Arnold Schwarzenegger, seven-time Mr. Olympia, five-time Mr. Universe, once Mr. World, master at posing and promoting, is a muscle man in search of a new image. Often, he walks down Fifth Avenue and stops strangers.

"I do tests," he says, Austrian accent thick, booming voice confident. "I say to 10 people, 'What do you know me for?' and people will say, 'I know you from "Wide World of Sports"--Mr. Olympia.' I say, 'Anything else?' and they say no. Then I go to the next guy . . . and he says, 'You're the body-building champion.' I hear this 10 times in 1975. Then two years later, I go again and one person says 'I saw you in a movie' and another says 'You wrote a book.' Then it's eight to two. It's not accurate information, but somehow I always know where I'm at . . ."

The tide is turning. A few months ago he discovered he had made progress on Fifth Avenue. Six people recognized only his muscles, but four knew his movies, too. His latest movie, "Conan the Barbarian"--which opens on Friday--will surely tilt the odds. He's sure of it.

Pretty soon, everyone on Fifth Avenue will realize that Arnold the Body Builder has become Arnold the Actor.

"I was sick and tired of winning," he says nonchalantly. He shrugs the familiar massive shoulders. "Where's the challenge after 13 world championships? The spice was gone. I wanted to take risks."

Schwarzenegger was in Washington to push "Conan," a blood-drenched fantasy crammed with risk, sex, violence and spice. There are snakes, vicious wolves, rolling heads. Schwarzenegger is Conan. For all his barbarics, Conan is cute in a medieval sort of way. Strong, but sensitive. Charming but crafty. And tenacious. Not unlike Schwarzenegger.

Arnold Schwarzenegger is 34 now, no longer the hungry young man who came here from Austria looking for fame nearly 15 years ago. There are traces of gray in his light brown hair, and tiny wrinkles around his green eyes. He has dated Maria Shriver, of the Kennedy clan, for four years, and there are persistent rumors of marriage, although Schwarzenegger denies them.

Sitting in the conference room of a local television station, where he has just finished an interview, Schwarzenegger is a combination of collegiate casual and Brooks Brothers' best. A Navy blazer, crisp beige cords, a pink cotton shirt--all custom made to fit the 6-foot-2, 216-pound frame.

Yet, as his animated conversation progresses, he leans back and the cloth strains, leaving gaps between the buttons. "It's a problem," he says sheepishly. "Getting the clothes to fit." He rolls up the long sleeves, folds the large hands, and he's ready.

How does a body builder with bulging biceps and thunderous thighs propel himself into a new career?

Any way he wants to.

"A photographer is here?" he asks the press agent for Universal, which is distributing the movie. "I said no photographs."

"I didn't know," whispers the agent.

"Don't you photograph well?" he is asked.

"Oh, no. I take good pictures," he smiles, "but the newspapers, they always pick the worst ones." He relents. It's good for the story.

Arnold Schwarzenegger, by his own admission, is a tireless self-promoter.

"I had to be," he says.. "When I came to this country nobody knew there were body building men. I wanted to create a business in body building and I felt you first had to popularize the sport. The important thing is that you first do some service for the people and turn them on to health and fitness and at the same time you can profit from it.

"And that is the case with acting," he says. "I knew I couldn't rely on anyone to create myself as an actor--that I have to work on strategy like I did with body building and create a need for me in acting. I develop a plan and promote myself as the actor. I do all the things that are necessary."

Schwarzenegger believes in this movie. He has even signed an option for a sequel. He thinks it's the "best job" he's done and he's pushing--a call to Johnny Carson to remind him to introduce Schwarzenegger as "an award-winning actor--not body builder;" notes asking for help to all the reporters who interviewed him as a body builder. A Boston Globe reporter flew to Washington to interview him at Schwarzenegger's request. He calls photographers and reprimands them when his picture doesn't turn out quite right. And he pushes Universal, touring three or four times the number of cities they had planned.

Well over a year before the filming began, Schwarzenegger began preparing for the part. He learned to smile with paint on his face; to push his hair out of his eyes in a barbaric way; to wield a sword; to throw an ax. And, overall, to be a savage warrior, lover and citizen.

"I had to retrain my body from a healthy body to a more athletic body with a hungry look," he says, "so that the muscles look natural and not imposing, because a body builder's muscles look healthy and imposing. Well, in the barbarian age, you don't have food everyday.

"I had to practice to get rid of things we have learned up until now--how to take a fork and knife and eat the proper way. They just take the food and stuff it in their face. Or when you deal with a woman--it not this nice pickup situation. They have a more primitive way of doing it. So many little things you have to get down so you don't have to think about it on the set."

Schwarzenegger has always tried to get it right, ever since his childhood in Graz where, he once said, he had "the incredible desire to be recognized." He happened onto body building and, by the age of 19, was a competitive body builder, swimmer, soccer player, skier, wrestler and boxer.

When he retired from body building five years ago, he decided to write "Arnold: The Education of a Body Builder." He studied and researched for months and the book hit the best-seller list. His first movie, "Pumping Iron," based on his life, got rave reviews.

Women started to fall all over him--pinch, polk, grab. One even disrobed for his benefit at a Detroit book signing and the press dutifully reported this. And for the last two years the gossip columns have been ripe with notes about his romance with Shriver.

His successes quickly got him the reputation of being disciplined, shrewd, smart, savvy, and an opportunist. But Schwarzenegger counters.

"I have average intelligence . . . but in 1974 people thought body builders couldn't talk . . . I was on a talk show for the first time and when I said my first sentence--which was a normal sentence--I think they almost could get no air," he says with the deep laugh and tinge of sarcasm. "He, he can talk. It's so incredible. From that time on I got the reputation of being the smart body builder."

"Discipline," he says, "That's the way everybody sees it. The trick is to go after things that you really enjoy and then go for excellency in those areas . . .

"I'm planning to throw myself into acting. I will not give up until I am there--where I ought to be."