After 15 years of feeling that they were the pariahs of Democratic politics in Montgomery County, the county's businessmen have been somewhat surprised this year to discover they have become a heavily courted well-spring of money, endrosements and votes.

"We proviously were shunned and feared," recalled R. Robert Linowes, a zoning lawyer and president of the Metropolitan Board of Trade. "We haven't had his pro-business philosophy in three elections."

For years business, especialaly real estate, was blamed by civic groups in the "growth-no growth" controversy for the spreading concrete landscapes, traffic congestion and expensive new public facilities that drove up taxes. Business was aligned traditionally with the Republican Party, which represents only one-third of the county's electorate.

Now in the face of a brewing taxpayers' revolt over rising taxes and costly government, the three Democratic county executive candidates have begun preaching a new gospel of "economic development" to broaden the commercial tax base and reduce the home owners' tax burdens - a gospel that is very appealing to the business community.

"Everyone is falling over backwards over economic development," said Linowes of the three executives candidates - State Sen. Charles Gilchrist, Planning Board Chairman Royce Ranson and County Council member John Menke.

In their campaigns during the 1970s, Republican candidates verbally flayed Democrats for not being sufficiently supportive of business and unenthusiastic about commercial and industrial development of the county. The Democratic-controlled County Councils of the 1970s have been repeatedly labeled "ant business" by Republicans.

In this 1978 county executive campaign, three Democrats are actively seeking money and endorsements from the Board of Realtors, The Suburban Maryland Homebuilders Association, the Apartment and Office Building Association and other influential businessmen.

They also are promptly filling out questionnaires and asking to speak at breakfasts, luncheons and dinners of business people from Gaithersburg to Silver Spring.

Typical of their overtures is Menke's recent conversation with builder Ralph Duffy, who is sending a Menke endorsement letter to the building industry. "Someone suggested I phone him," said Menke. "We talked and he said even though he has disagreed with me in the past and probably will in the future, he considered me fair and open-minded."

One of the most dramatic displays of the new political mood occurred early in the spring when the Montgomery County Chamber of Commerce announced in a press release that it will entertain candidates at a cocktail party.

"I had candidates coming out my ears," said Achilles Tuchtan, the chamber's executive director. About 200 businessmen and 100 candidates showed up.

Back in February, Gilchrist slipped away from the legislature to attend the first membership meeting of the Committee for Government Accountability, a new nonpartisan group representing numerous businesses in the county. "I just like to go where people will have me," Gilchrist said at the time.

Hanson said he has told business groups on many occasions. "This business of talking about business and citizens as two separate groups, as if the people running business were aliens, is quite destructive and impeding the solution of many important problems in the county," he said.

This week, the homebuilders' political education committee has begun interviewing Montgomery candidates for the endorsements it intends to announce around Labor Day, a week before the Sept. 12 primary.

"Candidates in both Montgomery and Prince George's contacted us, volunteering for interviews," said Martin Poretsky, president of the homebuilders group.

"We're not making financial contributions as a committee," he added. Everybody is asking for money, but six months later they'll forget who gave and who didn't. We have what politicians want, which is votes." He estimated the home builders can have some influence on the votes of 30,000 construction executives and workers at all levels in the construction industry.

"Everybody believed business had taken enough knocks on the chin," said Joan Hatfield, lobbyist for the realtors and coordinator for the Committee for Government Accountability."We are a base of employment and taxes. We are a very needed commodity."

There also is skepticism by some business leaders about how long the rhetoric espousing the idea of economic development will persist, considering how unpopular the cause has been in the not too distant past.

"One candidate called me at home and said, but I have changed,'" said W. Edward Gregory, public relations director for the Pepsi-Cola Bottling Co. of Washington and a politically active businessman.

"I had to tell him that his past positions against business are indelibly written on my heart. 'You'll have to show me, 'I said."

Gilchirst is seen as most "harmless" in this contex, according to businessmen. As a tax attorney he worked with business and he has developed a reputation as "being somewhat of his own man," as one businessman put it.

Although Hanson has received contributions from large development interests and small businessmen, he has antagonized some developers as chairman of the planning board which has enforced the county's "managed growth" policies of the past eight years.

Menke, who successfully campaigned four years ago against the Dickerson sewage treatment plant that would have allowed considerable new development, said recently that those who would paint him as a former "non-growth" advocate were wrong.

"I was just perceived that way," said Menke. "I won't say I haven't learned . . ." Last year, Menke sponsored the legislation that ended rent controls that business always has opposed.

Despite their new political popularity, some businessmen still are reluctant to come on too strong in politics and some candidates are hesitant to promise too much.