Valve Train

What Is the Valve Train and Why Does It Matter?

The valve train is one of the most critical systems in any internal combustion engine. At its core, it controls the precise timing and movement of the intake and exhaust valves, governing how fuel and air enter the combustion chamber and how spent gases exit. The camshaft is the heart of this system — its lobes push against lifters, pushrods, rocker arms, and ultimately the valves themselves, all in carefully timed sequence with the crankshaft and pistons.

As engine designers noted long ago, the ultimate objective of the camshaft function is to "trap" the greatest possible weight of fuel/air mixture in the cylinders to attain maximum volumetric efficiency. Every component in the valve train — from the camshaft profile down to the valve springs and retainers — plays a role in achieving that goal. For street drivers, a well-maintained valve train means reliable idle quality, smooth power delivery, and long engine life. For performance enthusiasts and racers, optimizing the valve train is one of the most direct paths to more horsepower and better response across the RPM range.

Key Valve Train Components

• Camshafts — Define valve lift, duration, and timing. Cam selection is the single biggest factor in shaping an engine's power curve.
• Lifters (Tappets) — Transfer motion from cam lobes to pushrods or rocker arms. Available in flat-tappet and roller designs, hydraulic and mechanical.
• Valve Springs — Keep valves firmly seated and ensure they follow the cam profile accurately, especially at high RPM where valve float becomes a concern.
• Pushrods — Transmit motion from the lifters to the rocker arms in OHV engines. Length and rigidity matter significantly at high engine speeds.
• Rocker Arms & Retainers — Convert the upward pushrod motion into valve-opening force and secure the spring assembly to the valve stem.

Shopping for Valve Train Components: What to Consider

Choosing the right valve train parts starts with understanding your application — street cruiser, weekend warrior, oval track racer, or full-on drag car all have very different needs. Cam duration and lift must be matched to your intended RPM range, cylinder head flow, and induction setup. Valve springs must be rated appropriately for the cam's lift and your engine's redline; undersized springs lead to valve float while oversized springs accelerate wear. Always verify that lifter type (hydraulic vs. mechanical, flat-tappet vs. roller) is compatible with your chosen camshaft, and ensure pushrods are the correct length for your geometry.

Top Valve Train Brands

Isky Racing Cams is one of the most storied names in performance engine building. Founded by the legendary Ed "Isky" Iskenderian, the company is recognized as the world's largest racing, performance, and economy cam manufacturer, producing camshafts, lifters, and a wide range of high-performance valve train components. Isky maintains a continuous dynamometer testing program to validate every product, covering applications from grassroots hot rods to professional drag racing and land speed record attempts.

Howards Cams has been synonymous with high-performance camshafts since its founding in 1945, and a great number of valve train innovations can be traced back to the brand. Howards pioneered the use of real on-track experience to guide camshaft design, fielding their own Top Fuel test cars and supporting racers across circle track, drag racing, road racing, and marine disciplines. Their American-made lineup extends well beyond camshafts to include rocker arms, valve springs, retainers, and lifters — including their innovative Direct Lube flat-tappet lifters.

Skunk2 Racing brings a sport-compact focus to the valve train space, with a deep catalog of components engineered specifically for Honda and Acura VTEC engines. Since 1994, Skunk2 has designed, developed, and tested its entire valvetrain lineup in-house, producing products validated on everything from street cars to 11,000 RPM drag racing engines and high-revving superbikes. Their Pro Series and Alpha Series valve springs, titanium retainers, and Alpha Series valves are purpose-built for high-lift camshaft applications and extended high-RPM use.