"Just because a guy gets in a ring and turns around and around and screams and throws a discus doesn't make him great," rumbled 40-year-old Al Oerter, who is busy these days making a comeback in the discus event after an eight-year layoff. he won gold medals in four consecutive Olympic games, 1956-68.

"I'm working on a small scream," Oerter said, suppressing a chuckle. "Just a little primal scream."

It is as if Al Oerter sees exactly how ludicrous his life situation really is. He is trying, but he, like most of us, can barely hold back a belly laugh. "I'm not a jolly man," he insists, amidst contradictory bubbling laughter. "I hate everything."

Everything but discus throwing, that. "I enjoy the movement of the sport," he said. "I work very hard at the technique, the small body movements that take poise and balance.It's just like the movements required of a dancer."

But even that is ludicrous - a bear-sized man who looks like a fugitive from the Oakland Raiders' front four mincing around in an 8 1/2 foot circle trying to sling a 4 1/2 pound metal plate farther than anyone else in the world. Al Oerter has not given up his white-collar job as manager of data communications for Grumman Data Systems. He is merely moonlighting to compete in the discus.

"I miss sports itself, not particularly the discus throw," he said of his eight-year hiatus. "In the interval I have played tennis and jogged, but I never got the same feeling of competition. I was making a film with Bud Greenspan about the last Olympics and all of a sudden I felt good about the whole thing. It was no bolt out of the blue, but it was apparent that all the pressures of 1968 were gone. When I though about competing, it was a very pleasant thing.

"I've reached a point in life where I enjoy everything day to day. I'm not worrying about past pressures and will I be able to make a comeback. I'm not worried about my future: can I win?

"I'm not a George Blanda. I've got no managers. No team to say, 'Well, it's too late, kid.you have to do what's good for the team.'" Here, Oerter split with laughter. It bubbled over the telephone wires from Lawrence, Kan., where, last weekend, he won the discus event named for him by his alma mater, KU.

Because Al Oerter is having fun. Forty is fun is what Al Oerter is telling the world. There is no way he can lose.

If you press him, he confesses that he hates the world of computers. And, as an escape, there is something pure and fundamental about slinging the discus. Since no one really expects the middle-aged father of two teen-age daughters to be a menace in a track and field event, Oerter has absolutely nothing to lose and everyting to gain.

He is 6-foot-4, down from KU competitive weight of 298 pounds to a svelte 275. He says he aspires to "300, maybe 310 pounds.

"When I gain my strength by the end of the year, then I will convert the strength to throwing power. Then I will work on the torque. But now I lift weights, work on gymnastics and run. Last Monday I Bench-pressed 460 pounds: I will do 500 pounds soon. I have a series of lists: a routine for my lower body and a different routine for my upper body. It's not pumping iron for physique; it's pushing steel and caring about developing muscles and tendon flexibility."

But he says, "I don't want to compete against Mac Wilkins (current world record holder of 232.6 feet) yet. He'd beat me by 68 feet and I'd go back home and want to work out four hours a day instead of two," said Oerter.

"The discus world record doesn't mean a lot," he said from experience. "If you can get into a wind valley, it acts like an airfoil and you can add to feet to your throw if you know how to use your velocity. It's like a surfer taking advantage of the wave.

"And I'm not totally into it," he said with a laugh. "I mean, I don't have a ring drawn in my living room and weights in the bedroom. In fact, I don't have anything at my house except two discuses. And I keep them in the garage. The only reason I have two is that I'm too lazy to throw and walk and retrieve just once."

Oerter claims he was born to be a discus thrower. "There are two types of muscle fiber - slow and quick twitch. I'm a quick twitch. I was always strong; I could throw a baseball a country mile. I enjoy motion itself.

"I never have to psych myself up the way some people do, walking around talking to themselves, hitting themselves. I always went into competition high as a kite. I'm always psyched up with a great rush of energy."

There is a T-shirt for sale on the market that sums up Al Oerter's message. It is a universal wish from the middle-aged sector for Oerter's continued good luck. The slogan reads: "Forty is Forever." Al Oerter may be our last chance to prove it.