Yes, the air bleeds are used in the rotor housing as well. I don't think it
is an emissions issue directly. The earliest oil metering method was for the
metering pump to deliver oil to the float bowls of the carburetor. This
method was not optimum in terms of efficiency of oil useage, so they went to
the combination of rotor housing and intake manifold oil delivery. Reducing
oil metering is of course important for emissions, but the metering pump was
not capable of operating properly when the outlets were exposed to a vacuum.
Thus the invention of the air bleeds. BTW, Mazda calls them simply "bolts."
Also, we once measured the capability of the oil metering pump to deliver oil
against manifold pressure (turbo, supercharged engines), and found that the
pump delivery did not decrease against any reasonable (less than 15psi or so)
manifold pressure.

The air side of the air bleeds should be vented to atmosphere (via the air
filter of course). Casual examination of a throttle body would make it look
like the air bleeds vent to the downstream side of the throttle (in which
case the air bleeds would have absolutely no effect). But in actuality, there
is a convoluted passage in the throttle body that leads this bleed air back
out around the throttle plate.

Jon Lauter
Rotary Power Marine Corporation
www.rotarymarine.com

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