Unlike Sylvester Stallone, who seems a larger specimen on the screen than he is in person, Carl Weathers looks imposing in three dimensions.

At 6 feet 2 and a muscular 205, there's no incongruity between his crunching, big-pawed handshake and deep, commanding voice and his screen impersonation of black heavyweight champion Apollo Creed in "Rocky" and the newly released "Rocky II."

Weathers is on the edge of what could become a major starring career. He has gained much along the 31-year trail from New Orleans, where he was born, to the San Fernando Valley, where he now lives with his wife, Mary Ann, and their two sons (Matthew Brandon, 3, and Jason Anthony, 4 months). And in Washington last week, he showed that he has acquired a grandiloquent streak of positive-thinking oratory:

"I'm looking for a Picassoesque role, something that will throw me into new period. I feel Apollo Creed has taken me so far, but now it's necessary to go beyong that. It's as if I were coming out of my Blue Period.

"I want to go from wools to silks for a change, from dark browns most of the time. I'm ready to try a little cream or cafe au lait.

"I'm looking for something celebral that you'll also be able to relate to emotionally. Or something visceral that you'll be able to relate to intellectually. Something that has meaning at all levels."

The oldest of three children born to a day laborer and his wife, Weathers recalls New Orleans as "a heavy-duty city when I was a kid. That was still the Deep South when I was growing up, and we were in the bowels of the city. I wasn't a fighter by nature. I held it all inside. It was not a happy time. In fact, when I'm feeling sorry for myself, I remember it as a perfectly miserable time. I think I was consciously trying to escape from a very early age.

"In the streets they'll kill you, literally. It was my curse to be a sensitive kid. Certain things I was drawn to - like doing a little acting or singing in the choir - had no credibility on the street. And I was too ignorant and intimated to try to explain why they seemed valuable to me. The other guys would say, 'What is this, man?' and all I could was mumble.

"I didn't get an active desire to play along with the peer group pressure, to be macho machismo, until I got in the eight grade and woke up to the fact that only the guys in sports seemed to attract the good-looking girls. That's how I got my first girl, by going out for football.

"It didn't last long. I was still so dumb that I didn't realize you were supposed to take things further than hanging out together at school. They expected to be called up and asked out! It had never occured to me that the business was that complicated, and it cost me my first girl almost as quickly as I got her."

Weathers was impressive enough as an eighth-grade football player to earn a scholarship to St. Augustine, a prestigious Catholic high school for black male students. "If you were a black kid in New Orleans," Weathers said, "it seemed like an overwhelming privilege and opportunity. For me it was as awesome as going into outer space."

Despite his attachment to the school, Weathers moved to California after his junior year following a vacation spent with his grandmother, who lived in Long Beach.

"I was knocked out by California. "The parks! I'd never seen anything like the parks they had. There were all these kids, they had all different colors. You could check out a game, or a ball, and they'd actually trust you to return it after you were through. It was green and sunny and I was just one of the kids.

"All of a sudden I was in a place where black kids and white kids sat together and played ball together. It was like some kind of fantasyland."

Weathers attended Long Beach City College for a year before transferring to San Diego State on a football scholarship. "I finally thought I was a jock," he said, "and owed myself a shot at pro ball.At the same time I didn't want to study the things you had to if you wanted to be a P.E. major.

"So I found myself thinking of the theater arts department. I started doing a few small things in class and discovered I had a proficiency for it. My reading was awful, but I got a walk-on in 'A View from the Bridge.' For the rest of school I kept on cultivating football on one hand and acting on the other."

A defensive end in college, Weathers went undrafted but won a spot on the Oakland Raiders in 1970 after trying out as a free agent. Switched to linebacker (at his own request, he maintains), Weathers spent five seasons in pro ball with Oakland, the B. C. Lions of the Canadian League and, finally, the Detroit Lions.

"I was good enough to fool 'em, but never dedicated enough to become a great player," Weathers said. "Up to a point everybody can capitalize on the fact that nobody knows what's goin' on. I could make coaches believe I could do what they wanted me to do, but that's not the same as pushing yourself. The great ones are willing to work harder.

"I was still looking to hop out of football as soon as I made some headway with acting. I forced the issue by exaggerating a little. In L.A. I lied about having acting credits up in San Francisco. How can they bother to verify your claim that you studied at ACT (the American Conservatory Theater) or worked as an extra in 'Dirty Harry'?

"They can't. But if you run scared, you'll never get what you want. Naturally, you've gotta be prepared to deliver at some point. Actors do it all the time: Sure I've played that, sure I can do that. At least it can get the opportunity to prove that you can't.

"By discreetly stretching things, I got an agent and then a dramatic coach and then the chance to audition for a real part. One thing led to another. After finally getting that first commercial, I held out for commercial assignments in which I'd be prominently featured. The same thing with bit roles and supporting parts."

Weathers appeared as an extra in "The Candidate," whose director, Michael Ritchie, later cast him in a prominent supporting role in "Semi-Tough." Weathers' first significant role in a theatrical feature came in the 1974 black exploitation melodrama "Bucktown." Finally the Oscar-winning "Rocky" brought him a vast public.

Black moviegoers may have reacted negatively to the character of Apollo Creed, who functions in "Rocky II" as a stock villain in certain respects. But Weathers did everything in his power to make Creed forceful and believable, and Stallone was willing to accomodate any objections he had.

"There's no 40 acres and a mule," he declares authoritatively. "Everybody pays his dues, does what he can with what's available. Maybe there will be some cause for resentment, some kind of backlash, but that's totally out of my control and has no bearing on my performance. I simply say, take it in its proper perspective, which may not be an altogether realistic perspective.

"God knows I don't have it all together, but I've learned that not doing what you want to do will limit the success you can have. I like to think old John Wayne knew that. He had his ups and downs, but there was a full life, a real career. He didn't have to sign out full of regrets.

"I'd rather die and go to hell right now than live and end up staring in the mirror someday and saying, 'Were you ever full of . . . ! You blew it, man!" CAPTION: Picture, Carl Weathers, by Gerald Martineau