Two-run homers by Rick Dempsey, Eddie Murray and Floyd Rayford led the Baltimore Orioles to an 8-5 victory over California tonight as Scott McGregor won his 12th straight over the Angels.

The Angels have lost six straight games while scoring only 10 runs.

Ken Singleton finished with two doubles and a single and drove in the other two Baltimore runs.

McGregor, who has not lost to the Angels since Aug. 18, 1978, went 8 1/3 innings in improving to 9-6.

After giving up a home run by Doug DeCinces in the second inning, McGregor had little trouble until the ninth, when Reggie Jackson opened with a home run. When Fred Lynn hit a two-run homer one out later, McGregor was replaced by Don Stanhouse.

Stanhouse gave up two singles and was replaced by Tim Stoddard. He yielded an RBI single to Brian Downing before Tippy Martinez relieved and got the final two outs.

The Orioles got to loser Ken Forsch (7-7) for six runs on eight hits in 4 2/3 innings. Baltimore started quickly as Al Bumbry opened with an infield single, took third on Rich Dauer's single to right and scored on Singleton's double to right.

Gary Roenicke opened the second with a walk and Dempsey hit his fifth homer of the year, over the 404-foot mark in center. Murray hit his 12th homer of the year in a three-run fifth, and Rayford homered off Luis Sanchez after Dempsey singled to open the eighth.