To meet Nick Nolte is to understand that he is not a piece of beef playing himself, not the lunkheaded lout of "The Deep," not even the brilliantly menacing Ray Hicks of "Who'll Stop the Rain." Nick Nolte, the image and the publicity to the contrary, is almost obsessively an actor.

Nolte has a minimal physical connection with any of his roles. He wears cowboy boots, tired jeans, a faded "Loprinzi's Gym" T-shirt topped by a baggy tweed jacket, a large white cap over his shoulder-length blond hair. He has a rambling, shambling way about him, a Woody Guthrie/Malibu surfer melange that is both charming and folksy. "This," he says, standing up and grinning, "this is what it is."

Nolte is standing to point out the physical disparity between himself and the coiled, muscular Ray Hicks. "I'm much looser and floppier physically and we (Nolte and director Karel Reisz) put tremendous physical control on the character," he says. "To emphasize Hicks' military centeredness, I wore a surgical brace for the entire shooting."

This intensity, this mania for detail, is typical of the way Nolte likes to work. He ice skated for five hours a day for four weeks to see if he could turn himself into a hockeyplayer for "Slapshot"; he couldn't. On "Who'll Stop the Rain," in addition to his wearing the brace, Nolte shortened and dyed his hair, concentrated on lowering his voice and did a lot of upper-body work with weights to give Hicks the solid look and feel he felt the character needed.

This total immersion extends to mental aspects as well, because Nolte, described by one writer as someone who could stand a couple of hours in a bar arguing persuasively that the world is flat, is the kind of actor who revels in endlessly talking about and exploring the characters he plays.

"When you find you've got a hole in the script," he says enthusiastically in his husky, whiskey voice, "that's really a super day. That really jives things up."

There were apparently many such days on the set of "Who'll Stop the Rain," filled as it was with not the most gregarious group of people. Robert Stone, author of the original novel, the National Book Award-winning "Dog Soldiers," "had had a bad experience with film (when his 'Hall of Mirrors' was turned into 'WUSA'), and was not enamored at all with film." He was approaching it a little light-footed. Co-star Michael Moriarty was "a very private actor," and then there was Tuesday Weld.

"Tuesday," Nolte slow-drawls, a kind of sly grin crossing his face, "Tuesday's been around the block about 150,000 times. She's reserved about what she thinks, waiting to see how it'll turn out. But about mid-point, she really turned it on, she knew we were into something."

It was precisely this that Nolte hoped would happen when he became involved with the project. "I read the book when it first came out; it was like 'Cuckoo's Nest.' You carried it around in your back pocket and asked people, 'Read this one yet?' he says.

"There's always paranoia in this business, you can never be totally sure. But you know when the material's good, and I always thought this was something you could go all the way with, a film that had the potential to have it all. You can't do that with a piece like 'The Deep,' you're in the wrong ball park if you even try."

Though he says he can't "criticize it ('The Deep') too heavily because it was laid out pretty concretely going in," Nolte is nevertheless frustrated about what happened with his first theatrical feature.

"All they wanted was something mechanical, scenes done without inter-relationships, little bridge scenes to lead you from gag (special effect) to gag," he explains. "I felt slighted, drained. 'Who'll Stop the Rain' was just the opposite. I feel very full with that role. We really achieved all that we set out to do."

Even Stone, Nolte reports, is relatively satisfied that the film was faithful to the spirit of his novel. Only one thing gripes him, as it does Nolte and everyone else. The last-minute title change.

"The studio was running scared at the tail end, afraid that the name 'Dog Soldiers' might turn some audiences off," Nolte says. "They did a test, but when you throw a title at someone out of context, of course they'll react negatively to certain words. Imagine if they did that with "To Kill a Mockingbird.' 'Kill a Bird'? That would be totally out."

Even with its new title, "Who'll Stop the Rain" is not busting many box-office safes. Nolte partially blames the ad campaign, "putting it out as kind of B-class adventure," but admits that because of its downbeat nature "the project was never approached totally as a commercial thing. No one thought it was going to be a terror, a smasheroonie. But I think it can hang in there and catch an audience. I told Karel that with its feeling for code and morality, this film will do best in Japan."

Nolte's next film will be "Heart-beat," in which he plays Neal Cassidy to John Hurd's Jack Kerouac and Sissy Spacek's Caroline Cassidy. It starts shooting Sept. 5 and Nolte is already constantly doing finger rolls with a silver dollar, a la Cassidy, to help him prepare. After that he hopes will come "North Dallas Forty," which will draw on Nolte's major experience before he came to acting: football.

Kind of a tramp athlete, Nolte played football for five colleges - Arizona State, Phoenix City College, Eastern Arizona Junior College, Colorado State and Pasadena City College - in four years. "I played every damn position, I kept re-transferring my high school transcript," he explains. "I never went to classes at all, I was just there to play ball."

When he saw he wasn't going to make it as a professional, Nolte turned to acting as "an outgrowth of the concentrating I gave to athletics. I'm a one-focus person, I want to concentrate fully on what I do, and acting gave me the same opportunities to do that."

Though he may seem an overnight sensation, Nolte, now 37, spent something like 14 years working on a little theater circuit that encompassed Phoenix, Denver, Minneapolis and Chicago, moving around much the way he did as a football player. "There was always a need for young male leads," he says. "All those guys were in either New York or Los Angeles, working in gas stations."

It was a little-theater production of William Inge's "The Last Pad" that finally brought Nolte to Los Angeles in 1973, where TV roles, including the breakthrough "Rich Man, Poor Man," followed rapidly. Yet his success, except perhaps in that it has enabled him to buy a 10-acre ranch in the Santa Monica mountains, where he lives with his wife, seems to mean very little to him. His main interest is still tinkering with old cars. The Land Rover in "Who'll Stop the Rain" is a prime reclamation project.

"I was just as happy then as I am now," he says of his little theater days. "It was a kick to put 'The Last Pad' together the way we first did it in Scottsdale. That was a full experience, and when you have one of those, then you don't care where the hell you are."