Introduction: Unleashing the Full Potential of Your E‑Body Challenger

Installing a Mopar Stage III camshaft in your E‑body Challenger is one of the most effective ways to unlock serious horsepower and torque. Designed for high‑performance street and strip applications, the Stage III cam delivers a aggressive idle, strong mid‑range pull, and a top‑end rush that transforms the driving experience. Whether you’re running a 340 or a 383, this upgrade will push your engine well past the 400‑horsepower mark when paired with proper supporting modifications.

This step‑by‑step guide goes far beyond the basic instructions. We’ll cover every tool you’ll need, critical preparation steps, detailed removal and installation procedures, reassembly tips, and the final break‑in process. We’ve also included expert insights on common pitfalls, performance expectations, and tuning requirements. By the end, you’ll have the confidence to tackle this project in your own garage and enjoy the reward of a perfectly dialed‑in Mopar muscle car.

Tools and Materials Needed

Having the right tools on hand makes the job safer and faster. Do not try to shortcut with generic substitutes; the Stage III cam requires precise installation. Below is a comprehensive list of what you need.

Essential Tools

  • Complete 3/8‑inch and 1/2‑inch drive socket set (metric and SAE) with extensions
  • Torque wrench (ft‑lb and in‑lb ranges)
  • Harmonic balancer puller and installer
  • Camshaft installation tool (or a long bolt and washers to safely guide the cam in)
  • Dial indicator with magnetic base
  • Degree wheel (for verifying cam timing)
  • Feeler gauge set
  • Timing light (for final ignition setup)
  • RTV silicone gasket maker and sealant
  • Shop towels, brake cleaner, and degreaser
  • Safety glasses and nitrile gloves

Parts and Supplies

  • Mopar Stage III camshaft (typically P4452793 or equivalent)
  • New lifters (required for flat‑tappet cams; never reuse old lifters)
  • Timing chain set (double‑roller recommended for strength)
  • Timing cover gasket set
  • Valve cover gaskets
  • Intake manifold gasket set
  • High‑zinc break‑in oil (e.g., driven break‑in oil)
  • Assembly lube (molybdenum disulfide paste for the cam lobes and lifter faces)
  • Fresh engine oil and filter
  • Antifreeze/coolant (if draining the cooling system)

Pro tip: Visit Summit Racing or JEGS for package deals on cam and lifter kits, timing sets, and gaskets tailored to your engine family.

Preparation Steps

Rushing the prep work leads to mistakes. Take your time to create a clean, organized workspace and to properly prepare the engine.

Vehicle and Engine Prep

  • Park your Challenger on a level concrete floor and set the parking brake. Use wheel chocks for safety.
  • Disconnect the negative battery cable. This prevents accidental starter engagement and protects the alternator.
  • Drain the engine coolant (if the radiator hoses will be disturbed) and remove the radiator and fan shroud for better access. A cross‑flow radiator in an E‑body can be tight; consider using a Champion Cooling radiator if you plan future upgrades.
  • Remove the air cleaner assembly, carburetor (if present), and the intake manifold. Label all vacuum lines and linkage rods.
  • Remove the valve covers and rocker arms. Keep the pushrods in order so they can be reinstalled in the same position if they are still good.
  • Clean the engine valley and the front of the block with brake cleaner and a stiff brush. Any dirt or old gasket material that falls into the oil pan can destroy the new cam bearings.

Setting Up for Cam Change

  • Rotate the crankshaft so that the #1 cylinder is at top dead center (TDC) on the compression stroke. Use a piston stop tool or simply watch the distributor rotor position.
  • Remove the harmonic balancer with a puller. Never hammer on the balancer; it can damage the rubber isolator.
  • Remove the timing cover, timing chain, and camshaft gear. Note the position of the timing marks for reference.

Removing the Old Camshaft

Once the timing set is out, you can pull the old cam. This step requires patience—a bent cam can ruin the block.

Step‑by‑Step Removal

  1. Remove the fuel pump and distributor (if they haven’t been taken off yet). The cam gear drives the distributor; the cam must come out without interference from the drive gear.
  2. Remove the camshaft retaining plate (if equipped). Most small‑block Mopars have a cam button and a thrust plate. Unbolt and set aside.
  3. Use the cam installation tool (a long bolt with large washers works) to gently pull the cam toward you. Rotate the cam as you pull to avoid binding on the bearings. If it sticks, stop and check for a burr on the cam gear or a misaligned lifter. Do not force it.
  4. Inspect the old cam for lobe wear, scoring, or pitting. Even if it looks fine, the symmetrical lobes of a stock cam are no match for the aggressive Stage III profile. Dispose of the old cam and lifters responsibly.

Important: If you are upgrading from a hydraulic flat‑tappet cam, you must replace the lifters. The old lifters have worn a mating pattern with the old cam that will not transfer to the new one. Use a Lunati or Mopar Performance lifter set.

Installing the Mopar Stage III Cam

Now for the heart of the upgrade. Follow these steps meticulously to ensure long life and maximum performance.

Pre‑lubrication Is Critical

Mopar Stage III cams are typically flat‑tappet (hydraulic or mechanical). The lobes require a generous coating of assembly lube. Apply the moly paste to every lobe and the lifter faces. Also coat the distributor drive gear and the cam bearing journals with engine oil.

Installation Procedure

  1. Slide the new cam into the block using the installation tool. Rotate it slowly as you push, keeping the cam parallel to the bore. Once it seats fully, install the cam retaining plate and button. Torque to factory specs (typically 200 in‑lb for the thrust plate bolts).
  2. Install new lifters into their bores. Use assembly lube under the lifter and on the roller (if using hydraulic roller lifters). For flat‑tappet, ensure each lifter can rotate freely in its bore.
  3. Degree the camshaft (optional but highly recommended). Use a dial indicator on the #1 intake lifter to verify the lobe centerline matches the card that came with your cam. If off, adjust with offset bushings or an adjustable timing set. A detailed degreeing guide is available at MotorTrend.
  4. Install the double‑roller timing chain and gear set. Align the timing marks so that the cam gear is advanced or retarded per the cam card (usually straight up). Torque the cam gear bolt to 50–60 ft‑lb with thread locker.
  5. Check piston‑to‑valve clearance (especially if you have aftermarket pistons). Turn the engine over by hand with the spark plugs removed. Listen for interference. A small margin of error is okay; 0.080‑inch intake and 0.100‑inch exhaust are safe minimums.

Reassembly

With the new cam and timing set in place, it’s time to put the engine back together. Pay attention to sealing and torque specs.

Front Cover and Accessories

  • Install a new timing cover gasket and front seal. Use a dab of RTV in the corners where the gasket meets the oil pan.
  • Install the harmonic balancer using the correct installer tool. Tighten the balancer bolt to high torque (typically 135 ft‑lb) – do not under‑torque.
  • Reinstall the water pump, alternator brackets, and any emission components you removed earlier. If you plan to upgrade to an electric fan, now is a good time.

Valvetrain Reassembly

  • With the lifters in place, install the pushrods. Check pushrod length if you changed cylinder heads or valve train components; the Stage III cam may require a longer or shorter pushrod for correct rocker geometry.
  • Install the rocker arms and adjust valve lash according to the cam spec. For a hydraulic flat‑tappet, you’ll need to set the preload (usually 0.020‑0.040 inch). For a solid cam, set the lash with feeler gauges while the engine is hot.
  • Torque the rocker shaft bolts in stages to 25 ft‑lb (small‑block) or 35 ft‑lb (big‑block). Use a criss‑cross pattern.

Intake and Valve Covers

  • Apply a thin bead of RTV around the intake manifold ports and install a new gasket. Torque the intake bolts in three passes to the Mopar spec (usually 35–40 ft‑lb for the center bolts, 25–30 ft‑lb for the ends).
  • Install new valve cover gaskets. Use a lightweight coat of sealant on the gasket side that contacts the head – do not overdo it, as excess can squeeze out and reach the oil pan.

Final Checks and Start‑Up

Before you crank the engine, go through this checklist. A mistake here can be costly.

Pre‑Start Verification

  • Reconnect the battery, spark plug wires, distributor cap, and all vacuum lines. Set the ignition timing to 10° BTDC (or the cam card recommendation).
  • Fill the engine with high‑zinc break‑in oil. Do not use synthetic oil for the first 500 miles.
  • Install a new oil filter.
  • Prime the oil system: Use a priming tool on the distributor shaft to spin the oil pump until you see oil at all the rocker arms. This is critical for the new cam and lifters.
  • Fill the cooling system with the correct mixture of coolant and distilled water.
  • Double‑check that all bolts are tight, especially the harmonic balancer bolt and cam gear bolt.

Break‑In Procedure

  1. Start the engine and immediately raise the RPM to 2000–2500. Do not let it idle – a flat‑tappet cam requires steady load to break in the lobes. Keep the RPM above 2000 for the first 20 minutes.
  2. Watch the oil pressure gauge. It should be at least 40 psi at 2000 RPM.
  3. Listen for any ticking or knocking. A slight tick is normal for solid lifters; a loud knock indicates valve train interference.
  4. After 20 minutes, shut the engine off and let it cool. Retorque the cylinder head bolts (if needed) and recheck valve lash.
  5. Change the oil and filter after the first half‑hour of running. This removes any assembly debris and metal particles from the break‑in.

Performance Expectations and Tuning Tips

Once the cam is broken in, you’ll notice a major change in power delivery. The Mopar Stage III cam typically has 280–290 degrees duration and 0.500–0.530 inch lift. Expect a strong idle lope, a peak torque around 3500 RPM, and horsepower peaking at 6200 RPM with the right intake and headers.

Supporting Mods to Get the Most Out of It

  • Carburetor: Upgrade to a 750‑850 CFM Holley or Edelbrock for the Stage III cam. The stock 650 CFM will be restrictive.
  • Ignition: A high‑output electronic ignition (MSD or Mopar Performance) is a must. The aggressive cam can blow out the spark at high RPM.
  • Exhaust: Long‑tube headers and a 2.5‑inch or 3‑inch exhaust system help the engine breathe. Check out TTI headers for E‑body fitment.
  • Torque converter: For automatic transmissions, a 3000‑3500 RPM stall converter will put the engine in its power band.

If you experience low vacuum at idle (below 10 inches), you may need to adjust the carburetor’s idle circuit or install a vacuum reservoir for power brakes. The Stage III cam is not for daily driving, but it turns your Challenger into a fire‑breathing street machine.

Common Pitfalls and How to Avoid Them

  • Using old lifters: Always replace lifters with a new cam. Flat‑tappet lifters must be matched to the cam – they are not interchangeable.
  • Insufficient assembly lube: A dry start can wipe a cam lobe in seconds. Apply lube liberally.
  • Ignoring degreeing: Even Mopar factory cam cards can be off. Degreeing ensures the cam timing matches the intended curve.
  • Skipping the break‑in: The first 20 minutes are the most critical. Do not take shortcuts – your engine’s life depends on it.

Conclusion

Installing a Mopar Stage III cam on your E‑body Challenger is one of the most satisfying performance upgrades you can make. The sound and feel of a big cammed small‑block are unmistakable. With careful preparation, the right tools, and attention to detail, you can complete this project in a weekend and enjoy a genuinely fast, street‑oriented muscle car. Remember to check your local emissions laws if you drive the car on public roads, and always wear safety gear.

For further reading, the For A Bodies Only Mopar Forum and HemiChallenger.com are excellent resources for E‑body owners sharing cam swap experiences.