Dave, a calculator I found on the Web indicated that with oil going from a
3/8" dia (AN-6) through a 1/8" orifice would reduce the pressure by approx
40 psi.  So if your engine is putting out 70-80 psi that would bring it down
to the 30-40psi range which should be acceptable.

Ed

Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC