Upgrading a Chevy 350 is one of the most rewarding projects an enthusiast can tackle. I recently invested $2,500 in a camshaft and exhaust upgrade, and the result was a verified 80-horsepower gain at the rear wheels. This isn’t a theoretical build – it’s a real-world example of how choosing the right components and doing the work properly can transform a tired small-block into a genuinely potent powerplant. Below I break down every aspect of the build: why I chose each part, the installation process, dyno results, and the day-to-day driving experience.

Why the Chevy 350 Remains a Builder’s Favorite

The Chevrolet small-block V8, particularly the 350 cubic inch (5.7L) variant, has been a cornerstone of American performance since its introduction in 1967. Its cast-iron block offers excellent durability, parts availability is virtually unmatched, and the aftermarket support is staggering. Even a stock 350 from the 1970s or ‘80s can be a solid foundation for upgrades. My engine was a mid-1980s truck version, rated at roughly 210 horsepower from the factory – a far cry from its potential. The combination of low-end torque and a well-understood architecture makes the 350 ideal for camshaft and exhaust modifications.

Unlike modern engines with variable valve timing and complex ECU controls, the Chevy 350 responds directly to mechanical changes. Swap in a more aggressive cam, free up the exhaust flow, and the engine announces the improvement immediately. That transparency is part of what makes the build so satisfying.

Camshaft Upgrade: The Heart of the Power Gain

The camshaft controls when the intake and exhaust valves open and close. A stock 350 camshaft is designed for fuel economy, idle smoothness, and emissions compliance – not peak power. By upgrading to a performance cam with increased lift and duration, you allow more air/fuel mixture into the cylinders and expel exhaust gases more efficiently. That directly translates to higher horsepower, especially in the mid-to-upper RPM range.

Choosing the Right Cam Profile

Selecting a cam isn’t just about picking the biggest numbers. I had to balance street drivability with power goals. Key specifications I considered:

  • Duration – Measured in degrees of crankshaft rotation. A duration around 270–280 degrees (advertised) gives strong mid-range power without killing vacuum for power brakes.
  • Lift – How far the valve opens. With a matching spring upgrade, 0.480–0.520 inch lift is a safe range for a street 350 with stock-style heads.
  • Lobe Separation Angle (LSA) – A 112-degree LSA provides a compromise between idle quality and top-end power. Tighter LSA (108) gives more peak HP but rough idle and less vacuum.
  • Valve Timing Events – Intake centerline and overlap affect where the power band lives.

I settled on a hydraulic flat-tappet cam from Comp Cams’ Xtreme Energy series, specifically the XE268H. Its 268/268 degrees duration and 0.477/0.480 inch lift (with 1.5:1 rockers) promised a noticeable power increase from 1,500 to 5,500 RPM while retaining enough manifold vacuum for the elderly Quadrajet carburetor. I also upgraded the valve springs, retainers, and timing chain to handle the increased lift without valvetrain float.

Supporting Mods Required for a Cam Swap

A camshaft upgrade is not a drop-in affair. The piston-to-valve clearance must be checked, especially on engines with stock cast pistons. I verified clearance using modeling clay (a common technique). Additionally, the carburetor needed re-jetting, the distributor required recurving, and the idle mixture screws had to be adjusted for the new cam’s overlap. Without these supporting changes, the cam won’t deliver its full potential.

Exhaust Upgrade: Letting the Cam Breathe

Installing a bigger cam without improving exhaust flow is like breathing through a straw while running a marathon. The stock exhaust manifolds and single 2.25-inch pipe on my pickup were choking the engine. A performance exhaust system reduces backpressure and allows scavenging, where the exhaust pulses create a low-pressure wave that pulls out more exhaust gas. This effect works hand-in-hand with increased cam overlap.

Header Selection

I chose long-tube headers over shorty headers because long tubes provide superior mid-range and top-end torque due to better primary length tuning. The set I installed featured 1.625-inch primary tubes and 3-inch collectors, a common street-strip combination for a 350. Flowmaster headers with thick flanges minimized leakage. Ceramic coating helped reduce under-hood temperatures, which is a bonus for daily driving.

Muffler and Exhaust System

Downstream from the headers, I ran a dual 2.5-inch system with an H-pipe crossover. The H-pipe balances pressure between banks, improving low-end torque and reducing exhaust drone. For mufflers, I used Borla Pro XS straight-through mufflers. These are free-flowing yet relatively quiet at cruise – important for a street-driven vehicle. The total exhaust system (headers, pipes, mufflers, hangers) cost $650, including ceramic coating.

One detail often overlooked: the oxygen sensor. Because my engine used a carburetor, there was no factory O₂ feedback. However, for those converting to fuel injection or adding a wideband sensor for tuning, bungs in the collector make datalogging possible.

Installation Process: What It Really Takes

Performing a cam and exhaust swap on a Chevy 350 in a garage is achievable with basic mechanical skills, but it requires patience and the right tools. I documented the major steps:

Tools and Preparation

  • Engine hoist or cherry picker (not strictly necessary but makes removing the radiator and accessing cam bolts easier)
  • Socket set, torque wrench, breaker bar
  • Cam bearing installer (or machine shop service)
  • Valve spring compressor
  • Flat-tappet cam lube (critical for break-in)
  • Timing tape and timing light
  • Carburetor tuning kit (air/fuel ratio meter helpful)

Camshaft Removal and Installation

  1. Disconnect battery and drain coolant. Remove radiator, fan, and shroud.
  2. Remove valve covers, intake manifold, and distributor. Mark distributor rotor position before removal.
  3. Remove rocker arms, pushrods, and lifters. Keep lifters in order if reusing, but for a cam upgrade, new lifters are mandatory.
  4. Remove timing cover and chain. Remove cam gear – using a puller is safest.
  5. Remove camshaft bolts (most Chevy cams use a single bolt or three bolts). Slide cam out carefully to avoid damaging cam bearings. Note: some engines require removing the grille to slide the cam out from the front.
  6. Lube the new cam with proper break-in oil additive (e.g., Lucas break-in oil). Install cam, timing chain set at correct cam-crank indexing (dot-to-dot for standard timing).
  7. Install new lifters, pushrods, and rocker arms. Adjust valve lash if using mechanical rockers, or preload for hydraulic lifters.
  8. Reinstall timing cover, distributor (re-index the rotor), intake manifold, and carburetor.

Exhaust System Installation

  1. Remove existing exhaust manifolds, downpipes, and mufflers. Penetrating oil is your friend on rusted bolts.
  2. Install headers with new gaskets (copper or high-temp graphite). Tighten evenly in sequence.
  3. Route collector pipes and install the H-pipe crossover. Mufflers are clamped after.
  4. Check clearance from starter, oil filter, and steering linkage. May need to dimple header tubes for clearance – common on Chevy trucks.

Break-in Procedure

Driving a new cam requires a specific break-in period. With flat-tappet cams, the lifters need to rotate initially to prevent lobe wear. The process: start engine and immediately bring RPM to 2,000–2,500 for 20 minutes, varying RPM slightly. Use heavy zinc oil (ZDDP additive) to protect the cam lobes. After break-in, check valve lash and change oil and filter.

Dyno Results: 80 HP Gained

Before the upgrade, my Chevy 350 laid down 198 horsepower and 285 lb-ft of torque at the rear wheels (corrected to SAE J1349). These numbers are typical for a stock 350 with exhaust manifolds and a worn-in cam.

After the cam and exhaust swap – and after dialing in the carburetor and timing – the same dyno showed 278 horsepower and 338 lb-ft of torque. That’s a gain of 80 horsepower and 53 lb-ft. The power curve shifted noticeably: peak horsepower moved from 3,800 RPM to 4,600 RPM, and peak torque increased by 20 lb-ft at 3,000 RPM. The H-pipe and long-tube headers clearly helped mid-range; the torque curve was flat from 2,500 to 4,500 RPM.

Further gains could come from ported heads or a more aggressive cam, but for street reliability and budget, this combination hit the sweet spot. The $2,500 total spent breaks down as follows:

  • Camshaft kit (cam, lifters, springs, timing set): $450
  • Carburetor re-jetting and tuning supplies: $75
  • Valve cover gaskets, intake gaskets, timing cover gasket: $60
  • Headers (ceramic-coated long-tube): $550
  • Dual exhaust kit (pipes, H-pipe, mufflers, clamps): $650
  • Dyno tuning session (3 runs with wideband): $250
  • Oil, filter, break-in additive, coolant: $75
  • Miscellaneous tools/penetrating oil: $40
  • Total: $2,150 – under $2,500, with surplus for unexpected parts.

The remaining $350 went toward a new thermostat, water pump, and spark plugs (gap increased for wider plug gap with hotter ignition).

Driving Experience and Street Manners

On the road, the difference was dramatic. The engine pulled strongly from 2,000 RPM, and by 3,000 it felt like a different motor. The idle was slightly lumpy – around 750 RPM with a mild lope, enough to tell you something was different but not obnoxious. Vacuum at idle dropped from 16 inHg to 12 inHg, which still operated the power brakes without issue.

Throttle response sharpened: tip-in from a stoplight felt immediate, and part-throttle cruising required less pedal input to maintain speed. The exhaust note changed from a dull drone to a crisp, aggressive bark on acceleration, settling into a deep rumble at highway speeds. Drone was minimal thanks to the H-pipe and the Borla mufflers’ packed design.

Fuel economy? Surprisingly, it improved slightly on the highway – from 14 MPG to 15 MPG – because the engine no longer had to work as hard to maintain speed. City mileage dropped a tad due to richer mixture at idle, but overall the trade-off was worth it.

This build is intended for off-road or weekend use. Headers that delete catalytic converters violate federal emissions regulations for street-driven vehicles in many states. Be sure to check local laws before undertaking such a project. If you live in California or other states with smog checks, a carbureted 350 with a cam swap and aftermarket exhaust will almost certainly fail visual and tailpipe tests unless you retain catalytic converters and keep the system emissions-legal.

Conclusion: Is a $2,500 Cam and Exhaust Upgrade Worth It?

Yes – unequivocally. An 80-horsepower gain for $2,500 works out to $31.25 per horsepower, which is outstanding value compared to forced induction or cylinder head work. The combination of a well-chosen camshaft and a free-flowing exhaust system is the most cost-effective way to wake up a small-block Chevy. The driving experience is transformed: the engine feels alive, responsive, and powerful throughout the RPM range.

However, this upgrade is not for everyone. If you value stock idle quality, absolute silence from the exhaust, or absolute reliability without any tuning, a cam and exhaust swap may introduce compromises. But for those seeking a tangible, seat-of-the-pants improvement that makes every drive engaging, this $2,500 investment delivers more smiles per mile than almost any other modification. I would do it again without hesitation.