Selecting the right camshaft is one of the most impactful decisions you can make when building or upgrading an engine. The camshaft dictates valve timing, lift, and duration—directly controlling how the engine breathes at different RPM ranges. Comp Cams is a leading manufacturer known for a wide array of cam profiles, but even the best components can cause headaches if mismatched, improperly installed, or poorly tuned. This guide covers the fundamentals of camshaft function, dives deep into common problems with Comp Cams and their solutions, and provides actionable advice to help you pick the perfect cam for your build.

Understanding Camshaft Basics

A camshaft's job is to open and close the intake and exhaust valves at precise moments in the engine cycle. The shape of each lobe determines four key parameters:

  • Lift – How far the valve opens. More lift increases airflow potential but stresses valvetrain components.
  • Duration – How long the valve stays open, measured in crankshaft degrees at a given lift (usually 0.050 inch). Longer duration shifts the power band higher.
  • Lobe Separation Angle (LSA) – The angle between the centerlines of the intake and exhaust lobes. A tighter LSA (e.g., 108°) increases overlap for a choppy idle and top-end power; a wider LSA (e.g., 114°) smooths idle and broadens torque.
  • Lobe Profile – The rate at which the lobe opens and closes the valve. Advanced profiles (like those using roller lifters) can open valves faster without excessive friction.

These four elements interact with your engine's displacement, cylinder head flow, compression ratio, and intended use. Choosing a cam without considering these factors is the root of many problems. For detailed specs on aftermarket profiles, visit the Comp Cams official website.

Common Problems with Comp Cams and How to Fix Them

Even a high-quality Comp Cam can produce disappointing results if one of these five common issues arises. Below we break down each problem with its root causes, symptoms, and step-by-step solutions.

1. Incorrect Valve Timing

Valve timing refers to when the intake and exhaust valves open and close relative to piston position. A cam that is installed "straight up" (aligned with the crankshaft keyway) may still be off by several degrees due to manufacturing tolerances, offset keys, or timing set variability. Symptoms include a rough idle, loss of low-end torque, or a power band that feels "off" from the cam card specs.

Solution: Always degree the cam using a degree wheel and dial indicator before final assembly. Attach the degree wheel to the crankshaft, set the piston at top dead center (TDC), and measure the intake lobe centerline. Adjust the cam timing using an offset crank key or adjustable timing set until the centerline matches the cam card. For help interpreting degreeing results, refer to Summit Racing’s guide on degreeing a camshaft.

2. Excessive Wear on Cam Lobes

Flat-tappet camshafts rely on a zinc-based anti-wear additive (ZDDP) in the oil. Modern low-zinc oils can cause lobe and lifter scuffing within minutes of startup. Roller cams are less prone, but still require proper break-in oil and valve spring pressures that are not too high. Symptoms: a ticking noise from the valvetrain, metal glitter in the oil, or visible lobe pitting upon removal.

Solution: For flat-tappet Comp Cams, use a break-in oil containing at least 1,200 ppm of ZDDP. Follow the break-in procedure exactly: run the engine at 2,000–2,500 rpm for 20 minutes, varying the speed slightly. Avoid idling during break-in. For roller cams, use a conventional oil with high zinc content for the first 500 miles. After break-in, regularly change the oil and filter. If wear is already present, replace the cam, lifters, and pushrods—never reuse worn lifters on a new cam.

3. Poor Engine Performance After Installation

You install a new Comp Cam, but the car feels sluggish, lacks top-end power, or detonates under load. This is rarely the cam's fault. More often, the engine’s fuel and ignition timing are not optimized for the new curve. A cam with longer duration moves the power band up, so a carburetor calibrated for a stock cam will be too rich or too lean off idle. Similarly, the distributor’s mechanical advance may not match the cam’s LSA.

Solution: Re-tune the engine for the new cam. Adjust the fuel mixture using air-fuel ratio gauges (target 12.5–13.0:1 at wide-open throttle). Recurve the distributor to provide total advance (typically 32–36° at peak torque) while adjusting the vacuum advance for street driving. If the cam is a big stick (duration > 270° at 0.050”), consider upgrading the carburetor or throttle body to increase airflow. Comp Cams' tech section offers tuning guidelines for their specific grinds.

4. Inadequate Clearance Leading to Valve-to-Piston Contact

High-lift cams push valves deeper into the cylinder. If the piston has insufficient valve relief depth, or if the cam timing is advanced, the valves can strike the pistons. This causes bent valves, broken guides, and catastrophic engine failure. Symptoms: a loud metallic clatter on startup, loss of compression, or zero valve lash after running.

Solution: Measure valve-to-piston clearance during assembly using clay. Place a small ball of clay on the piston crown, install the head (with gasket), and rotate the engine through full cycle. Remove the head and measure the clay thickness. Minimum safe clearance is 0.080 inch for intake and 0.100 inch for exhaust (tighter allowed with aluminum rods/pistons due to less expansion). If clearance is insufficient, fly-cut deeper valve reliefs, install a smaller base circle cam, or retard the cam timing. Always check for both intake and exhaust clearance at the piston's TDC and at 10° before/after TDC.

5. Improper Installation Leading to Multiple Issues

Incorrectly installed cam position, loose timing chain, or mismatched lifter preload can cause a host of problems: bent pushrods, erratic timing, and premature failure. Many DIY builders skip the step of checking the cam’s end-play or fail to align the dot marks correctly. A chain that is too loose will jump teeth under load.

Solution: Follow the manufacturer’s installation instructions precisely. Use a torque wrench on cam sprocket bolts and timing cover bolts. Set cam end-play to 0.002–0.005 inch using a thrust plate. Ensure the cam gear dot aligns with the crank gear dot (both gears are typically marked with a “0” or arrow). For hydraulic lifters, set preload by adjusting the rocker arm: turn the pushrod until zero lash, then tighten 1/2 to 1 full turn (depending on lifter type). For solid lifters, set lash using a feeler gauge to the specified cold clearance. After assembly, rotate the engine by hand at least two full revolutions to confirm no binding.

Choosing the Right Comp Cam

With the problems addressed, focus on selecting a cam that suits your engine’s specific requirements. Comp Cams offers hundreds of grinds; the wrong choice can make a hot street car undrivable or a race car too peaky.

Match Cam to Application

  • Mild Street / Daily Driver: Duration 210–230° at 0.050”, LSA 112–114°, lift 0.450–0.500 inch. Produces strong torque from 1,500–5,000 rpm, smooth idle.
  • Street/Strip Performance: Duration 230–250°, LSA 110–112°, lift 0.500–0.550 inch. Good power from 2,500–6,500 rpm, noticeable lope. Requires converter stalls around 2,800–3,200 rpm and headers.
  • Racing / High RPM: Duration 260–290°+, LSA 106–110°, lift 0.600 inch+. Peak power above 6,000 rpm. Needs ported heads, solid roller lifters, and high compression.
  • Forced Induction: Duration similar to mild street but with wider LSA (114–116°) to reduce overlap and prevent boost bleed-off. Lift should be moderate to avoid cylinder pressure issues.

Consider Supporting Modifications

A cam is only as good as the parts around it. For the cam to shine, match it with:

  • Flow-matched cylinder heads (increase valve size if cam lift exceeds stock springs)
  • Valve springs rated for the cam’s max lift (check coil bind clearance)
  • Pushrods of correct length to achieve ideal rocker arm geometry
  • A fuel delivery system capable of supplying the needed mixture at peak RPM
  • A correctly calibrated distributor or engine computer

Break-In and Installation Best Practices

After selecting the cam, proper break-in is non-negotiable. Use a pre-lube (comp cams includes a lubricant) on all lobes and lifter bases. Set initial ignition timing to 10–12° BTDC. Prime the oil system until oil reaches the rocker arms. Start the engine and immediately raise RPM to 2,000–2,500 rpm. Hold that range for 20 minutes, avoiding idling. After break-in, check valve lash (if solid), adjust rockers on hydraulic cams after the lifters bleed down, and re-torque the intake manifold after the first heat cycle. Change oil and filter after the first 30 minutes of run time and again after 500 miles.

Conclusion

Comp Cams offers a reliable foundation for engine builds, but success depends on understanding camshaft dynamics, avoiding common pitfalls, and matching the profile to your specific application. By degreeing the cam, using proper lubrication and break-in procedures, and verifying clearances, you can sidestep the most frequent problems. Remember that a camshaft does not work in isolation—tuning the fuel, ignition, and valvetrain components is equally critical. Armed with the insights in this guide, you can confidently select a Comp Cam that unlocks your engine’s true potential without the frustration of post-installation issues.