Can someone tell me why there is no seal between the injector body and the nozzle on the D47U? Does the nozzle just thread onto the body hand tight or do you use vice grips or something to tighten it down?
Hand tight is all that is required. Further sealing is achieved when assembled.
The seal is achieved when the assembly is completed because the nozzle and body are precision manufactured. Instructions say to hand tighten so that's what you should do. It doesn't mention vise-grips anywhere in that part of the reference