Why Upgrade to a Comp Cams Camshaft in Your Classic Mopar?

If you drive a classic Mopar muscle car—a 1969 Dodge Charger, a 1970 Plymouth 'Cuda, or a Road Runner with a 440 Six Pack—you already understand the satisfaction of raw American horsepower. The camshaft is the heart of an engine’s personality. It controls valve timing, lift, and duration, directly shaping torque curve and peak horsepower. A Comp Cams camshaft is engineered to unlock hidden potential in small-block and big-block Mopar engines, improving throttle response and overall drivability without sacrificing reliability. Whether you are restoring a numbers-matching car or building a weekend street brawler, a properly installed Comp Cams camshaft can transform your driving experience.

This guide walks you through every phase of the installation, from tool selection to the first fire-up, with the kind of detail that ensures a long-lasting, high-performance build.

Tools and Materials You Will Need

Gather everything before you start. A well-organized workspace saves time and prevents mistakes. For a clean install, you will need:

  • Comp Cams camshaft (choose a grind matched to your Mopar engine’s displacement and intended use, e.g., XE274 for street/strip or 21-222-4 for a torquey small-block)
  • Socket set (1/4″ and 3/8″ drive, metric and SAE – classic Mopars use SAE fasteners)
  • Combination wrenches (open-end and box-end, 3/8″ to 3/4″)
  • Torque wrench (that reads in foot-pounds and inch-pounds; a click-type is ideal)
  • Camshaft installation tool (or a long bolt with a large washer to protect the cam snout)
  • High-quality engine oil (for lubricating cam lobes and lifters during break-in)
  • Comp Cams break-in additive (zinc and phosphorus compounds essential for flat-tappet cams)
  • Complete gasket set (valve cover gaskets, timing cover gasket, oil pan gasket if disturbing the pan)
  • Timing chain and gears (always replace when installing a new camshaft; a double-roller set is recommended)
  • Shop manual for your specific Mopar model (Chrysler Service Manual or a high-quality aftermarket book)
  • Dial indicator and stand (for checking cam timing and piston-to-valve clearance)
  • Feeler gauges
  • Engine stand or hoist (optional but highly recommended for accessible work)

Preparation Steps: Setting Up for Success

Classic Mopar engine bays are tight. Taking the time to properly prepare prevents frustration and damage. Follow these steps methodically.

Disconnect and Drain

  • Disconnect the negative battery cable to avoid accidental shorts or starter engagement.
  • Remove the air cleaner assembly, carburetor (or throttle body), and any brackets that block access to the front of the engine.
  • Drain the engine oil into a suitable container. Replace the oil filter.
  • Drain the coolant from the radiator and engine block. Open both petcocks to avoid a mess later.

Remove the Valve Covers and Timing Cover

On most small-block (LA) and big-block (B/RB) Mopars, the valve covers are held by a series of bolts. A 3/8″ socket works. Carefully pry them loose if the gasket is stuck—use a plastic trim tool to avoid damaging the aluminum or stamped steel covers. Remove the rocker arms and pushrods. Label them so they can return to their original positions if reusing the existing lifters (not recommended with a new cam).

Unbolt the timing cover. The harmonic balancer will need to be removed with a puller. A standard three-jaw puller works, but a dedicated Mopar balancer puller is safer. If the balancer is rusted on, apply penetrating oil and let it soak. Once off, the timing cover gasket can be scraped clean.

Removing the Old Camshaft

With the timing chain exposed, you can now access the camshaft. This is the point where many DIYers rush. Patience here prevents costly errors.

Timing Chain and Gear Removal

  • Rotate the engine to top dead center (TDC) on cylinder #1. The timing marks on the crank and cam gears should align. Mark the distributor rotor position if you plan to reinstall the same distributor.
  • Remove the timing chain tensioner (if equipped), then unbolt the cam gear. Slide the chain and gear off the crankshaft gear together.
  • Remove the camshaft retainer plate (usually two bolts). On some big-blocks, you may also need to remove the thrust plate.

Slide Out the Old Camshaft

Gently pull the camshaft straight out of the block. Watch for the cam bearings and do not scratch them. If the cam is stuck, use a slide hammer cam puller. Lay the old cam on a bench and inspect the lobes. Uneven wear or a wiped lobe signals problems with lifter geometry or oil delivery—address those before installing the new cam.

Installing the New Comp Cams Camshaft

This is where preparation meets precision. Every step here is critical to ensure the cam properly operates for thousands of miles.

Lubrication Is King

Apply a generous coating of engine oil to the new camshaft bearing journals. Then coat each lobe with Comp Cams extreme-pressure break-in lube or an equivalent high-zinc assembly lube. Do not skip this. The first few minutes of operation are the most demanding on a flat-tappet cam.

Insert the New Cam

  • Carefully slide the camshaft into the engine block, aligning the gear drive pin. Rotate it gently as you push it home so the bearings engage smoothly.
  • Install the camshaft retainer plate and torque the bolts to the factory specification (for a Mopar LA small-block, typically 35–45 ft-lbs, but confirm with your shop manual).

Install the New Timing Set

This is the most common place to induce an error. Use a quality double-roller timing chain and matching gears. Line up the timing marks exactly as the engine is at TDC on the compression stroke (crank keyway at 12 o’clock, cam gear mark aligned with the mark on the crank gear). Many Comp Cams camshafts come with an advance/retard keyway—use the straight-up (0°) setting for initial installation unless your cam card specifies otherwise.

Torque the cam gear bolts to 35–45 ft-lbs (or as specified on the gear manufacturer’s instructions). For big-block Mopars, the cam gear bolt is often 5/16″ and torques to 25–30 ft-lbs. Apply threadlocker to the cam bolt threads.

Check Camshaft End Play

With the retainer plate installed, move the cam forward and backward. End play should be between 0.001″ and 0.005″. If it’s too tight, the thrust surface may need clearance. Too loose indicates a worn retainer or thrust button.

Reassembly: Putting the Engine Back Together

Now install new gaskets and reattach timing cover, oil pan if removed, and valve train.

Install New Lifters and Pushrods

Always use new lifters with a new cam. Old lifters have a worn wear pattern that will quickly eat a new cam lobe. Apply the break-in lube to the bottom of each lifter. Drop them into their bores. For flat-tappet cams, use the correct lifter type (mechanical or hydraulic). Install pushrods—make sure they are the correct length for your valvetrain geometry.

Reinstall Rocker Arms

For hydraulic cams, adjust preload. For solid cams, set lash to the spec on the cam card. A rule of thumb for many Mopar hydraulic cams is 1/4 to 1/2 turn past zero lash. Use a feeler gauge for solid lifters.

Valve Covers, Timing Cover, Fluids

  • Install new gaskets on the valve covers and timing cover. Use a thin layer of gasket sealer at the corners of the timing cover to prevent oil leaks.
  • Reattach the harmonic balancer. Use a Mopar-specific installation tool to avoid hammering it on. Torque the main bolt to 135 ft-lbs (small-block) or 150 ft-lbs (big-block).
  • Replace the engine oil with a conventional 10W-30 or 10W-40 containing a high level of zinc (ZDDP). Add a bottle of break-in additive.
  • Fill the coolant system with a 50/50 mix of antifreeze and distilled water.

First Start and Break-In Procedure

The break-in process is not optional. It determines whether your camshaft will last or fail within minutes.

Before You Turn the Key

  • Prime the oil system. Remove the distributor and use a primer shaft with a drill to pressurize the oil galleries. Turn the drill until you see oil reaching the rocker arms.
  • Check all fluid levels: oil, coolant, power steering, transmission fluid if applicable.
  • Remove the spark plugs to relieve compression during initial rotation. Crank the engine until oil pressure registers on the gauge (or light goes out).

Fire It Up

Reinstall spark plugs. Start the engine and immediately bring the RPM to 2,000–2,500. Do not let it idle. Idle rpm is too low to properly splash oil onto the cam lobes, and the break-in additive needs high oil volume. Run the engine at varying RPM between 2,000 and 3,000 for the first 20 minutes. Watch for oil pressure, coolant temperature, and any abnormal noises. If you hear tapping from a lifter, don’t panic—it may bleed down as oil circulates, but if it persists, shut down and check lash.

After 20 minutes, reduce RPM to a normal idle and inspect for leaks. Let the engine cool, then recheck valve lash (if solid) and retorque the intake manifold bolts.

Final Checks and Tuning

Take the car for a gentle drive. Vary engine speed, but avoid sustained full-throttle pulls until you have at least 500 miles on the cam. After the break-in, change the oil and filter again. This removes any metal particles shed during break-in.

Consider adding a Comp Cams adjustable timing chain to fine-tune power delivery. Degreeing the cam using a dial indicator ensures the camshaft is installed exactly at the specified intake centerline. This step is crucial for maximizing power and preventing piston-to-valve interference, especially with high-lift cams. Refer to Comp Cams’ official degreeing guide for detailed instructions.

For tuning, adjust your carburetor or EFI system to match the cam’s vacuum characteristics. A cam with more duration may require a higher idle speed and different timing curve. A 10–12° initial timing with 34–36° total timing is a good starting point for most street Mopars. Check Mopar’s timing recommendation page for additional reference.

Common Pitfalls and How to Avoid Them

  • Wiped lobes – almost always caused by insufficient break-in or poor oil. Follow the break-in procedure exactly, and use oil with at least 1,200 ppm zinc.
  • Cam timing chain slip – always use a new, high-quality timing set. A stretched chain can cause interference and poor performance.
  • Incorrect lifter preload – too tight and valves hang open; too loose and engine is noisy and loses power. Use a pushrod length checker if unsure.
  • Forgetting to prime the oil system – a dry start destroys a cam in seconds. Spend the time to prime.

Best Practices for Long-Term Reliability

After installation, maintain a strict oil change schedule with high-zinc oil. Consider a Comp Cams roller rocker arm setup for even greater valvetrain stability. For high-RPM applications, upgrade to a Comp Cams double valve spring kit to prevent valve float.

Finally, always keep a shop manual handy. Classic Mopars have specific quirks—for example, the small-block LA series uses a chain-driven cam while the big-block uses a gear-driven or chain. Knowing the difference avoids ordering the wrong timing set. For parts and specifications, the Allpar Cam Installation Guide is a trustworthy resource.

Conclusion

Installing a Comp Cams camshaft in your classic Mopar muscle car is one of the most effective ways to wake up a stock engine. Whether you are aiming for a lopey idle at a car show or that extra punch at the drag strip, careful installation and break-in are the keys to success. Take your time, use the right tools, and respect the engine. Your Mopar will reward you with a lifetime of thrilling performance.