Hi Steve, the 13B sump breather is almost irrelevant. It is connected to the oil pan which is totally sealed from the engine block - other than the air expansion from hot oil Vs cold oil there is no excessive pressure build up going on ... For my original setup, I drilled a 5/16 hole in the oil filler cap and left the 1/4 inch return line connection open. Never saw any sign of oil spray coming out of either - -.  Now I have increased the 1/4 inch return to 3/8 and connected it to my redrive as a breather/secondary oil return ... So whatever that "breather" was doing it is now very restricted with no ill effects ....  Jeff  
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-----Original Message-----
From: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sender: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Date: Sun, 01 Nov 2020 06:00:50
To: Rotary motors in aircraft<flyrotary@lancaironline.net>
Subject: flyrotary Digest #5031

        Rotary motors in aircraft Digest #5031

 1) Sump Breather?
    by "Stephen Izett stephen.izett@gmail.com" <flyrotary@lancaironline.net>

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