Why Upgrade to an Edelbrock RPM Intake on Your 1967 Barracuda?

If you own a 1967 Plymouth Barracuda, you already know that this iconic first-generation pony car is a platform with serious potential. The Slant Six and small-block V8 engines that powered these cars are reliable, but they left a lot of power on the table from the factory. One of the most effective bolt-on upgrades you can make is swapping the restrictive stock cast-iron intake manifold for an aftermarket aluminum unit. The Edelbrock RPM intake manifold is a legendary choice for this application. Designed for high-performance street and strip use, it delivers a broad power band and significantly improves airflow over the factory piece. The result is sharper throttle response, more top-end horsepower, and often better fuel efficiency when tuned correctly. This guide will walk you through the entire installation process, from gathering the right tools to troubleshooting common issues, so you can get the most out of your classic Barracuda.

Tools and Materials You Will Need

A successful intake swap starts with being properly prepared. Don’t cut corners; having everything on hand before you get greasy will save you frustration and prevent damage to your new Edelbrock manifold. Here is a comprehensive list of tools and supplies required for the job:

Tools

  • Torque wrench (ft-lb and in-lb)
  • Socket and ratchet set – ¼-inch, ⅜-inch, and ½-inch drive depending on bolt sizes
  • Combination wrenches – metric and SAE (mostly SAE for a ‘67 Barracuda)
  • Screwdrivers – flathead, Phillips, and possibly a stubby
  • Pliers (regular and needle-nose)
  • Gasket scraper or razor blade
  • Wire brush
  • Flashlight or inspection light
  • Vacuum gauge (optional but useful for tuning)
  • Carburetor adjustment tools (if reusing a Holley or Edelbrock carb)

Parts and Materials

  • Edelbrock RPM intake manifold (check part number for your specific engine: small-block Chrysler 273, 318, or 340—the 1967 Barracuda typically came with a 273 or 318, but the RPM works on most LA small-blocks)
  • Intake gasket set – use high-quality Fel-Pro or Edelbrock gaskets; avoid paper-thin generic sets
  • Permatex Right Stuff or similar high-temp silicone gasket maker (for end seals)
  • Thread locking compound – Loctite 242 (blue) for manifold bolts
  • Anti-seize compound (for spark plugs and header bolts if applicable)
  • Clean rags – lint-free preferred
  • Brake cleaner or carb cleaner
  • Engine oil (to lubricate bolt threads as per manufacturer spec)
  • Safety glasses
  • Mechanics gloves

Preparation: Getting the Car Ready for Surgery

Before you start turning wrenches, it is critical to prepare your 1967 Barracuda properly. A cool engine is non-negotiable—aluminum burns are painful and slow to heal. Park the car on level ground, engage the parking brake, and chock the rear wheels. Disconnect the negative battery cable to eliminate any chance of shorts or accidental starter engagement. Next, drain the engine coolant if your intake manifold has coolant passages (most Chrysler small-blocks do). Open the radiator drain petcock and remove the radiator cap to speed up the flow. You will also need to remove any accessories that block access to the intake. This typically includes the air cleaner assembly, carburetor, fuel lines, vacuum lines, throttle cable, and any brackets for the alternator or power steering if they mount to the intake. Label everything with painter’s tape and a marker—your future self will thank you.

Checklist Item Status
Engine cold to the touch ✔
Negative battery cable disconnected ✔
Coolant drained (if manifold has water passages) ✔
Air cleaner, carburetor, and linkages removed ✔
All vacuum lines and electrical connectors labeled and removed ✔
Accessory brackets unbolted and set aside ✔

Removing the Stock Intake Manifold

With everything disconnected, you can begin removing the factory intake. The stock cast-iron manifold on a 1967 Barracuda is heavy—often 50 pounds or more—so have a helper nearby or use a proper lifting technique. Start by removing the bolts that hold the intake to the cylinder heads. Usually, these are 5/16-inch or 3/8-inch hex bolts. Use a penetrating oil like WD-40 or PB Blaster on stubborn bolts and let it soak for a few minutes. Loosen each bolt in a reverse of the factory torque sequence (center outward) to prevent warping the manifold. Once all bolts are removed, carefully pry the manifold loose from the engine block. Do not use excessive force that could damage the heads or gasket surfaces. Lift the manifold straight up and off the engine.

Cleaning the Engine Deck Surfaces

This is the most critical step for a leak-free installation. After removing the old manifold and gaskets, you must thoroughly clean the mating surfaces on the cylinder heads and the timing chain cover (if applicable). Use a gasket scraper or a razor blade—be careful not to gouge the aluminum or cast iron. Follow up with a wire brush and brake cleaner to remove any residue, oil, or coolant. A clean surface is essential for the new gaskets to seal properly. If you intend to reuse your stock valve covers, now is also a good time to clean them and replace the gaskets.

Pro tip: Place clean shop rags in the intake ports and lifter valley openings while you work. Even a small piece of debris dropped into an oil passage can destroy your engine.

Installing the Edelbrock RPM Intake Manifold

Now the fun begins. Unbox your new Edelbrock RPM manifold and inspect it for any shipping damage or debris inside the runners. Clean it with brake cleaner if necessary. Lay out the new gaskets—the Edelbrock kit often comes with two styles: one for a standard port and one for the “RPM” raised port. Use the correct gasket for your cylinder head (if you have aftermarket heads, confirm port size). Place the gaskets dry onto the cylinder head surfaces; do not apply any sealant unless specified by the gasket manufacturer. For the front and rear end seals (where the manifold meets the block), apply a high-quality RTV silicone gasket maker like Permatex The Right Stuff. Put a thin, even bead on the block where the rubber gasket would sit, then lay the rubber seal in place. Some professionals replace the rubber end seals with a thick bead of RTV alone—this can be more reliable for preventing leaks.

Setting the Manifold in Place

Carefully lower the Edelbrock RPM manifold onto the engine, aligning the runners with the intake ports. Make sure the end seals stay in place. Install the bolts by hand—do not use a power tool yet. Edelbrock uses a specific bolt pattern and torque sequence. Refer to the instructions that came with your manifold. For most LA small-blocks, the torque sequence is as follows:

  1. Center bolts first
  2. Moving outward to the ends
  3. Alternate between front and rear bolts in a crisscross pattern

Tighten all bolts finger-tight first to seat the manifold evenly, then use your torque wrench.

Torque Specifications

Incorrect torque can crack the manifold or cause vacuum leaks. For the Edelbrock RPM intake on a Chrysler small-block, the standard torque is 45–50 ft-lbs for the 5/16-inch bolts (typically used in the center positions) and 30–35 ft-lbs for the 3/8-inch bolts (some end positions). Always verify with the current Edelbrock instruction sheet as specifications can change. Tighten in three progressive steps: first to 15 ft-lbs, then 30 ft-lbs, then final torque value. Wait 10–15 minutes, then re-torque once more to account for gasket compression. Apply a small drop of blue Loctite to each bolt to prevent them from backing out over time.

Reconnecting Everything: Carburetor, Linkages, and Accessories

Once the intake is bolted down and the RTV has had time to cure (check the manufacturer’s cure time—typically 30 minutes to 1 hour), you can start reassembling. Install the carburetor with a new gasket or heat insulator. Edelbrock recommends using their included paper gasket over a phenolic spacer if you have the room. Reconnect the throttle linkage, vacuum lines, fuel line, and any electrical connectors you removed earlier. If your Barracuda has a mechanical fuel pump, ensure the pushrod is properly seated in the block; the new manifold may change the clearance. You will also need to reconnect the distributor vacuum advance hose to the correct port on the carburetor—use a manifold vacuum port for better idle quality on a performance cam. Before you close the hood, double-check that no loose tools or rags remain in the engine bay.

Initial Start-Up and Tuning

With everything connected, fill the cooling system with a 50/50 mix of coolant and distilled water. Pour it slowly to avoid trapping air. Reconnect the battery. Check the oil level and top off if needed. For the first start, squirt a little fuel into the carburetor to prime the system if the engine has been sitting. Crank the engine without the distributor connected until oil pressure registers on the gauge, then reconnect the ignition. Start the engine and let it idle at around 1,000 RPM. Immediately check for vacuum leaks—listen for hissing and spray carb cleaner around the intake gasket surfaces; if idle speed changes, you have a leak. Also check for coolant leaks around the thermostat housing and the end seals. Let the engine come up to operating temperature (about 180°F), then check the idle mixture screws on the carburetor. Adjust them for maximum vacuum and smooth idle. Re-torque the intake bolts once more after the first heat cycle—this is often forgotten but is critical for long-term sealing.

Performance Expectations and Results

After installing the Edelbrock RPM intake, you should notice an immediate improvement in throttle response and mid-range torque. On a typical 1967 Barracuda 273 or 318 with a mild cam and headers, the power gain is typically 15–25 horsepower at the flywheel. With a more aggressive setup (e.g., 340/360 heads, larger cam, 4-barrel carb), gains can exceed 30 horsepower. The RPM intake’s dual-plane design also helps maintain good low-speed drivability, making it an excellent choice for the street. For more on tuning, check out Edelbrock’s official support page and For A Bodies Only for community advice. Additionally, Hot Rod magazine has published dyno comparisons of popular intake manifolds.

Common Pitfalls and Troubleshooting

Even a straightforward install can present challenges. Here are the most common issues:

  • Vacuum leaks at the manifold-to-head gasket: Usually caused by insufficient cleaning or improper torque sequence. Fix: Remove, clean, re-gasket.
  • End seal oil leaks: Often from the rubber gasket squishing out. Solution: Use a thick bead of RTV instead of the rubber seal.
  • Distributor interference: Some RPM manifolds place the distributor hole slightly higher. You may need a shorter distributor hold-down bracket or extra shimming.
  • Clutch linkage binding: On manual transmission Barracudas, the Z-bar may contact the manifold. Minor clearancing with a file is sometimes needed.
  • Carburetor base gasket mismatch: Ensure the throttle bores align with the manifold plenum. Edelbrock carburetors are a natural match for this manifold.

Final Thoughts

Swapping a stock cast-iron intake for an Edelbrock RPM manifold on your 1967 Barracuda is one of the most satisfying upgrades you can do in a weekend. It improves power, saves weight, and gives your engine bay a more performance-oriented look. With attention to detail—especially in surface preparation, torque sequence, and heat cycling—you can enjoy a leak-free installation that performs reliably for years. Whether you are cruising to a car show or pushing the car hard on backroads, the Edelbrock RPM intake is a proven upgrade that helps your Barracuda wake up.