The Gen II incorporates a dual breather system for use on Evo, Twin Cam or Sporty.

Part of the design criteria was that the rocker box achieve our aesthetic goals but also sacrifice nothing in engine performance or reliability. To that end,  the Racedyne rocker box has several advantages.

Additional cooling fin surface area and air flow were added to help cool the heads and oil that end up in the rocker box. A very simple but highly effective scavenging check valve ensures optimum pressure evacuation and uses the stock external breather hardware. Special consideration was given to ensure that the sealing areas do not leak over time and all aluminum components are hard anodized for longevity.

The rocker box is made from billet 6061 T6 aluminum. This is much stronger than cast pieces ensuring reliable use for performance engines.