Eleven a.m. on the 46th floor and writers' reputations are being made and not made. Ten-thousand-dollar deals and $85,000 deals, best-seller lists and movie rights, TV specials and spots on the Carson show, all hinge for a long moment on the tip of a woman's pen. After taking one minute to decide a frizzy-haired woman in a lavender sweater will mark a word on the cover letter of a manuscript.

"Yes" and the book will have made it through the first round and have a chance for the big rep, the big money; "no" and it will be out of this arena forever. "Yes" and the book may ultimately be plugged to the $1 1/2 million members of the Literary Guild, the biggest book club in the world. "No" and unless the other big book club picks it up or a publisher pushes it hard - the book may well fall into the remainder stacks early.

A "yes" and Rollene Saal, after reading the book and consulting with her staff - may have changed an author's career.

And this morning, Mrs. Saal, the 45-year-old editorial director of the Literary Guild, is doing what she does every morning, skimming the dozen or so manuscripts that arrive at the Guild's Park Avenue offices, determining what will remain for scrutiny and what will be discarded. The only difference is that this morning, because the press is standing by Rollene. Saal may be a bit more lenient because, as she says, she hates for any writer to be hurt. So here goes:

"'A Self-Help Encyclopedia From Arco Publishing. They're a strange little house, but we will read it because we do very well on self-help books.

"'Katie' by B. J. Chute. She was a National Book Award winner and this is her ninth book. I know her work and it's quite lovely but I don't think it will be for us. She writes rather slender, mild fiction . . . but yes, we will read it because it's a novel and we always read fiction."

"Yes" on Bobby Seal's autobiography because "he was the head of the Panhters and it could be a new look at the '60s, though it seems unlikely."

"The Clam Lake Papers," a book Rollene Saal requested, by a university professor who finds an intruder has camped in his vacation home and his written letters about the stay, gets a "yes."

She rejects an Academy Awards quiz book - "too special interests, it would be okay for a movie club."

Yes on Irene Kampen's "Fear Without Childbirth." "She's amusing, and it is a novel.

"The Sound of Their Music," the story of Rodgers and Hammerstein. No, because we've done a Richard Rodgers book, his biography. The author of this one, Frederick Nolan, is sort of a professional writer; it's not like a musician who spent his whole life with Richard Rodgers."

Rollene Saal is not comfortable talking about how powerful she is. Ask her if she would consider herself one of the more powerful people in book publishing and she'll look down, allow herself a small, quick smile and say, "That would be very self-serving of me say." Then she'll laugh. "Well, yes." The she'll quickly cover her tracks by switching to the first person plural: "It is true that if we buy a book because we have a strong opinion, we're hopeful that it is an educated opinion."

The plain fact is that Rollene Saal is plenty powerful, regularly dispensing six-fixgure sums for authors and agents. But her power is not the sort that has fame as its handmaiden.

At the Literary Guild's black-tie 50 the anniversary party at the Waldorf Astoria this week, most of the celebrity writers and a number of literary agents had never heard of her and made no fuss over her. (This was not surprising because Saal never negotiates directly with writers or agents.) Publishing executives, however, with whom Saal spent most of the evening, were aware of her influence and they acknowledged privately that much of that influence comes from the growing clout of the Literary Guild.

For the 14 major selections every year - the books sent to members Rollene Saal makes the final decision.

What does she look for in making her main selections?

"Heft in hand," Mrs. Saal, who describes the Guild as a mass market club with a high percentage of women. "We tend toward the big novel, not only in terms of size but in content. The book has to have complexity of characters, psychological relationships, unweaving of a complicated people plot. We all like the same things. Our tastes may be move or less sophisticated, but everybody likes a good story."

And does the ironic, sophisticated Mrs. Saal, a Wellesley graduate the sort of New York liberal who named one of her children after Adlai Stephenson, ever find that Guild selections differ from her own tastes? There's nod yes, then a spoken "no."

"I like 19th-century fiction very much. I like poetry a great deal and smaller slender British novels delight me, but this is not a mass market taste," she says. "On the other hand.I also like what the British call the Big Read. With no condensation. I thought Thorn Birds' was a terrific book."

She reaches across her desk, removes "Thorn Birds" from her shelf, passes it along. "Heft in hand," she repeats, "look at this, I love it. It makes you just want to snuggle up on an afghan. There's just something about a big book."

What won't they print? "Poetry," says Rollene Saal.

"Our members are just not terribly receptive to it. And small South Anerican bofel. As puslisher has been able to have success with them. Apart from "One Hundred Days of Solitude," "name me a south American noveletde. And how often to you hear anybody saying they can't wait for the new book from Bogota."

She rankles under mention of criticism of book clubs for the low-brow tastes, noting that Guid authors have included Elie Wiesel, Saul Bellow, Lillian Hellman, Jerzy Kosinski and Robert Penn Warren.

"We want our main selection to thrill and delight a lot of people," she says, "but the club is so large, that in the alternates we have the leeway to do almost anything; special interest books like 'Fodor's Railroads of the World' or 'How To Make Afghans', two rather off-beat books like 'The Managerial Woman' or 'The Serial', or a Margaret Drabble or an Antonia Frasier, who would be quite upscale. But that's the fun of it, you don't have to be a brilliant editor to understand that Herman Wouk, Graham Gracene, Leon Uris, and Philip Roth are your big guns. But ferreting out smaller books, what publishers call 'middle range,' that's the real challenge."

As Mrs. Saal tells it, she was not more than 10 or 11 years old, Rollene Waterman, the doctor's oldest child, in Plymouth, Mass. when she knew she wanted to be "a writer, editor, poet - anything to do with books."

She took the standard route. She graduated from Wellesley as an English major, came to New York for a series of not-quite-right publishing jobs before finding her niche and settling in.

She moved to "Saturday Review" where she reviewed books and interviewed authors. She also married (Hubert Saal, a Newsweek editor from whom she is now divorced.) had three children, moved with her family to Florida, where her husband taught and she became a columnist on The Miami News.

"It was the days of 'whither thou goest," she says now of the move to Florida with her husband, "and the newspaper job was wounderful. But I never let go of my New York thread. I was a reader for the Book-of-the-Month. I reviewed for Saturday Review. I kept my publishing ties - they were like my lifeline."

The family returned to New York and seven years ago Saal joined the Literary Guild as a reader. She is today, in addition to being head of the book club, the first woman vice president of Doubleday. When Simon and Schuster sent her the manuscript of "The Investigation" on Friday, she had her club's offer of $100,000 in the following Monday, "I don't feel skittish about bidding," she says, "because if we are in the position of wanting a book then we'd just feel right about it.

"Blood and Money,' could have been viewed as us taking a chance because Tommy Thompson, though he was a Life magazine writer, was really nothing; he was not a name like Leon Uris, but he subject may so rich i r really wasn't risky. Who would not want to read about love, passion, murder and a doctor in rich eqylent Texas?"

"In our April selection, The Last Convertible' is by a man you probably never heard of, but I think it will do very well. It's the story of a young man who arrives at Harvard as a freshman, on the eve of World War II, and one of the men, a dashing Frenchman, gives the other man the keys to his convertible and the novel is the lives of these men, through the changing decades: the women they marry, the women they should have married, intermingled with Vietnam, the '60s, all against the rich evocative atmosphere of Cambridge . . ."

Not surprisingly Rollene Saal's life is dominated by books, rich evocative and otherwise.

Up at 6:30 a.m. on work days, she's flipping the dials of the morning TV shows by 7, because those shows "do a lot with books." Office time is taken up with meetings, acquisitions and negotiations, with most bidding taking place on the phone. Lunches are for publishers or book parties. And evenings not spent at social gatherings connected with publishing are generally passed at home with a pile of manuscripts nearby.

Housekeeping and child rearing are aided by a part-time housekeeper. "The children are terribly cooperative and supportive," says Saal, of Drucilla, 10, Matthew 12, and Theodora, 15.

Weekends, she sometimes spends in the country but three manuscripts fit in her overnight bag quite well and tress, she finds, are for reading under. She has trouble remembering the last movie she' s seen. "Rocky," she says after a long puse. "last November."

As for vacation time, "I go the Europe, certainly, every year . . . to the Frankurt book fair."

And did this maven of the mass market best-seller ever miss out on a big one?

With not a bit of embarrassment, rather like a college girl getting into a good gossip, she tells all. "My secret story, of the one I let get away, happened when I was very junior, I mean a fairly junior person here, and I was a reader for 'Sexual Politics,'" she says, "I felt it was a literary exegesis territie for a Ph. D. work, but heaven knows not a book that people would ever read. And that haunted me for a long time as it hung in there on the best seller list.

"Still, I wasn't altogether wrong in my opinion; it was a literary exegesis, it did take almost total concentration from the reader, but it was the moment for that book, the moment for a book on sexual freedom, and that's what I know now about publishing. You don't just need to catch the book, you also have to hit The Right Monent.