The Baltimore Oriole western swing losing streak grew tonight as Joe Rudi's grand slam home run capped a seven-run seventh inning as the California Angele romped, 10-1.

For Rudi, back in the lineup only two weels atrer a lengthy layoff because of a pulled hamstring, it was his 11th major league grand slam, one more than the Orioles' Lee May and tops among active American leaguers. It also was Rudihs first homer since May 8 - which was a bases-loaded shot off Boston's Chuck Rainey.

As they had in Friday night's 7-3 loss here, the Orioles tool an early lead, touching Angel starter Dave Frost for a run in the first inning.

Al Bumbry singled up the middle and, while Kiko Garoia was striking out, stole second and continued to third on catcher Brian Downing's throwing error. Ken Singleton brought Bumbry home with a sinle to lefe. After Eddie Murray struck out, Doug Decinces singled to right to put runners at the corners. But Terry Crowley bounced out to end the inning.

Baltimore starter Dennis Martinez gave up just two harmless singles in the first two stanzas, but in the third he got into trouble against the weakest hitters in Califronia's linup.

Former Oriole Larry Harlow, hitting .183, lined a double to center to open the rally after Joe Rudi had popped out. Then Jim Anderson, hitting .240 but nine for 20 the last six games, bloped a single to right that chased Harlow bhome to tie the game. Bert Campaneris, a .190 hitter, singled to put runners at first and third.

Martinez stemmed the tide momentarily, slipping a called third strike past Bobby Grich, but then walked Dan Ford to load the bases for Don Bayor, who had hit two home runs Friday night.

"When he's in a streak like this, you have to make perfect pitches and throw a pitch he isn't expecting," Oriole manager Earl Weaver said of Baylor before the game. Even that was not enough this time.

Martinez made tow perfect pitches to get the count in his favor at 2-0. Then he fooled Baylor with a pitch and the Angel's off balance designated hitter bounced toward htird. When DeCinces came up with the ball he had no play, for Baylor was crossing first and Anderson was stepping on home with the second run of the inning.

Martinez had enough left to get Willie Aikens on a ground ball, but in the fourth he was in trouble again, thanks to a walk to Downing and Harlow's single to left that enable Dowing to go to third when Gary Roenicke was slow getting to the ball.

Anderson batted in his second run moments later, dropping a perfect bunt in front of the plate as Downing raced down the line from third. Harlow wound up at second, and when Campaneris laced his third single of the night up the middle it looked like another Angel run, but the ball struck the heel of Harlow's left foot and he was called out for interference.

Ffrost, meanwhile, was breezing along after his shaky start. The 6-foot-5 right -hander retired 12 men in a row until Dave Skaggs doubled with two out in the fifth. Then he got Bumbry on an infield bouncer to end that mild threat.

Baltimore authored another mild threat in the sixth, when Garcia singled and stole second as Singleton was striking out. But Frost struck out Murray fro the third time and Crowley fouled out to downing.

The Orioles came apart in the bottom of the seventh The inning started casually enough, with Campaneris legging out a roller down the thrid base line for his fourth single. Then Grich tripled into right-center.

Ford bounced out, but when Martinez walked Balor on four pitches Weaver had seen enough. He summoned left-hander Mike Flanagan from the bullpen to face the left-handed hitting Aikens. The manager must immediately have regretted decision, for Aikens bounced a double down the right field line.

So Flanagan, making his first relief appearance of the yeart, was ordered to walk Downing and set up a confrontation between Don Stanhouse and Rudi.

Rudi won that battle by lining Stanhouse's 2-1 offering into the left field seats for a 9-1 lead.