breather hoses

[cknight]

Greetings folks, if we are discussing the nipples and hoses that go from below the carburetors on the cylinder head to the air filters, these are not really breathers. Honda refers to them as air vents, and they are an early type of valve stem seal (which these engines do not have, in the modern sense). Through passages in the cylinder head, they connect to an annular groove and small hole at the mid-point of the intake valve guides. This creates a vacuum break, preventing the vacuum in the intake port from pulling oil down from the top of the valve guide. They are not directly exposed to crankcase pressure, or the intake system, other than via the approximate .0015 square inches of area between the ID of the valve guide, and the OD of the valve stem. You can cap these fittings, replace them with short 8mm bolts with sealing washers, or run a hose connecting them. Late engines did not utilize this system. You also need to cap the fittings that the hoses attach to on the air filters, as unfiltered air could enter the intake system through those open holes. If enough oil came through these hoses to soak the air filters, chances are your intake valves fell down into the cylinders. On most of these engines, there is a proper crankcase breather hose, usually connected to the cylinder head cover, that discharges inboard of the primary (engine) sprocket. For you early musclecar fans, the 1955-56 Pontiac V8 engines utilized this same intake valve "seal" configuration. Regards, Chase

[e3steve]

Good, informed info; thanks for the insight, Chase!