I want to convert my nb to a return fuel system but I'm a bit lost on what this thread size is on this fitting. I can't find the size and tbh im unsure of what other adapter I need to make it work with 6an ptfe hose. Can anyone help me out with tue fittings I need? I already have my eyes on a kit for 6an ptfe hose and fittings but I'm pretty sure I need something else to connect a line to this adapter then over to my afpr.

 

I believe I have figured this out but if anyone still wants to share I'm open to it

 

They’re typically 1/4 or 1/8npt, looks like a summit description says 1/8npt.

 

Yup I ended up finding it was 1/8 npt. So I ordered a 6an to 1/8 npt and for the return line on my nb im just going to use ptfe line since I will probably nit be going back to pump gas. Eventually I'd like to replace the entire setup with ptfe or gates barricade but for now all the lines currently should hold up with e85.