Democrats on the Senate Judiciary Committee served notice yesterday that they will try to block all nominees for federal judgeships until the panel's Republican majority gives them more time to examine the candidates.

The simmering dispute over the speed with which the panel is processing judicial nominees boiled over at a morning committee session, when ranking Democrat Joseph R. Biden Jr. (Del.) told Chairman Strom Thurmond (R-S.C.) that the Democrats would no longer cooperate unless the process is slowed.

"Not a single judge will get out of my committee or off the floor, if we can help it, unless we agree to an orderly procedure by which we can process these judges and investigate them fully and fairly," Biden said yesterday.

Biden said he wants Democratic questions included in the panel's questionnaire to nominees and at least three weeks' notice for each confirmation hearing, plus another two weeks before each vote. In addition, he said, the Democrats must be allowed to designate certain nominees as the most controversial and to take "as long as we need" to examine their backgrounds.

Majority Leader Robert J. Dole (R-Kan.) and Minority Leader Robert C. Byrd (D-W.Va.) have been called into negotiations to settle the dispute, which could slow President Reagan's efforts to appoint a record number of federal judges.

Mark Goodin, a spokesman for Thurmond, said the senator hopes to work out a compromise but wants "to protect this process from being delayed on a partisan basis . . . . In some cases the confirmation hearings have become nitpicking sessions."

The dispute intensified after Thurmond rejected Democratic requests to delay a hearing scheduled for today on two controversial nominees: Jeff Sessions, the U.S. attorney in Mobile, Ala., who headed an unsuccessful prosecution of black civil rights leaders on voting-fraud charges, and Sidney Fitzwater, 32, a Texas state judge.

Biden said the Republicans are rushing through judicial nominees in about one-third the time that the Democrats allowed when they controlled the Senate. But he said the Republicans have tolerated an 18-month delay on the nomination of CIA general counsel Stanley Sporkin to the U.S. District Court here.

Sen. Jeremiah Denton (R-Ala.) yesterday was granted a fourth day of closed hearings on allegations that Sporkin improperly intervened in an FBI investigation of a leak of classified CIA information. Biden said Denton was "deliberately trying to delay for the purpose of defeating" Sporkin, who is opposed by many conservatives.

Despite yesterday's rhetoric, the panel approved the appeals court nomination of University of California law Professor John Noonan, an outspoken antiabortion leader and onetime advocate of restricting the authority of federal courts. The vote came after the Democrats obtained assurances that they would get to vote on Sporkin next month.