More information needed:
Those motors only need sufficient AC voltage to make them turn, as long as you are using a reasonable frequency (50Hz or 60Hz) they should work fine. However, what you can't control on them is the direction they rotate. You get a 50% chance of clockwise or anti-clockwise each time you turn them on so if your ball valve doesn't rotate continuously, you might just be driving it against the back-stop sometimes.
Unfortunately, with a two wire synchronous motor you can't easily control the direction it runs in. If you want to decide the direction you either have to use a motor with a phase winding or a reversible DC motor, in either case you wold still need a limit switch to turn them off when the valve has fully opened or closed.
Brian.