The 1968 Dodge Charger: An Icon Reborn

The 1968 Dodge Charger is more than just a car; it is a landmark of American automotive design. Its aggressive fastback roofline, hidden headlights, and "flying buttress" rear pillars created a silhouette that was instantly recognizable and fiercely intimidating. It was the car that Dodge used to break the bank at NASCAR, and it cemented its place in pop culture forever. For enthusiasts, owning a '68 Charger is a dream. But the stock 383 Magnum, while respectable in its day, often leaves modern drivers wanting more. This is the story of how a carefully curated selection of Summit Racing components liberated an additional 100 horsepower from a classic 383, transforming a cruiser into a serious street predator.

The Foundation: The 383 Magnum V8

Before discussing the upgrades, we need to understand the platform. The 383 cubic-inch V8 is a raised-block version of Chrysler's B-series engine. It featured a 4.25-inch bore and a 3.38-inch stroke. In stock '68 Charger trim, the 4-barrel version was rated at 335 horsepower. However, that rating was measured using the old SAE gross standard, which did not account for accessories, exhaust restrictions, or driveline losses. In reality, under the hood options like power steering, air conditioning, and a restrictive cast-iron intake manifold choked the engine significantly.

The stock components were durable but heavy and inefficient. The cast-iron intake manifold was a prime culprit, retaining immense heat and restricting airflow. The factory exhaust manifolds were log-style units that strangled the engine's ability to breathe. The ignition system was a rudimentary points-style setup prone to wear and misfire at higher RPMs. To unlock the latent power inside the 383, these bottlenecks had to be removed.

Why Summit Racing?

For this project, we sourced the majority of the performance parts from Summit Racing. Their house-brand components offer an exceptional balance of cost and performance, backed by real-world testing and engineering support. Summit Racing provides a massive catalog of parts specifically curated for classic muscle cars, making them a one-stop shop for a project of this scale.

Summit Racing Equipment: A Trusted Source

Summit Racing Equipment has been a pillar of the automotive aftermarket since 1968. They offer everything from gaskets and bolts to complete crate engines. For the classic Mopar enthusiast, their house brand components—such as intake manifolds, camshafts, and ignition systems—are designed to offer significant performance gains without the price premium of vintage boutique brands. They also provide detailed tech support, helping enthusiasts choose the right combination of parts for their driving style and vehicle setup.

The Induction System: Letting the Engine Breathe

The first major bottleneck was the stock induction system. The heavy cast-iron intake was swapped for a Summit Racing aluminum dual-plane intake manifold. This immediately shaved nearly 30 pounds off the front of the engine. More importantly, the dual-plane design separates the engine into two 4-cylinder groups, optimizing low-rpm velocity for excellent street manners while still providing a high-flow top end.

On top of the new intake, we placed a Summit Racing 750 CFM vacuum-secondary carburetor. The 750 CFM rating is a perfect match for a street 383, providing ample airflow without killing low-speed throttle response. The vacuum secondaries ensure that the driver has predictable, controllable power on demand. Tuning was simplified with interchangeable metering blocks and power valves, allowing us to dial in the air-to-fuel ratio for optimal performance on 93-octane pump gas.

Exhaust Scavenging: Summit Racing Headers

Getting the exhaust out is just as important as getting the air and fuel in. We replaced the restrictive cast-iron exhaust manifolds with a set of Summit Racing full-length headers. These headers feature 1.625-inch primary tubes and a 3-inch collector. The long primary tubes create a strong exhaust scavenging effect, pulling spent gases out of the cylinders and drawing in the fresh air-fuel mixture. This dramatically improves volumetric efficiency across the entire RPM range.

The result was a noticeable drop in under-hood temperatures and a much deeper, more aggressive exhaust note. The headers paired perfectly with a 3-inch mandrel-bent exhaust system, featuring an H-pipe crossover to balance the pulses and maximize torque. The reduction in backpressure was a huge contribution to our overall horsepower gain, likely accounting for 25 to 30 of those 100 added horses.

Valvetrain and Camshaft: The Heart of the Build

The single biggest contributor to the horsepower increase, however, was the camshaft. We selected a Summit Racing hydraulic flat-tappet camshaft specifically ground for street performance. The specifications are a 230/234 degree duration at .050-inch lift and a .488/.491-inch valve lift with a 110-degree lobe separation angle.

Choosing the Right Cam for the 383

This camshaft profile represents an excellent middle ground for a 383 street car. It provides a very distinct, aggressive "muscle car" idle that announces its presence with authority. More importantly, it moves the power band up, allowing the engine to pull hard all the way to 6000 RPM. We paired the cam with a set of Summit Racing valve springs, retainers, and locks to ensure the valvetrain could handle the increased lift and RPM without floating. We also installed high-quality Summit Racing timing chain and gear set to ensure precise cam timing and durability.

The camshaft installation requires careful attention to geometry. We degree the cam to ensure the intake centerline is exactly where the manufacturer specifies. This guarantees that the piston-to-valve clearance is safe and that the power band delivers as intended. With the improved cam profile, the 383 went from being a lazy torque monster to a high-winding powerhouse.

Ignition: Firing the Charge

The stock points-style ignition was replaced with a Summit Racing ready-to-run electronic distributor. This is a crucial upgrade for reliability and performance. The electronic ignition provides a hot, consistent spark at all RPMs, eliminating the "points bounce" that limited the stock engine to around 5000 RPM.

This distributor features a mechanical advance curve that we can tune by changing springs and stop bushings. For the 383 build, we dialed in a progressive advance curve, bringing the total timing to 34 degrees by 2800 RPM. This provides crisp throttle response off idle and clean, knock-free power at wide-open throttle. The hotter spark also ensures more complete combustion of the air-fuel mixture, improving fuel economy and throttle response. We backed this up with a Summit Racing high-performance ignition coil and 8mm spark plug wires.

The Dyno Results: Cold, Hard Facts

After breaking the engine in with a careful camshaft break-in procedure and driving the car for 500 miles, we strapped the 1968 Charger to a chassis dyno. The results were exactly what we were hoping for:

  • RWHP Before Upgrades: 225 RWHP (estimated baseline representing real-world wheel horsepower)
  • RWHP After Upgrades: ~325 RWHP
  • Estimated Crankshaft Horsepower Gain: +100 HP (from 335 gross to a stable 435+ gross).

While the dyno numbers are great, the torque curve is what truly impressed us. The engine made over 450 lb-ft of torque from 2800 RPM all the way past 5000 RPM. This flat, broad torque curve is a testament to the excellent cam and intake combination. The car now pulls harder at 5500 RPM than it ever did at 3000 RPM.

Driving Impressions and Real-World Feel

Driving the Charger after the upgrades is a completely different experience. The throttle pedal is now a serious accelerator. A stab of the gas results in an immediate surge of power and a glorious wail from the Summit headers.

  • Idle Quality: The camshaft provides a distinct, choppy idle that sounds menacing.
  • Throttle Response: Crisp and immediate. The Summit carburetor and ignition combination eliminated the flat spots that plagued the stock engine.
  • Acceleration: The car now demands respect. Keeping the tires hooked requires a gentle right foot and a well-set-up suspension.
  • Reliability: Despite the massive power increase, the car starts easily, idles well in traffic, and runs cool on the highway. The Summit Racing components have proven to be reliable in real-world street driving.

Supporting Mods: Making the Power Usable

Adding 100 horsepower naturally stresses the rest of the driveline. To ensure the Charger could handle the power, we upgraded a few supporting components.

Cooling and Fuel Delivery

We installed a Summit Racing high-flow water pump and a four-core aluminum radiator to keep the 383 cool during summer traffic. On the fuel side, we upgraded the mechanical fuel pump to a high-volume unit from Summit to ensure the carburetor never ran dry under hard acceleration.

Driveshaft and Gearing

While not strictly necessary for 435 hp, the stock 2.94 or 3.23 gears hold the car back. Matching the Charger’s 727 TorqueFlite transmission to a 3.55 or 3.73 limited-slip rear end would unlock even more performance, allowing the car to launch harder and use the power band more effectively. For this project, we retained the stock 3.23 gears, but a gear swap is the next logical step.

Project Cost vs. Performance Value

One of the most impressive aspects of this build is the cost-to-power ratio. The entire Summit Racing catalog order—including the intake, carburetor, camshaft, lifters, timing set, valve springs, spark plugs, wires, distributor, coil, and headers—was completed for well under $2,500. Achieving a 100-horsepower gain for this price point is a phenomenal return on investment compared to adding a supercharger or performing a full stroker motor build.

For enthusiasts looking to wake up their classic Mopar, this combination of Summit Racing components proves that you don't need a exotic engine swap to have world-class performance. The 383 Dodge Charger can be turned into a true 400+ horsepower street machine with a careful, well-researched parts list and a weekend's worth of work in the garage. The result is a car that retains its original engine, its classic character, and its massive potential for sheer, unadulterated driving fun.

Conclusion: The Stripe is Back

The 1968 Dodge Charger is a masterpiece of automotive design. By upgrading it with modern aftermarket parts, we haven't just made it faster—we have made it more reliable, more efficient, and infinitely more enjoyable to drive. This project showcases the incredible potential sitting inside the stock small-block Mopar engine and proves that Summit Racing equipment is an excellent tool for unleashing it. Whether you are cruising a car show or hunting down the next stoplight, a properly tuned 383 with a good set of heads and an intake from Summit is a force to be reckoned with.