Pan World 250PS

[MGB]

I'm hooking up my return pump (Pan World 250 ps) which has a 1" threaded intake and output.
Here's the thing, I've tried a couple of schedule 40 adapters (female 1"/slip) and I can barely get over one full turn before its completely tight, that's without any teflon tape. While this might surfice, I'd feel a little more comfortable if I could get a couple of more turns on the fitting.
Anybody else had this problem with these pumps, I'm guessing its because these are imported pumps and the thread sizes arn't an exact match.

MGB

 

[lvreefer]

I didn't have any issues setting up mine. I have used both schedule 40 and 80. However these were for vinyl connections and not pvc. What about a 1" nipple connection then a slip x thread couple to your pvc, instead of a threaded coupler.