Introduction to the B‑Body Mopar Camshaft Swap

The B‑body platform from Mopar – encompassing iconic models like the Chrysler 300, Dodge Charger, Plymouth Fury, and their performance variants – has long been a favorite among enthusiasts who crave classic American muscle. Swapping the factory camshaft for a performance grind is one of the most effective single modifications you can make. It changes the engine’s breathing characteristics, shifting the power band to deliver stronger mid‑range and top‑end output, often with a more aggressive exhaust note. This guide will walk you through the complete process: from understanding camshaft fundamentals and choosing the right stick, to preparing your workspace, executing a clean swap, and tuning for reliable gains. Whether you’re working with a 318, 340, 360, or the legendary 440 big‑block, the principles remain the same. Expect to see increases of 20–50+ horsepower at the rear wheels, depending on your cam choice and supporting modifications.

Camshaft Fundamentals: What Makes a “Performance” Cam?

A camshaft is the engine’s mechanical brain. Its lobes control when the intake and exhaust valves open and close, as well as how far they lift. Performance cams alter these events to favor high‑rpm airflow. Key specifications include:

  • Duration – the number of crankshaft degrees the valve stays open. Longer duration fills the cylinder at high rpm but can hurt low‑speed vacuum and idle quality.
  • Lift – the maximum distance the valve opens. Higher lift (combined with adequate spring pressure) allows more air/fuel mixture into the cylinder.
  • Lobe Separation Angle (LSA) – the angle between the intake and exhaust lobe peaks. A tighter LSA (e.g., 108°) increases overlap, strengthening top‑end power but reducing idle smoothness; a wider LSA (114°) broadens the torque curve and improves vacuum for power brakes.
  • Valve Timing Events – also known as “advance” or “retard” built into the cam. Many performance cams are ground 4° advanced to shift torque lower in the rev range.

For a B‑body Mopar that sees street duty, a hydraulic flat‑tappet or hydraulic roller cam with duration around 220°–240° at 0.050″ lift and lift of 0.450–0.550″ is a sweet spot. Roller cams reduce friction and allow more aggressive lobes without accelerated wear, but require compatible lifters and pushrods.

Selecting the Right Camshaft for Your B‑Body

Small‑Block vs. Big‑Block Considerations

Mopar B‑bodies came with both small‑block (LA series) and big‑block (B/RB series) engines. Small‑blocks respond well to cams in the 216–230° duration range, while big‑blocks can handle longer duration due to their larger displacement. Always check piston‑to‑valve clearance before installing a cam with more than 0.500″ lift on a small‑block, or 0.550″ on a big‑block. Machine shops often recommend notching pistons for extreme lifts.

Gauging Your Goals

Be honest about how you drive the car:

  • Street cruiser – choose a “RV” or “torque” cam with short duration (210–220°) and moderate lift. It will improve low‑end grunt without sacrificing idle quality or vacuum.
  • Weekend warrior – a “high‑performance” cam with duration around 224–236° and lift 0.480–0.510″ delivers strong mid‑range and a lumpy idle, especially with a dual‑plane intake and headers.
  • Strip‑focused – longer duration (240–260°) and aggressive lift (0.550–0.650”) demand lightweight valve train parts, high‑stall converter, and likely a single‑plane intake. Not recommended for daily driving.

Brands to Consider

Several reputable manufacturers offer Mopar‑specific grinds: Comp Cams, Lunati, Hughes Engines (specialists in Mopar), and the OEM‑style Mancini Racing offerings. Read customer reviews and dyno sheets to match your exact combination.

Tools and Parts Required for the Swap

Before turning a wrench, gather everything. A missing gasket or tool will stall the job. Here’s a comprehensive list:

  • New performance camshaft (and lifters – always replace lifters when swapping a flat‑tappet cam)
  • Timing chain set (double‑roller recommended for durability)
  • Timing cover gasket set, intake gaskets, valve cover gaskets, and water outlet gasket
  • Valve springs (if cam lift exceeds factory spring capacity) and retainers/locks
  • Engine assembly lube (moly‑based for lobes)
  • High‑volume oil pump (optional but recommended for high‑rpm use)
  • Fresh 10W‑30 or 20W‑50 engine oil and a quality oil filter
  • Basic hand tools: socket set (metric and SAE), wrenches, screwdrivers, pry bar, breaker bar, torque wrench (ft‑lb and in‑lb)
  • Harmonic balancer puller and installer
  • Feeler gauges (for valve lash if solid cam)
  • Timing light and vacuum gauge for tuning
  • Shop rags, degreaser, and a clean workspace

Preparation: Drain Fluids and Set Up the Engine

Begin by disconnecting the negative battery cable. Drain the engine oil and coolant. Remove the radiator (or at least the fan shroud) to give yourself clear access to the front of the engine. If the car has air conditioning, you may need to unbolt the compressor and move it aside without disconnecting the lines. Keep the area dry and clean to avoid debris entering the valley.

Removing the Original Camshaft

Step 1: Strip the Front of the Engine

Remove the serpentine belt or V‑belts, then the water pump pulley, water pump, and harmonic balancer. A puller is essential to remove the balancer without damaging the rubber isolator. Unbolt the timing cover and carefully remove it. The timing chain and gears are now exposed. Rotate the engine by hand until the timing marks align (usually the cam and crank gear dots facing each other). Mark the orientation so you can install the new chain the same way.

Step 2: Remove the Timing Chain and Gears

If the chain has a tensioner, unbolt it. Remove the cam gear bolt (use a holder tool to keep the crank from turning). Slide both gears and the chain off as an assembly. This is a good time to inspect the crank snout for wear.

Step 3: Take Out the Valve Train and Lifters

Remove the intake manifold and valley pan (if equipped). Unbolt the rocker shafts and remove pushrods and lifters. Flat‑tappet lifters must be kept in order if reused, but for a cam swap you should always install new lifters. Store them in a labeled tray. With lifters out, you can finally slide the old cam out through the front of the engine. Be careful not to score the cam bearings – rotate the cam as you pull.

Installing the New Performance Camshaft

Step 4: Lubricate and Insert the New Cam

Coat the cam lobes and journals liberally with high‑modulus moly assembly lube. This is critical for flat‑tappet cams to prevent lobe galling during the first minutes of operation. Slide the cam in slowly, rotating it to avoid scraping the bearings. Once seated, install a new cam button or thrust plate to control end‑play (specs are typically 0.003–0.007″ for Mopar).

Step 5: Install New Lifters and Timing Set

Place new lifters into their bores (oil them with assembly lube). For hydraulic flat‑tappets, pre‑oil the lifter’s internal piston. For hydraulic rollers, ensure the retaining clip is secure. Now install the new timing chain set, aligning the dots exactly as the factory service manual specifies – usually with #1 cylinder at top dead center. Tighten the cam bolt to manufacturer torque specs (often 50–70 ft‑lb on small‑block, more on big‑block).

Step 6: Reassemble the Front of the Engine

Install a new timing cover gasket and the timing cover. Use a thin film of RTV at the bottom corners where the block meets the pan. Install the harmonic balancer with the correct tool, then the water pump, pulleys, belts, and radiator. Reconnect the battery only after the engine is fully reassembled.

Step 7: Valve Train Final Assembly

Install the intake manifold with new gaskets. Lay in the pushrods (check length if using aftermarket heads). Install rocker shafts with rocker arms. For hydraulic cams, adjust the rocker preload to half a turn past zero lash after the pushrod stops turning freely. Solid cams require a feeler gauge to set lash while hot.

Initial Start‑Up and Break‑In Procedure

Before firing, prime the oil system. Remove the distributor and use a priming tool to spin the oil pump with a drill until oil reaches the rockers. Fill the crankcase with fresh oil (a high‑zinc break‑in oil for flat‑tappet cams). Fill the cooling system.

Start the engine and immediately rev it to 2000–2500 rpm – do not let it idle for the first 20 minutes. The cam lobes need splash lubrication to protect the lifters. Watch for oil pressure and water temperature. Walk around the car listening for any valve train clatter or leaks. After the break‑in cycle, let the engine cool, then re‑torque the rocker shafts and check valve lash again.

Expected Power Gains and Supporting Mods

On a well‑tuned B‑body with a performance cam, gains are substantial. A 318 with a 220° intake duration cam can add 25 hp and 30 lb‑ft, while a 440 with a 240° cam can gain 50 hp. However, a cam swap alone is not a silver bullet. To unlock its full potential, combine it with:

  • Headers – long‑tube or shorty headers reduce backpressure and match the cam’s increased flow.
  • Four‑barrel carburetor – an 800–850 cfm carb (e.g., Holley or Edelbrock) feeds the higher airflow.
  • Upgraded ignition system – an MSD or Mopar electronic distributor with a hotter coil ensures complete combustion.
  • Higher‑stall torque converter (if automatic) – a 2500–3000 rpm stall lets the cam operate in its power band from launch.

Tuning for Street Manners

After the break‑in, use a vacuum gauge to set idle mixture and speed. Many performance cams reduce manifold vacuum below 12 inHg, which can annoy power brakes. If needed, install a vacuum canister to maintain brake reserve. Adjust the carburetor’s idle air bleeds or restrictor plates. If the idle is rough, recurve the distributor for more initial timing (12–18° at idle) and limit mechanical advance to 32–36° total. A quality vacuum gauge is invaluable here.

Long‑term Maintenance and Common Pitfalls

A performance camshaft demands more frequent oil changes. Use oil with high zinc/phosphorus (ZDDP) levels for flat‑tappet cams, or a purpose‑built break‑in additive. Retorque intake manifold bolts after 500 miles. Check valve lash annually if using solid lifters. Avoid extended idling, which starves the cam lobes of oil. If you hear a persistent tick after the swap, it’s often a collapsed hydraulic lifter or misadjusted rocker – address it immediately to avoid wiping a lobe.

Conclusion

The B‑body Mopar camshaft swap is a hands‑on project that transforms your car’s personality. Whether you’re chasing quarter‑mile times or simply want that deep, rumbling idle, the process is rewarding and well within the reach of a home mechanic with basic tools. By selecting the right cam, preparing thoroughly, and following a careful break‑in, you’ll gain reliable horsepower and a driving experience that connects you to Mopar’s high‑performance heritage. Start gathering your parts, clear your weekend, and get ready to wake up that Big Block or small‑block.