You mean the brass thingamajobby that goes into the hose betwixt the thermostat and the water pump?
Depends.
1/4"~ish for the hole in the middle of the end cap, but once the spring load opens up under pressure, (before t~stat opens), the opening is much larger as the whole end is a sort of relief valve affair that pushes back the end cap for a higher flow rate.
Pix can be found in the spider subsection FAQ, but I don't think actual dimensions are there other than length and width.
Depends.
1/4"~ish for the hole in the middle of the end cap, but once the spring load opens up under pressure, (before t~stat opens), the opening is much larger as the whole end is a sort of relief valve affair that pushes back the end cap for a higher flow rate.
Pix can be found in the spider subsection FAQ, but I don't think actual dimensions are there other than length and width.
