Boston — Despite some losses in key campaigns, black people achieved new political clout in the Nov. 2 elections, says Eddie N. Williams, president of the Joint Center for Political Studies, a black political think tank based in the nation's capital.
But some of those close races have left black people around the nation shaking their heads and mumbling, ''Racism!'' Perhaps the biggest defeat came when Mayor Tom Bradley of Los Angeles lost his bid to become the first black elected governor of a state.
Racism as a factor was whispered, but not publicly stated until two weeks before election day. William Roberts, campaign manager for George Deukmejian, the California winner, said a hard core of voters would never vote for Mr. Bradley. Post-election surveys reported 3 percent of the voters said they could not vote for a black person - about 100,000, nearly twice Bradley's losing margin.
Nevertheless, Mr. Williams lists some significant results of the Nov. 2 elections:
* Blacks won three new seats in Congress - Katie Hall, a state senator from Gary, Ind.; Alan Wheat of Kansas City, Mo.; and Edolphus Towns of Brooklyn, N.Y. The House now has 21 blacks, all Democrats, the most in the nation's history. Twenty are state representatives and one is the Washington, D.C., delegate to Congress.
* More blacks, 363 (290 Democrats, 70 Republicans, and 3 independents), ran for office than ever before in a nonpresidential year. This total included 41 for Congress and 15 for statewide office.
* The black vote proved to be crucial in several elections, especially for gubernatorial winners George Wallace in Alabama, Mario Cuomo in New York, and Mark White in Texas.
* Many blacks delivered a ''resounding rebuke'' of Reaganomics by voting a straight Democratic ticket, according to Williams. The Joint Center said its spot checks of selected districts indicated that black voters cast more than the usual number of straight Democratic ticket votes. This ''anti-Reagan'' vote led to the defeat of black Republican candidates, Williams says.
Ronald McDuffie, executive director of the National Black Republican Council, agrees. ''We lost because we got a late start, and black people voted Democratic ,'' he says. ''We are committed to working for a black Republican in Congress in 1984.''
Some blacks who may have benefited were two Democrats, Roland Burris for controller in Illinois and Richard Austin for secretary of state in Michigan, who won reelection. Two black judges were elected to state supreme courts: Oscar Adams in Alabama and Allen Broussard in California.
Such straight ballots, however, may have costs blacks a chance to achieve clout in the GOP. Two highly regarded black Republicans, Lucy Patterson for Congress in Dallas, and Virgil Brown for secretary of state in Ohio, lost. Mrs. Patterson made a poor showing not only because of the voting pattern of black people, but also because she denounced the GOP on the eve of the election and lost ''the white Republican vote, too,'' said Paula Brown of Dallas, a black Republican who was a key worker in the campaign. ''We Republicans have to find more grass-roots votes and cannot be ashamed of our party.''
In Ohio, Mr. Brown did not get the black vote in his own Cuyahoga County (Cleveland) where he is chairman of the County Commission, although such black Democrats as Congressman Louis Stokes endorsed him, says Mr. McDuffie. Brown did well in Columbus and Cincinnati, he adds, but the anti-Reagan vote cut him down.
And in some races, candidates did not amass votes needed to elect black candidates, such as Robert Clark, who sought to become the first black member of Congress from Mississippi in this century.
Blacks, both well known and at the grass-roots level, expressed disappointment in Bradley's defeat, blaming his loss not only on racism, but possibly on his being ''nonracist'' in his campaign.
''The Bradley defeat casts a strong question of the acceptance of blacks in this country,'' said M. Carl Holman, director of the National Urban Coalition. ''It will be interpreted that America professes lots more than it practices.''
''Eventually the day will come in the political arena when a man like Tom Bradley can run on his qualifications as a public official and not on the color of his skin,'' remarked activist Dick Gregory.
Ronald Brown of the National Democratic Committee said, ''I'm very distressed. When a man like Bradley can't win in a state like California with 60 percent Democratic registration, what can blacks do?''
Says Mildred A. Kyles, Detroit homemaker and political activist: ''I don't consider Bradley's defeat a loss for black people. His showing says a black can be elected to a major office.''
Mary Helen Thompson, a public relations specialist for Sen. Paul Tsongas (D) of Massachusetts, suggests Bradley ''underplayed his blackness too much.'' She asks, ''Is his colorblind approach to politics realistic?''