n the blackboard in the clubhouse, Earl Weaver has written, "In Uniform, 11:15. Hitting, 11:25. Infield, 1:15. Game Time, 2:05."

The blackboard has been scrubbed so the letters stand out white against it. Even Weaver's notorious printing is on its best behavior--neat and large.

As the season drags, his scribble will scrawl. By August, the manager will even forget to write on his board at all. But, for opening day, when Dennis Martinez faces Kansas City's Dennis Leonard here Monday, things must be just so.

The Orioles arrived home from spring training to a baseball world that was clean and, temporarily, perfect. White uniforms hung in each locker, fresh as unbroken promises. Mingled with the old names were such new or unexpected ones as Cal Ripken Jr., Dan Ford, Joe Nolan, Don Stanhouse, Floyd Rayford, Bob Bonner and Ross Grimsley. Like kids on the first day of school, the Orioles checked out their new locker assignments. Then, of course, they began swapping cubicles.

"I gotta put up with Stanhouse all year?" screamed Al Bumbry, seeing Stan the Man Unusual in the adjoining stall. "Put him back in his old corner," pleaded Bumbry, knowing nothing would please Stanhouse better than to return to the nook where he howled and laughed and plotted practical jokes in 1979.

"Well, we want you to be happy," said Stanhouse, dragging his gear to his corner where, within minutes, his gloves had been filled with shaving cream.

This was a clubhouse day for cutting ceremonial cakes and predicting team greatness. Opening day is for optimism. Asked what he liked best about his team, Weaver blithely and foolhardily answered, "Everything."

Indeed, it seemed that the cold, raw wind in Memorial Stadium today blew away all the Orioles' doubts about themselves.

It's axiomatic, of course, that a team be rosy-eyed while it's still undefeated. However, the Orioles seem delighted with themselves on season's eve. "It feels like spring of '79," said Ray Miller, the pitching coach, referring to Baltimore's last pennant-winning season. "Tell ya, it's all falling in place." Already, omens are being collected.

After their afternoon workout in frigid conditions, the Orioles learned that Martinez' wife had given birth to their third child, a seven-pound boy named Gilberto, at 2:10 p.m.

Weaver allowed as how Mrs. Martinez had timed it about right so that her husband the right-hander wouldn't have to be up all night worrying.

"Oh, I guess Dennis won't be too pumped up tomorrow," said Ken Singleton, grinning, as though pitying the Royals. "Be nice to pitch a no-hitter the day after your son was born."

Everywhere the Orioles looked, they saw a night-and-day difference from the strike-ruined season of 1981 that they loathed so much.

* "When we traded Doug DeCinces for Dan Ford," said infielder Rich Dauer, "we really got two 20-home-run men for one because it allowed us to put Cal Ripken (Jr.) in the lineup. Singleton and Murray will complement Ford and he'll help them, too. Ripken? He can't miss."

* "There's absolutely no reason I can't hit over 20 home runs this year," said Gary Roenicke, who appears to have an outfield job in hand now after rehabilitating a chronically injured wrist. Roenicke changed his pitch-him-on-the-fists stance, reacquired his pull-for-power stroke of '79 and reached base 31 times in 58 appearances (.534) this spring.

* "I think this club looks great," said pitcher Scott McGregor. "That's a real good-hitting lineup we're putting out there this year . . . I even think we'll make less base running mistakes this year because I don't think we can get any worse than we've been the last two years . . . Stanhouse and Grimsley were here (as castoff released players) just at the right time for us and for them. We've had two pitchers go on the disabled list (Steve Stone and Tim Stoddard) and Ross and Stanley can step right in. That's the kind of breaks we got in '79."

* Said pitcher Mike Flanagan, more soberly, "If everybody on the fence falls the right way, we'll be a great team. But if some of us (who have questions to answer) fall over backwards, it could be a little tough."

So, for one last day, Weaver could peruse his spring training stats and see batting averages such as these: Bonner (.404), Bumbry (.316), Ford (.292), Roenicke (.372), Lenn Sakata (.339). And fine ERAs from Stanhouse (0.75), Tippy Martinez (1.76), Sammy Stewart (1.91) and Jim Palmer (3.10).

Weaver could even dismiss an unbelievable, twice-normal 32 errors during a 14-12-1 spring as "Florida errors"--whatever they might be.

"Mr. (owner Ed) Williams is happy as hell that we signed Stanhouse and Grimsley (for the major league minimum of $35,000 each, as their former teams continue to pay guaranteed salaries)," said Weaver. "He says that disproves the old adage that there's no such thing as a free lunch."

For one more day, there's still a free lunch, and the promise of glory in every meaningless batting practice home run.

Sitting beside his locker, Singleton unpacked a dozen new bats. Each he marked with either two checks ("perfect weight, width of grain and handle taper"), one check ("good enough for a game") or no checks ("give 'em away").

Singleton's face glowed, as though he'd just seen a marvelous future augured in the tea leaves at the bottom of a cup.

"Five perfect bats out of 12. That's the most ever," he said to Jose Morales, as though only another hitter could grasp the meaning of such a thing. "Guess it's gonna be a good year."