warm up regulator fittings

Hi, I'm trying to help a friend with a 79 928. I want to make a control pressure test tool but the WUR/control pressure regulator has a "compression" style fitting on it. Does anyone know what the size is and maybe where I can find a similar fitting? I believe Belmetric.com may have the fitting but don't know what size I need. Thanks

Rather than "making" a kit, I would highly suggest buying the CIS fuel injection test kit. It will have all of the fittings that you need and the gauge set it set up to appropriately test everything. I was able to source the kit and then added some of my own test parts to it when I was trying to do the testing myself without help. I can get the kit out and take some measurements of the parts needed if you still need them. By buying a kit, it will help with future issues. Common issues on the 77-79 cars are found more in the filter screens in the fuel distributor intake and in the ports to the individual injector lines at the fuel distributor. The screens will get plugged and cause all sorts of chaos with the system.