Installing Headman Headers can dramatically improve your vehicle's exhaust flow, unlocking hidden horsepower and torque. However, a successful installation demands more than just bolting on parts. Achieving a leak-free, high-performance fit requires meticulous preparation, proper technique, and an understanding of how headers interact with your engine's tuning. This comprehensive guide provides detailed tips and expanded procedures to ensure your Headman Headers deliver their full potential.

Understanding Headman Headers

Headman Headers, a respected name in the aftermarket performance industry, are engineered to replace restrictive factory exhaust manifolds. By using individual tubes that merge into a collector, they reduce backpressure and promote better exhaust scavenging—the process by which exiting gases help pull the next charge of exhaust out of the cylinder. This effect directly increases volumetric efficiency, leading to gains in horsepower and torque across the RPM range. Headman offers several header types to suit different applications: shorty headers (emissions-friendly, easy fit), mid-length headers (balance of torque and top-end power), and full-length long-tube headers (maximum high-RPM performance, often requiring exhaust system modifications). Materials also vary: mild steel with ceramic coating for durability and heat rejection, or 304 stainless steel for corrosion resistance and a polished look. Choosing the right header design for your vehicle’s engine bay, intended use (street, strip, or towing), and local emissions regulations is critical.

Preparation Before Installation

Proper preparation is the cornerstone of a smooth header installation. Rushing this phase leads to stripped bolts, leaks, and damaged components. Begin by gathering all necessary tools and supplies. In addition to the basics, have penetrating oil, a tap and die set (for cleaning threads), a gasket scraper, and a mirror for inspecting hard-to-see areas. It is also wise to have new exhaust gaskets specifically designed for header applications—avoid cheap paper gaskets; high-quality multi-layer steel (MLS) or dead-soft copper gaskets are superior for sealing and heat resistance.

  • Ratchet and socket set (metric and SAE; include deep sockets for header bolts)
  • Torque wrench (capable of reading inch-pounds for small bolts and foot-pounds for header bolts)
  • Pipe cutter or reciprocating saw (if modifying exhaust to match collector position)
  • High-temperature thread locker (Loctite 242 or similar) and nickel-based anti-seize compound
  • Safety equipment: goggles, gloves, and a fire extinguisher (fuel lines may be near)
  • Jack and jack stands (never rely on a hydraulic jack alone)
  • Booster cable or battery charger (to keep battery voltage stable if engine is started for leak check)

Before you begin, spray all exhaust manifold bolts with penetrating oil. Let it soak for at least 30 minutes. Disconnect the negative battery terminal to prevent accidental starting. Raise the vehicle securely, ensuring you have enough clearance to work from above and below. Cover exposed engine openings with clean rags to prevent debris entry.

Step-by-Step Installation Process

1. Remove Old Exhaust Manifolds and Components

Start by removing any components that block access to the exhaust manifolds—spark plugs, heat shields, O2 sensors, and sometimes the starter on certain V8 layouts. Carefully unscrew the manifold bolts. If a bolt is seized, apply heat with a propane torch (near the head) and use an impact driver. Never force a bolt without heat or penetrating oil—broken exhaust bolts in aluminum cylinder heads are a costly repair. Once all bolts are out, gently pry the manifold from the cylinder head; avoid damaging the head’s sealing surface. Remove the old gasket and scrape all residue clean with a plastic or brass scraper.

2. Prepare the Surface and Check Fitment

Before installing the new headers, test-fit them while the engine is cold. Hold the header in place and verify clearance against the frame, steering shaft, spark plugs, and wiring. Do not force the header into position; if it contacts anything, you may need to loosen engine mounts and shift the engine slightly, or use a small dimple die on the header tube (if using mild steel). Clean the cylinder head mounting surface with brake cleaner and a lint-free cloth. Lightly sand any high spots with 400-grit sandpaper on a flat block. Do not use a wire wheel on aluminum heads—it can gouge the surface. Apply a thin film of high-temperature anti-seize to the header bolt threads (except those that require thread locker, noted in step 3).

3. Install the Headers

Position the header gasket on the studs or bolt holes. Many header manufacturers recommend using smeared ultra-copper RTV on both sides of the gasket for an initial seal. Carefully lower the header onto the gasket. Start all bolts by hand to ensure they engage threads evenly. Do not tighten any bolt fully until all bolts are started—this prevents cross-threading and allows the header to seat squarely. Use a torque wrench to tighten in a cross-pattern sequence, going to the manufacturer's specification (typically 15–25 ft-lbs for mild steel headers, lower for stainless). Recheck torque twice: once immediately after initial tightening, and again after the engine has warmed up (see post-installation section). For headers that use a separate flange gasket (like some shorty applications), ensure the gasket is centered on the port holes.

4. Connect the Exhaust System

With the headers in place, attach the remaining exhaust components (downpipe, catalytic converters, or test pipes). You may need to cut or lengthen the exhaust pipe to align with the collector. Use a quality band clamp or v-band for a secure, leak-free connection. For slip-fit collectors, a small tack weld or clamp is advisable. Ensure all hangers and supports are attached loosely before final tightening—adjust pipe angles to avoid stress on the headers. Tighten all connections to 30–40 ft-lbs (or per clamp manufacturer).

5. Install O2 Sensors and Heat Protection

Reinstall oxygen sensors into the header’s dedicated bungs. Apply anti-seize to the sensor threads only if specified by the sensor manufacturer; many modern sensors come pre-coated. If the header does not have a bung in the correct location, an extension harness may be needed. Consider adding thermal barrier wrap (header wrap) to reduce underhood temperatures and protect wiring, though note that wrapping can accelerate tube corrosion if the tubes are not coated. Alternatively, use heat shields or reflective tape on nearby components.

6. Check for Leaks and Final Torque

Start the engine and let it idle to operating temperature. Listen for “ticking” sounds that indicate a leak at the header-to-head joint or connections. Spray soapy water around each port; bubbles reveal a leak. If a leak is found, shut off the engine, allow it to cool, and retorque the bolts. After the engine has been run and cooled down, retorque all header bolts (typically after the first heat cycle). This step is critical because metal expands and gaskets compress, causing bolts to loosen. Use a torque wrench to verify each bolt is at spec. Recheck again after 100 miles.

Tips for Optimal Performance

Getting the headers on is only half the battle. To maximize the investment, follow these performance-enhancing practices:

  • Tune for the headers. Headers change the engine’s air/fuel ratio and backpressure characteristics. A custom ECU tune (via a handheld tuner or dyno session) can adjust fuel and spark tables to fully exploit the increased flow. Even a plug-and-play tune from a reputable vendor yields noticeable gains.
  • Use high-quality gaskets. Avoid the cheap paper gaskets that often come with budget header kits. Replace them with multi-layer steel (MLS) or embossed copper gaskets. They withstand high temperatures and repeated thermal cycling better.
  • Manage heat. Uncoated mild steel headers radiate immense heat into the engine bay, which can deteriorate plug wires, hoses, and sensors. Apply high-temperature ceramic coating (either a DIY spray or professional service) or wrap the tubes. Coated headers also reduce underhood temps and retain exhaust gas velocity.
  • Prevent bolt loosening. Header bolts are notorious for backing out due to vibration. Use grade 8 bolts with integrated lock washers or stage 8 locking fasteners. Apply medium-strength thread locker (blue Loctite) to the bolts, but note that if you need to remove them often, red Loctite may be too aggressive. Re-torque at every oil change.
  • Upgrade the exhaust system. Headers paired with a larger-diameter, mandrel-bent exhaust system (2.5 or 3 inches) and a high-flow catalytic converter free up additional horsepower. A cat-back system with straight-through mufflers (like Magnaflow or Borla) complements the header’s flow.
  • Consider O2 sensor extensions. If the header collector is far from the factory O2 sensor location, use an extension harness. Avoid splicing wires, as signal degradation affects fuel trims.

Common Issues and Troubleshooting

Even with careful installation, some issues may arise. Here are solutions to frequent problems:

  • Exhaust Leaks at the Head: If you hear a ticking that doesn’t go away after retorquing, remove the header and inspect the gasket. A leak may be caused by a warped header flange—place a straight edge on the flange to check. If warped, the flange must be machined flat or replaced. Also check for debris between gasket and head.
  • Clearance Problems with the Steering Shaft or Frame: Long-tube headers often contact the steering shaft or frame near the collector. Solutions include loosening the engine mounts and rotating the engine slightly (using an engine hoist), dimpling the offending tube with a dimple die, or using a hammer and dolly on mild steel headers (avoid denting the tube more than 1/8 inch). For persistent contact, consider engine mount spacers or aftermarket tubular control arms.
  • Bolt Stripping or Breakage: If a header bolt strips the thread in the cylinder head, the head must be removed and a helicoil or time-sert installed. Always clean threads thoroughly and use a thread chaser before installation. Never install bolts that are too long; they can bottom out before clamping the header.
  • Increased Engine Noise: Headers can amplify valvetrain noise due to thinner metal and less sound deadening. This is normal, but if a knocking sound appears, check for a loose spark plug or exhaust hitting the chassis. Ensure all exhaust hangers are secure and the pipe has a slight clearance at all points.
  • Check Engine Light (CEL) Issues: If the CEL illuminates after installation, it is likely due to a downstream O2 sensor reading a leaner condition or a misfire code from a retuned air/fuel ratio. Scan for codes; if it’s a catalyst efficiency code, a spacer or defouler on the rear O2 sensor may be needed. However, proper tuning is the best fix.
  • Decreased Low-End Torque: Long-tube headers can shift the powerband higher, reducing low-RPM torque. If you experience sluggishness off idle, verify that the exhaust system is not overly large (e.g., 3-inch diameter on a stock 350) and consider a tune to adjust ignition timing. A performance torque converter (for automatics) or gear change can also compensate.

Post-Installation Break-In and Maintenance

After the initial heat cycle and retorque, drive the vehicle gently for the first 50–100 miles. Avoid prolonged full-throttle runs until the headers and gaskets have fully seated. Inspect all bolt connections and exhaust hangers after the first long drive. Over time, the header bolts may continue to loosen; check them at every oil change for the first 5,000 miles. Periodically inspect the header coating or wrap for damage; if wrapping gets oil-soaked, it can become a fire hazard. If you live in a region with road salt and snow, consider applying a corrosion inhibitor (like Fluid Film) to the exterior of coated headers to prevent rust.

Choosing the Right Headers for Your Vehicle

Not all headers are created equal, and picking the wrong design can lead to poor fitment and disappointing performance. Start by selecting headers specifically designed for your engine family and chassis—universal “fit-all” headers almost always require fabrication. Check for emissions compliance: shorty headers are typically CARB-approved and keep catalytic converters in the stock location, while long-tube headers are not street-legal in states that follow California standards. Evaluate the primary tube diameter: 1 5/8 inch is ideal for small-block street engines up to 350 horsepower; 1 3/4 inch suits 400+ horsepower; and 2-inch tubes are best for race-only applications. Collector size also matters—3-inch collectors are common for street/strip, while 3.5 or 4 inches are for high-horsepower builds. Finally, decide between mild steel and stainless: mild steel is cheaper and easier to weld but rusts; stainless is more durable but costly and harder to modify.

Conclusion

Installing Headman Headers is a rewarding upgrade that can transform your vehicle’s performance when done correctly. The key steps are proper preparation, meticulous surface cleaning, correct gasket selection, careful torque sequencing, and post-installation adjustments. Never skip the retorque step after the first heat cycle. By following the expanded procedures in this guide—including fitment checking, heat management, and performance tuning—you’ll ensure a leak-free installation that yields maximum horsepower and torque gains. If you encounter clearance or tuning challenges, consult a professional exhaust shop or engine tuner. With attention to detail, your Headman Headers will provide years of reliable service and a noticeable improvement in driving enjoyment.

For further reading on header selection and installation best practices, refer to resources like Summit Racing’s technical guides or MotorTrend’s how-to articles. Always verify torque specifications from the manufacturer’s instructions included with your specific Headman Headers.