"Grand slam, grand slam," chanted the Baltimore Orioles in the ninth-inning silence of County Stadium tonight as Eddie Murray strode to the plate.

"How long since we had a slam?" screamed veteran Bird Mark Belanger. "Have we had one yet this week?"

"Don't let 'em do this to you," bellowed a dozen Birds, led by rookie pitcher Sammy Stewart. "Are you gonna let 'em give somebody an intentional pass to get to you?"

The Milwaukee Brewers stared at the Orioles in disbelief, just as they have for two nights. Are these Birds crazy?

On the first pitch, Murray demolished a Reggie Cleveland fast ball, driving it 450 feet into the right field bleachers for Baltimore's fourth grand slam homer in eight days.

That slam, giving the Birds a safe 9-4 lead, was the crowning blow of a magnificent 9-5 Baltimore victory that pushed the now seriously worried Brewers 8 1/2 games behind in third place.

"What does this mean?" said Ken Singleton, who moved into the AL home run lead with his 26th tonight. "It means we're gonna win it all. Nobody's going to catch us. But then, I've known that for a long time."

Ecstatic is the only word for the 71-34 Oorioles, who have won 12 of 14 oon the latest tear of what Manager Earl Weaver calls "105 games of baseball so fundamentally souund that it can no longer be called 'a streak.'"

Word arrived before the game tonight tthat the Boston Red Sox had blown a five-run ninth-inning lead and lost, 11-10, in the 11th inning of a doubleheader opener at Cleveland. When the Indians completed a sweep with a 3-0 victory in the second game, the Oriole lead had ballooned to 7 1/2 games.

"Carl Yastrzemski, do your worst," chortled Weaver as he shaved after the victory. "Jim Rice, hit all the homers you want. What are you gonna do if we don't lose?"

That is the mounting problem of both the Bosox and Brewers, who wonder on what food these supposedly puny Orioles feed. Baltimore is winning at a 110-victory pace.

"We were just going stone nuts in the dugout tonight," said Stewart, the winner tonight who must think he has died and gone to heaven to pitch for this club. "Nobody can know what it feels like in our dugout."

Tonight, Stewart pitched 6 1/3 innings of three-hit relief for Mike Flanagan that was a textbook sample of poise and challenge-'em pitching.

"That country boy amazes me," said Ray Miller, Oriole pitching coach. "I've coached him every step from his first day in the minors and I s.till can't believe him.

"When he's on the mound, there's no quit in him. He just glares down at the best-hitting team in baseball as if to say, 'Okay, boys, let's go. Let's get it on. I'm comin' to get ya.'"

The Orioles have been coming to get the Brewers from the instant they stepped into town. As the O's begin every game, Singleton yells as Al Bumbry gets in the box, "Let's go, little boomer."

Then the entire Oriole team gives a locomotive chant: "Oooooh, aaaaaah."

"When we did it Monday night," Singleton said, "Sal Bando jumped straight up in the air."

The Brewers played like an unnerved, overmatched team tonight, even with 36,105 of their own fans begging for victory.

The Brewers allowed 15 Oriole hits, including four by Rich Dauer. They also had three errors. That didn't count the ground ball "hit" off the second baseman's chest. Or the fly ball that bounced out of a glove at the wall for a double. Or the passed ball. It didn't even count the extra bases allowed by a collection of Brewer left fielders.

In the fifth through eighth innings, with the Birds holding a 5-4 lead behind Stewart, they put seven runners on base and stranded them all.

"It looked like we were waiting to fill the bases so we could get the maximum possible number on one swing," Dauer said.

Finally, in the ninth, the Brewer dam broke. A grounder to second by Bumbry and a fly to left by Dauer that should have produced two outs instead produced a tainted single and double.

With Singleton and Murray - back-to back switch hitter - coming up, Brewer Manager George Bamberger had no way to play percentages.

"His hands were tied," Weaver said, a grin growing. "You could say we had him caught in the switches."

When Singleton was passed, Murray had his chance to join Pat Kelly, John Lowenstein and Lee May on the recent grand slam team.

"I'd stranded men on second and third in the seventh and the guys were teasing me," Murray said. "They were saying, 'When are you going to knock somebody in, cleanup man?' When I nit it, I thought, 'Well, I finally got somebody home.'"

Right fielder Sixto Lezcano never budged for what was by far the longest homer of the game's six.

"I don't think," Murray said, "that he really needed to move, you dig?"

"Earl's No. I son -Eddie Murray - strikes again," said Singleton, whose homer was his 11th of the year and 32nd of his career when Mike Flanagan (the starter) was on the mound.

The Orioles claim they believe all this magic is their due. Who says grand slams on demand can't last forever? Who says the final two months start Wednesday?