Irvin Kovens, a master fund-raiser in Maryland politics during the 1970s, has begun working on the 1986 gubernatorial campaign after a self-imposed political exile, which stemmed from his 1977 conviction on corruption charges as a codefendant of former governor Marvin Mandel.

Kovens, 66, a millionaire furniture dealer who served as Mandel's chief fund-raiser in the 1970 and 1974 elections, is raising money for his longtime friend, Baltimore Mayor William Donald Schaefer, according to a Baltimore businessman.

Morton M. Lapides, the chairman of Allegheny Beverage Co., said he was asked by Kovens several weeks ago to contribute to Schaefer's all-but-announced campaign for the Democratic gubernatorial nomination. Schaefer supporters are in the midst of a major effort to raise as much as $1 million at a Sept. 26 Baltimore event, which is billed as a tribute to the mayor's 30 years as a public official.

Lapides said he declined to contribute because he is supporting one of the mayor's rivals for the Democratic nomination, Attorney General Stephen M. Sachs, a distant relative. "I told him Kovens that blood is thicker than water, that I was for Steve for governor and didn't care to see Mayor Schaefer be governor," Lapides said.

Schaefer came close to acknowledging the fund-raising role of his old friend Kovens during a luncheon with reporters and editors at The Washington Post on Monday.

Asked if Kovens is actively involved in raising money for him, Schaefer replied, "I would think so. I think he would be."

Schaefer, serving his fourth term as mayor, has told numerous allies and Maryland politicians that he will be a candidate for governor next year, although he has stopped short of announcing his intentions in public. He is expected to declare his candidacy formally next spring.

Robert Hillman, Schaefer's chief fund-raiser, said yesterday that Kovens has played no role "that I know of" in selling tickets to the September fund-raising event at the Baltimore Convention Center. "I have 124 people who have been given tickets by the committee, and Mr. Kovens is not one of them."

Told of Schaefer's comments, Hillman said, "He may know more than I do."

During the luncheon at The Post, Schaefer speculated that his opponents would raise "my associations with certain people" as a campaign issue, and defended his longtime friendships with Mandel and Kovens.

Ticking off a list of city buildings and public works projects that were built or approved during the Mandel administrations, Schaefer said he "had a good working relationship" with the former governor, who served 19 months in federal prison after his conviction on mail fraud and racketeering charges.

Of Kovens, who served six months of a three-year term on the same charges, Schaefer said he is a friend who had never attempted to abuse their relationship by asking for "anything that wasn't proper."

Sources close to Schaefer said the mayor is purposely being forthright about his ties to Mandel and Kovens during the early stages of the governor's race in order to blunt expected attacks on that issue from Sachs, a former federal prosecutor who built his reputation on political corruption cases.

Sachs, who during his first race for attorney general in 1978, charged that Kovens was behind an effort to discredit Sachs' candidacy, declined to comment on Kovens' role in the Schaefer campaign.

Kovens, who could not be reached for comment, was widely regarded as the state's premier fund-raiser during the 1970s. He was the chief architect of the 1973 "Four Star Salute" event that raised close to $1 million for Mandel and his ticket mates.

Although Kovens has not been very visible in recent years, he briefly reactivated his old network of friends and associates in 1981 when he helped sell tickets to another Schaefer fund-raiser that celebrated the mayor's 25 years in office.

The scheduled gala for Schaefer is reminiscent of the "Four Star Salute," at least in terms of its size. Although the mayor's fund-raisers refuse to predict how much will be raised at the $100-a-ticket event and at a $500-a-ticket cocktail party for major contributors on the same day, it is widely believed that the goal is more than $1 million. Hillman said yesterday he anticipates that more than 5,000 people will attend the two affairs.