Hi -
Thanks for answering. Sorry about the lack of info. The new Monark injector nozzles are fit into my existing Bosch injector housings. My engine is about a 1958 model with the brass "banjo" fittings for the return lines. (Not the newer method of return lines through rubber hoses). I don't see any leakage from the body of my housings. When I fit the new nozzles into the injector housings, I was pretty careful about cleaning everything.
I suspect that the steel heat shields or (some call them seal rings) did not compress when installed causing leaking. What do you think? Thanks Angus