Eight years ago, the name, of anti-war activist Sam Brown caused a sound of gnashing teeth among some congressmen. The idea of his being named to head a federal agency with a $196 million budget and thousands of employees would have brought incredulity on Capitol Hill.

But, no longer.

If anyone needed a demonstration of how far the nation has put the Vietnam war behind it, it would take only the admiring and friendly reception Brown got at the Senate Human Resources and Foreign Relations committees yesterday as members questioned Brown on his nomination to head Action.

Action is the federal umbrella agency that includes the Peace Corps, Vista and nine other organizations that use 236,000 low-paid or unpaid volunteers to provide services to the poor at home and abroad.

After a brief hearing at which many words of congratulation and no words of criticism were directed at the 33-year-old Brown, the Foreign Relations Committee approved his nomination by voice vote. It followed up by approving Mary King as deputy director. The Human Resources Committee is expected to follow suit.

Gary Hart (D-Colo.) and Floyd Haskell (D-Colo.) beamed as they introduced Brown, who two years ago was elected treasurer of Colorado with the backing of a environmental coalition, as a man "as well equipped as anyone in this country" to head Action.

Not a word was spoken at either hearing about Brown's activities as Eugene McCarthy's presidential campaign coordinator in 1968 or his organization of the Vietnam moratorium and antiwar demonstration in Washington in 1969.

Some thought that Sen. S. I. Hayakawa (R-Calif.), who won fame as a hard-line critic and supporessor of sutdent demonstrations as a college president in California during the war years, might attack Brown.

But Hayakawa didn't even raise the point. "That's all in the past," he smilingly said to a reporter. Hayakawa said he was more worried about the possibility that enrolling young people for "leafraking" and similar community service activities "are copouts to avoid giving kids real jobs . . . They know it and it demoralizes them."

"It's a different era," Hart said when asked if Brown's antiwar activities could impede his confirmation.