Once they quaked in their spikes when Frank Tanana took the mound. Lately they've been chortling.

The veteran left-handed pitcher, whose record was 1-7 after six straight losses with the Texas Rangers, marched into Memorial Stadium tonight and ignored the chuckles. He baffled the Orioles for nine innings with an array of off-speed pitches and a well-placed, moderately paced fast ball for a four-hit, 4-1 Ranger victory.

"In the old days if he threw like this he'd have had 14 strikeouts," said Oriole Ken Singleton, who went zero for three. "He was one of the best then."

But Tanana at age 28 has lost the zip that powered a 92 mile-per-hour fast ball in his prime. "He's had to learn how to adjust," said Singleton. "Tonight he did."

Tanana was so delighted with his 97-pitch, two-hour masterpiece before 10,469 at Memorial Stadium that he didn't know whose hand to shake first when it was over. "I'm just glad I found my way to the right dugout," he said with a laugh, then ordered his mates in the clubhouse to "hold it down. I'm trying to give an interview. I'm a little nervous. It's been awhile."

Tanana credited his success tonight to "good location on my fast ball, a better breaking ball and good off-speed stuff. The fast ball wasn't sizzling. But that's not me anymore.

"And," he added, "they gave me two runs early. I got two runs the whole month of May."

In fact, his mates scored only 12 runs in the previous seven games Tanana pitched as his miserable string drove to conclusion.

Tonight the struggling (15-29) Rangers jumped early on Baltimore starter Sammy Stewart. They took a 2-0 lead in the second inning as Stewart gave up a walk, then singles to Dave Hostetler, Larry Parrish and Mark Wagner. The first run scored when center fielder Gary Roenicke booted Parrish's one-hop liner, but the miscue became moot when Wagner sliced a single to right. The official scorer ruled both runs earned, on grounds they would have scored on Wagner's shot whether Roenicke erred or not.

In the fourth Hostetler made it 3-0 with a towering leadoff home run over the right-center wall near the 405-foot mark. And when Stewart yielded a double, a walk and John Grubb's RBI single to make it 4-0 in the fifth, Oriole Manager Earl Weaver called on rookie Storm Davis in relief.

Meantime, Tanana was having no trouble handling the Orioles. He allowed only one hit--Dan Ford's squibbed double under second baseman Doug Flynn's glove--through the first five innings.

In the sixth, Bobby Bonner, who replaced Lenn Sakata at shortstop after Sakata pulled a shoulder muscle, blooped another fluke double with two out. He scored the only Baltimore run as Rich Dauer and Ford followed with successive singles, the only two clean hits off Tanana all evening.

But with runners on first and second and Oriole strongman Eddie Murray at the plate, Tanana served up an off-speed pitch low and away and Murray dribbled it to first base to end the threat.

"Last week," said Tanana, who was a 6-0 loser to Stewart and the Orioles on May 27, "that ball would have gone foul and Murray would have cranked the next one out of here."