Why Upgrade to a Comp Cams Camshaft?

Swapping in a Comp Cams camshaft is one of the most effective ways to unlock the hidden power in a classic Chevy small-block or big-block. The camshaft controls valve timing, lift, and duration, directly influencing horsepower, torque, and throttle response. Whether you're building a street cruiser, a weekend bracket racer, or a high-performance show car, choosing the right Comp Cams grind can shift your engine’s power band exactly where you need it. This guide provides a comprehensive, engine-building approach to installing your new cam with confidence. You’ll learn not only the mechanical steps but also the crucial break-in and tuning procedures that separate a successful build from a costly mistake.

Tools and Materials Needed

Before pulling wrenches, gather everything you’ll need. Having the right tools on hand prevents interruptions and ensures precision work. Below is a complete list with important notes on why each item matters.

  • Comp Cams camshaft – Verify the part number matches your engine’s application (e.g., classic Chevy small/big block, flat tappet or roller).
  • Socket set and extensions – SAE sizes for Chevy engines; include a 1/2-inch drive for main bolts, 3/8-inch for accessories.
  • Torque wrench – essential for cam bolts, timing cover, and head bolts; use one that reads in lb-ft and lb-in for smaller fasteners.
  • Engine oil – high-zinc break-in oil (not modern low-zinc) to protect the flat-tappet lobes. For roller cams, use a quality 10W-30 or 10W-40.
  • Camshaft assembly grease – moly-based grease specifically for cam lobes and distributor gear (Comp Cams 188 or equivalent).
  • Timing chain set – double-roller recommended for strength; includes cam and crank sprockets with timing marks.
  • Camshaft installation tool (optional) – a long bolt or dedicated handle that screws into the cam’s front to guide it in without marring bearings.
  • Gasket set – timing cover gasket, intake manifold gasket, valve cover gaskets, and oil pan gasket if removed.
  • Rags and cleaning supplies – brake cleaner, shop towels, and a magnet for dropped fasteners.
  • Pushrod length checker (if replacing lifters) – needed to verify geometry with new cam.
  • Valve springs (often required) – Comp Cams recommends springs matched to the cam’s lift; inspect for coil bind at max lift.

For a smooth installation, consider purchasing a complete timing set, a new harmonic balancer bolt, and a quality oil pump priming tool.

Preparation Steps

Proper preparation saves time and prevents damage. Work in a well-ventilated area with the vehicle on jack stands or a lift. Ensure the engine is cool before starting.

Disconnect the Battery and Drain Fluids

Always disconnect the negative battery cable to eliminate accidental starter engagement. Drain the engine oil into a container; if the oil pan must be removed, drain coolant from the block as well. Remove the radiator hoses and fan shroud for access.

Remove Obstructions

Remove the air cleaner, carburetor or throttle body, distributor cap, and intake manifold. With the manifold off, stuff a clean rag into the lifter valley to prevent debris from falling into the oil pan. Remove the valve covers, rocker arms, and pushrods, keeping them in order if reused (though many upgrades call for new pushrods).

Access the Timing Chain and Camshaft

Remove the harmonic balancer or damper using a puller (do not pry). Unbolt the timing chain cover and carefully slide it off. Remove the timing chain and sprockets, noting the cam sprocket’s orientation. Now the old camshaft is exposed.

Removing the Old Camshaft

Removing the old cam requires patience to avoid damaging the cam bearings. Follow these steps carefully.

  • Remove the distributor (mark its rotor position for reinstallation) and the oil pump drive gear.
  • Loosen and remove the camshaft retaining plate or thrust button bolts.
  • Rotate the engine to a position where the cam lobes have clearance to slide past the connecting rods. For most Chevy V8s, TDC on #1 cylinder works well.
  • Carefully slide the old camshaft out of the block toward the front. If it binds, rotate the crank slightly to move rods out of the way. Never force the cam – you can damage the rear cam bearing or block the bore.
  • Inspect the old cam lobes and journals for wear patterns; excessive wear may indicate oiling issues. Remove any timing chain debris from the oil pan pick-up screen if possible.

Installing the Comp Cams Camshaft

Now for the heart of the build. A successful cam install depends on lubrication and precise alignment.

Lubricate the New Cam

Apply a generous coat of moly assembly grease to each cam lobe and journal. Also grease the distributor drive gear if the cam has one. This grease provides initial lubrication during the critical first seconds of start-up.

Slide It In

Using a cam installation tool or a long bolt threaded into the cam’s front hole, gently guide the new Comp Cams camshaft into the block. Rotate it slowly while pushing to allow lobes to pass the connecting rods. Once the cam is fully seated and the thrust plate is aligned, install the retaining bolts to Comp Cams’ torque specification (usually 20-25 lb-ft).

Time the Camshaft

Install the timing chain set with the cam sprocket aligned to the crank sprocket dot-to-dot at top dead center (TDC). For a typical Chevrolet V8, both dots should be aligned when #1 cylinder is at TDC on the compression stroke. Rotate the engine two full turns to verify alignment marks return. Install the timing chain cover with a new gasket and a dab of RTV at the oil pan corners.

Reinstall the Harmonic Balancer

Clean the balancer bore and crank snout. Apply a thin coat of oil to the seal surface and draw the balancer on with the installation bolt (never hammer it). Torque the balancer bolt to the factory specification (typically 70 ft-lb or more for small blocks).

Reassembling the Engine

With the cam in place, reassemble the valvetrain and engine. Use new gaskets and torque hardware in sequence.

  • Lifters and pushrods: If using new lifters, soak them in break-in oil for 20 minutes. Install each lifter in its original bore or new location per manufacturer instructions. Adjust the rocker arms to zero lash (turn the pushrod until resistance) plus a half turn for hydraulic cams, or follow specific lash settings for solid cams.
  • Valve covers and intake: Apply gasket sealer to the valve covers and intake manifold ends. Torque intake bolts in a cross pattern to spec (usually 25-30 ft-lb).
  • Oil pan: If removed, install a new gasket and torque oil pan bolts to 10-12 ft-lb. Fill the engine with break-in oil (high zinc) and a new filter.
  • Distributor: Reinstall the distributor with the rotor pointing to the plug wire terminal for #1 cylinder. Adjust initial timing after start-up.

Final Checks and Break-In Procedure

The break-in process is the most critical part of a camshaft installation, especially for flat-tappet cams. Follow these steps exactly.

  • Prime the oil system: Use a priming tool in the distributor hole to spin the oil pump with a drill until oil reaches the rocker arms. This prevents dry starts.
  • Check ignition timing: Set initial timing to the cam card’s recommendation (often 10-16 degrees BTDC). Ensure timing advance is working.
  • Start-up: Start the engine and immediately bring the RPM to 2000–2500. Do not let it idle. The high RPM ensures oil splash to the cam lobes. Listen for any valve train noise; if present, shut off and adjust.
  • Break-in duration: Keep the engine above 2000 RPM for 20 minutes, varying the speed gently but never to idle. This wears the cam lobes and lifters together. After break-in, change the oil and filter to remove metal particles, then refill with quality high-zinc oil (or conventional 10W-40 with a zinc additive).

Important: Improper break-in (low RPM or excessive idling) can wipe a flat-tappet cam in minutes. For roller cams, follow Comp Cams’ instructions; break-in is less critical but still beneficial.

Tuning and Optimization

A new camshaft changes the engine’s airflow, requiring adjustments to the ignition and fuel systems.

Adjust Ignition Timing

Use a timing light to set initial timing per the cam card. Check total timing (initial plus mechanical) at 3000–3500 RPM; many Chevy small blocks run best at 34–38 degrees total. Adjust the distributor’s mechanical advance springs to bring advance in at the right RPM. Consider the use of a dial-back timing light for accuracy.

Carburetor or EFI Tuning

A larger cam often increases overlap, which pulls more fuel through at idle. Re-jet the carburetor to lean or richen the mixture as needed. Check the vacuum reading; a low vacuum may require a stall converter for automatic transmissions. Modern EFI systems may need a recalibration using a wideband O2 sensor.

Valve Lash Adjustments

For solid camshafts, hot lash adjustment after break-in is essential. Let the engine cool to 140°F, then set each rocker to the recommended clearance (e.g., .020 inch intake, .022 inch exhaust common on Comp Cams). For hydraulic cams, a zero-lash + 3/4 turn preload works well with most lifters.

Dyno Tuning

For maximum power, a session on a chassis dynamometer allows precise tuning of air-fuel ratio and timing. Many racers see gains of 20+ horsepower by dialing in the tune with the new cam. Comp Cams’ website offers cam card data that provides a baseline.

Common Mistakes to Avoid

Even experienced builders can slip. Here are the most frequent pitfalls when installing a cam in a classic Chevy.

  • Using low-zinc oil during break-in: Modern API oils deplete zinc for catalytic converters, leading to lobe wear. Always use break-in oil or additive.
  • Roller cam without proper spring upgrade: High-lift cams can cause coil bind or retainer-to-seal contact. Check compressed height at full lift.
  • Ignoring cam timing: A retarded or advanced cam moves the power band; use the crank/cam sprocket keyways to fine-tune if multiple positions exist.
  • Over-torquing bolts: Cam retainer plate or timing cover bolts can strip in aluminum blocks. Use a torque wrench.
  • Skipping the break-in run: An emotional start-and-rev without sustained high RPM will glaze lobes. Commit to the 20-minute break-in.

For more detailed tech articles, Hot Rod Magazine and Summit Racing’s blog offer valuable resources on camshaft installation and tuning.

Conclusion

Installing a Comp Cams camshaft in your classic Chevy is a rewarding project that transforms the car’s personality. By following this expanded guide – from tools and preparation through careful installation, critical break-in, and precise tuning – you ensure that the cam delivers reliable performance and longevity. Whether you’re chasing a bumpy idle at the stoplight or extracting every horsepower on the track, the time spent on each detail pays off. Now go fire up that Chevy and enjoy the sound of a properly cammed V8.