Lloyd Moseby hit a three-run homer in a seven-run fourth inning yesterday to help the host Toronto Blue Jays to a 12-4 rout of the Minnesota Twins.

It was the Twins' eighth loss in 10 games. They have lost 10 of 11 games to the Blue Jays this season, including five in the last nine days. Toronto has won eight of 10.

Dennis Lamp, making only his second start of the season, went 5 2/3 innings and allowed four runs on seven hits in bringing his record to 7-7. Roy Lee Jackson pitched 3 1/3 innings to earn his ninth save.

Trailing, 1-0, after Kent Hrbek's third-inning RBI single, the Blue Jays got to Mike Smithson (13-11) in the fourth. A leadoff walk to Willie Upshaw and singles by George Bell and Rance Mulliniks tied the score. The runners advanced on a ground out and Ernie Whitt was intentionally walked to load the bases. With two out, Damaso Garcia hit a single to make it 3-1.

Dave Collins followed with an RBI single, moving Garcia to third. Collins then stole his 49th base and Moseby followed with his 18th homer, a shot inside the right-field foul pole, to give the Blue Jays a 7-1 lead.

The Twins got three runs in the sixth, one coming in on a bases-loaded walk to Tim Teufel and two more scoring on a single by pinch hitter Darrell Brown.