swap can transform both the performance and personality of your engine.