Is there any advantage to moving to the new arc barb-spouts if you are on a gravity system? I do believe this spout was designed with vacuum in mind but we are on 5/16 drops into buckets. My initial thought would be maybe more sap since the spout barrel is shorter upon looking at some information (see the link below and click on "more information' under the 5/16" arc barb-spout).

https://middlevalleymaple.com/services/