How will Ferraro play on Main Street?

From now on, the 1984 race for the White House moves along a road with few signposts. After months of debate and polling, no one can can know how the nation will take to a woman on the presidential ticket.

All that is certain is that the gigantic gathering that shouted for Rep. Geraldine A. Ferraro's nomination by acclamation was swept away in the moment of history. Women danced with abandon on their chairs, while union men and blacks and Hispanics cheered. Hardly a lapel was lacking a ''Woman V-P'' sticker.

''She's living every woman's dream,'' proclaimed a Cleveland woman in the roar of the crowd.

''We're making history right now,'' said Jan Carrier of Ketchum, Idaho. ''I'm so thrilled to be here and be a part of it.''

Men seemed almost equally caught in the excitement. ''I'm glad for me and for my daughter and for my mother and sister,'' said a beaming Bill Thornby, a union official from Boise.

''I think she's going to be the greatest asset of the Democratic presidential campaign,'' held Bill Bowen, an Ohio state senator who is black. ''It exemplifies the American dream that you too can make it. Barriers are breaking down.''

For Democrats united by little except a common desire to defeat the incumbent , the candidacy of the New York congresswoman has injected a positive note for the start of the campaign. More than any other factor, Walter F. Mondale's vice-presidential choice has lifted the flagging banners of his party.

But winning over a few thousand political activists is a long way from wooing the millions that the Mondale-Ferraro ticket need to win in November. Within days the campaign will come face to face with voters like a San Francisco cab driver who said, ''She may come on too strong'' and added, ''I like women the way they are,'' which presumably is not in the White House.

Pollsters don't know exactly how Ms. Ferraro will play on Main Street. Surveys are unreliable in this uncharted territory. Respondents might not tell their real feelings. Mondale campaign manager Robert Beckel said he has scratched the strategies for targeting states because with a woman running, ''the book's being rewritten.''

Meanwhile, the US representative who is going to write the book on women running on a major party ticket embarks on the most closely watched vice-presidential campaign ever. Her every syllable will be weighed, her appearance rated, and her relationship with the presidential nominee scrutinized as the public attempts to satiate its curiosity about her.

In her first few days as a candidate she is already beginning to fill in some of the blanks. Never known as a dazzling speaker, the lawmaker, who is more accustomed to addressing gatherings in her Queens district, spoke to the nation with apparent ease and confidence. In the past she has sometimes hurried through speeches, but in San Francisco, her speaking pace was good.

Sen. Dale Bumpers of Arkansas, once seen as possible candidate, called her a ''low-key speaker'' after she addressed the convention and added, ''I think it's well that she is.''

The public liked her, said Democratic pollster Peter Hart, whose tracking of the Thursday speech showed her approval rating jumping up 10 points, although he declined to give exact figures. He reported only that her rating is ''high.''

In her first encounters with the news media, she is already having to fend off questions about her husband's real estate ownings (she will release a full disclosure, she promised), and about whether she is a true Roman Catholic, since she is pro-choice on abortion.

When asked on CBS-TV how she responds to doubts about her vice-presidential qualifications, she shot back, ''Quite frankly, I don't. I am now the candidate. I anticipate that ... come November the American people are going to vote Fritz Mondale and me into the White House, and ... they're going to get to know Gerry Ferraro very, very well.''

In Washington, she has sometimes shown hair-trigger reactions when reporters asked questions of a less-than-favorable nature. The next weeks will tell how well she can deflect criticism. A campaign spokesman expressed satisfaction that she did not overshadow the nominee at convention's close. But once the two begin campaigning, she will almost certainly be the centerpiece.