On anything thicker than 3/16 base metal steel you should be able to get a nice clean bead with 1/8 70s2 filler at 130 amps. Tungsten 3/32 or 1/8. Argon 100% running about 20-25 cfh and any standard cup from 4-10.
Granted this is not enough amps for a full penetration weld without a bevel but more than enough to run good clean passes with 1/8 filler. Start there and if you don't like the way it looks post a picture up it may be a technique issue or metal quality.
