Feuling Billet Rocker Box & Cylinder Head Breather Kit for Harley Twin Cam & M8

Upgrade your engine's ventilation system with these high-performance billet rocker box and cylinder head breathers. Designed to replace problematic factory plastic breathers that are prone to heat distortion and cracking, these kits provide a superior seal and optimized engine breathing for both Twin Cam and Milwaukee Eight engines.

Each breather is precision-machined from 6061 billet aluminum with square surfaces to promote excellent gasket and umbrella valve sealing. The unique design maximizes breather volume and features properly sized inlets and locations for optimum performance. For enhanced reliability, the system utilizes multiple drain ports located on the inside floor; these ports are chamfered on the ID to allow for easy drainage while remaining squared off on the exits to deter filling from splash oil.

Key features and benefits include:

• Machined from 6061 billet aluminum for maximum durability.
• Optimized breather hole sizing for superior engine ventilation.
• Square surfaces and high-quality O-rings ensure a leak-free system.
• Advanced internal drainage system to prevent oil carry-over.
• Designed to help maintain engine vacuum for peak performance.
• Easy serviceability and stock replacement fitment.

These kits are versatile and can be used with external venting via the dipstick, transmission cover, and air cleaner. Testing on healthy engines has shown significant improvements in oil management and vacuum retention compared to OEM components.

Kits include: billet breather housings, breather filter elements, umbrella valves, and high-quality hardware (including ARP hardware where applicable).

Rebuild Kit Twin Cam Billet Breathers

Fits Feuling® and OEM Twin Cam rocker box breathers

• Made in the USA
• Kit includes:
• Two Umbrella valves
• Two Filters
• Four Gaskets

Rebuild Kit M8 Billet Breathers

• Kit includes:
• Two Umbrella valves
• Two Filters
• Four O-Rings

MADE IN THE USA

WARRANTY: Includes a 1-year warranty with an option for an additional year if the warranty form is completed on the manufacturer's website.

Note: Rocker cover gaskets are purchased separately. Proper installation ensures a sealed engine environment, preventing common issues like broken exit nipples and material distortion caused by excessive heat.

1999-2016 Harley-Davidson Touring Twin Cam

1999-2017 Harley-Davidson Softail & Dyna Twin Cam