O.D. of orings on injectors measure .620 upper and .650 lower.
What about tapping the ports for NPT threads? As a kit, consumer could assemble themselves easily, with you doing the machining ;p Not sure if there would be enough material to tap them for threads to properly seat with adequate engagement. Just a thought. I would love to see metal (steel, aluminum or brass) return caps made available to the IDI community. I know I'd save up for a set
brass can be TIG welded
brass can be TIG welded
whenever I get around to making mine, I have some tapered springs that will be installed on top of mine to seat between the cap and injector line nut to keep it seated solidly