Orioles Ken Singleton and Lee May combined for nien RBI to lead Baltimore to a 12-1 win over Seattle tonight at Memorial Stadium.

Steve Stone (8-7) was the benefactor of the offensive explosion, improving his home record to 7-1 by scattering five hits in his third complete game.

Singleton's five runs driven in and May's bases-loaded home run - the third Oriole grand slam in five games - gave the team a much-needed boost before departing for a 10-game road trip to face the world champion New York Yankees, West Division defending champion Kansas City and the Milwaukee Brewers.

The 17,475 fans almost witnessed the breaking of an obscure league record as the Orioles scored nine runs in the fourth inning after two were out and nobody was on base.

The record is 10, set by the Chicago White Sox in 1959. The Orioles already have had a bigger inning this season, against Oakland when they tallied 10 runs in the seventh inning April 29.

The Orioles bombarded two Mariner pitchers for nine runs and seven hits in the fourth inning, all after two were out. May's 11th career grand slam, a tremendous poke 30 rows deep in the left-field bleachers, capped the fireworks.

"I went up to the plate looking for the home run," May said. "Every time you look around we've got the bases laoded so somebody is going to have a chance for a grand slam. We already had a seven-run lead so I had only one thing in mind."

The inning started innocently enough when Doug DeCinces popped up and May struck out. But then Rich Dauer and Rick Dempsey doubled back to back, scoring Dauer, who had missed the last two games with a knee injury.

After intentionally passing Al Bumbry, Seattle starter Randy Stein was lifted for John Montague, who faced six batters. All six reached base.

Kiko Garcia singled in a run, Singleton singled in two and John Lowenstein ripped a hit to left scoring a run. DeCinces walked, loading the bases to set the stage for May, who left the on-deck circle with home run on his mind.

His blast only increased the healthy lead Singleton had given the Orioles with his three-run opposite-field home run. It was Singleton's 24th of the season, matching his career high in 1977. Singleton has hit in 12 straight games.