PCV crankcase breather cannister

Chrome. Positive Crankcase Ventilation, a universal chrome plated steel crankvent system for use on all H-D models. Fits regular 3/8" oil lines. The engine can breath out, but not breath in, thus maintaining vacuum in the crankcase at all RPM for improved performance. Note: Primarily designed for bottom vent and custom head vent applications. Can not be used in regular head vent applications due to space required. Tech tip: How active crank vents work. On the down stroke of the pistons the air in the crankcase is compressed. H-D engines, either bottom or head vent models, are not able to vent the required volume. With large displacement engines this problem increases even more. All crank vents let the pressure escape, but also partially allow it to return when the pistons go up. In an active crank vent (crankcase breather) a valve closes, preventing gasses to re-enter the crankcase, creating a stronger partial vacuum inside the crankcase. This can increase horsepower, depending on the engine. Less problems will occur with blown or weeping gaskets and piston compression rings will seal better.