The Seattle Mariners may have had a Parrott on the mound, but it was a night for the Birds at the Kingdome tonight. Ken Singleton and Eddie Murray slugged home runs and Mike Flanagan threw an eight-hitter to give the Baltimore Orioles a 5-2 victory.

The win, Baltimore's sixth over Seattle in seven games this season, insured first place for the Orioles through the All Star break which begins after Sunday's games.

"Yeah, but I still don't want to lose that game (Sunday)," said Oriole Manager Earl Weaver. "We may need it when we start up again.

"We may be coming out of the slump," added Weaver. The Orioles have lost seven of their last 11 games and seen their lead over Boston in the American League East trimmed to two games.

"I know it's tough to say you're in a slump when you're 27 games over .500, but we're starting to hit with power again and the pitching is beginning to pick up," Weaver said.

Flanagan, a 19-game winner for the Orioles last year, posted his 12th victory in 18 decisions. He has won his last six starts. the struck out nine.

"He has good stuff," noted Weaver. "He could have a better second half than first."

Flanagan said Ruppert Jones hit a high fast ball to spoil his shutout bid in the eighth. It was Jones' 18th homer of the year.

"When you're swinging good, that pitch's a mistake, and he's swinging good right now," said Flanagan.

The 27-year-old Oriole left-hander also gave up a run in the ninth. Mariner designated hitter Willie Horton led off with a single, went to third on Murray's throwing error and scored on a sacrifice fly by Bill Stein.

"I wasn't tired," Flanagan said. "It was my last start before the break, so I thought I might as well go all out."

Singleton gave the Orioles a 1-0 lead in the second with his 20th home run, over the 410-foot mark in center field. It equaled his 1978 home run total.

"It feels kind of good after last year to come back," Singleton said. "Last year I was recovering from surgery and my arm hurt all year. This year I feel 1,000 percent better and I think it's showing."

Singleton who will represent the Orioles on the American League All-Star team Tuesday at the Kingdome, said he's looking forward to the opportunity.

"You not only have the best hitters, but the best pitchers," he said. "Still, I guarantee there'll be some mistakes hit out of here."

Mariner starter Mike Parrott, who complied no record for the Orioles in three 1977 appearances before being traded to Seattle during the off-season, suffered the loss, his seventh in 13 decisions. Parrott allowed five runs on six hits and struck out nine.

One of the hits was Murray's two-run homer in the eighth.

"It was either a curve or a slider," said Murray, "that stayed up. He must have been getting tired, because earlier in the game he was keeping the ball down."