Exhaust Valves

How Do Exhaust Valves Work?

Exhaust valves open to release burnt gases from the cylinder after combustion, then close to seal the chamber for the next intake and power stroke. A lobe on the camshaft lifts the valve through the lifter, pushrod, and rocker arm, and the valve spring closes it again so the face seats against the cylinder head. Because they sit in the path of gases that run far hotter than the intake side, exhaust valves heat up and wear faster than their intake counterparts. They're also smaller than intake valves, since the outgoing exhaust is under pressure and doesn't need as large an opening to escape. If you're replacing exhaust valves, it's worth inspecting the matching intake valves and the rest of the valvetrain at the same time so the whole cylinder head seals correctly.

What Are Exhaust Valves Made Of?

Exhaust valve material determines how much heat and stress the valve can take before it burns or distorts, so match it to how hard your engine works:

• Stainless steel: the most common performance choice, with strong heat resistance and durability for street and naturally aspirated builds.
• Titanium: much lighter than steel, which cuts valvetrain weight and helps high-RPM engines, and is usually reserved for race applications.
• Inconel and other superalloys: built for the highest exhaust gas temperatures found in turbocharged, supercharged, and endurance engines.
• OEM-style alloys: nichrome, nickel, and silicon-chromium valves used for stock replacements where factory specs are the goal.

Stock-replacement specialists like Enginetech cover these factory-style alloys for a wide range of engines. For a refresher on how valves fit into the head, read our guide on what a cylinder head is.

What Are the Benefits of Performance Exhaust Valves?

Upgrading to performance exhaust valves improves both power and durability over worn or stock-style valves. Precision-machined faces and back-cut designs increase airflow when the valve is open and improve sealing when it's closed, so more combustion pressure pushes the piston instead of leaking past the seat. Tougher materials such as stainless steel and titanium also resist the heat and pounding that burn or bend lesser valves, which extends service life between rebuilds. Brands like Manley and Edelbrock machine their valves with swirl-polished heads and hardened tips for consistent flow and reduced guide wear. To get the most from the upgrade, plan to match new valves to your cylinder head's seat angles and spring package rather than swapping them in isolation. That way the added flow and strength actually show up as measurable power on your street or race engine.

How Do I Choose the Right Exhaust Valve?

Choosing the right exhaust valve comes down to matching head diameter, stem diameter, overall length, and valve style to your specific cylinder head. Start with your engine family - small-block Chevy, big-block Chevy, small-block Ford, or a late-model import - since head and stem sizes vary between them. Dart offers valves sized for its own performance heads, while Melling covers many stock-replacement sizes for domestic and import engines.

• Confirm head and stem diameter against your head's specs before ordering.
• Decide between single valves for a targeted repair and full sets for a rebuild.
• Match valve material to how hard the engine works.

Browse the full cylinder head components selection, step up to complete cylinder heads if you're starting a fresh build, and check our guide on how to clean cylinder heads before reassembly.