Hobbsy: Since the pressure on the downstream side of a flow restrictor is less than the pressure upstream, the tendency to "suck air" is greater on the carb side of the needle assy. I just thought that the thing should be hooked up so that the threads were on the high pressure side and not on the "suck" side. Since you tried it both ways successfully, then the answer is: "JUST HOOK THE DAMN THING UP ANY WAY YOU WANT AND GO FLYING FOR CRISSAKES!" Thanks for the help.