Because of the Iranian crisis and an overcrowded congressional calendar, the Senate debate on the SALT II treaty is unlikely to begin this year, Senate sources predicted last week.

Pro and anti-SALT maneuvering continues intensely in the Senate, but both sides now expect the floor debate to begin in earnest no sooner than January. It may be difficult to get a final vote on the treaty before the New Hampshire primary on Feb. 26, some Senate sources say.

Friends and foes of the treaty agree that continued slippage in the SALT timetable is likely to help the treaty's opponents more than the Carter administration.

The Senate majority leader, Robert C. Byrd (D-W.Va.), has expressed dismay at the prospect that SLT will be on the floor during the presidential primaries, but that now appars to be inevitable.

Byrd told reporters yesterday that in view of Senate delays on the windfall profits tax bill and of the need for a week or so for the Armed Services Committee to study five-year projections for military spending, it's only marginally likely that the treaty would even be made the pending Senate business before the scheduled Dec. 21 adjournment. And that final vote wouldn't come until many weeks, perhaps months, into the 1980 session.

Some opponents of the treaty scored public relations points last week with a strategic leak of a draft report that the Senate Armed Services Committee may consider soon that is sharply critical of SALT II.

Aides to senators hostile to SALT II leaked the document, a 31-page report written by staffers which had no official status, and claimed that 11 members of the 17 member committee would endorse it.

At least one of the alleged 11 supporters, Robert Morgan (D-N.C.), said he would oppose the proposed report if it comes before the committee, but there appeared to be majority support for a strong anti-treaty statement, if the committee decides to make any statement of this kind.

Treaties are outside the furisdiction of the Armed Services Committee, and some senators, probably including Chairman John C. Stennis (D-Miss.), may oppose a committee finding on SALT II.

Treaty supporters on the committee were angered by the leaks. One, Gary Hart (D-Colo,), called the leaked draft report "a hoax," since it had no official status, and had not even been circulated to the full committee.

Numerous aides and other Senate sources said the report was the work of Richard Perle, the resourceful defense policy aide to Sen Henry M. Jackson (D-Wash.). Perle acknowledged helping write the report, which he called a "collaborative effort" of several Senate offices.

Behind the scenes last week, the Carter administration continued its efforts to placate senators (and former secretary of state Henry A. Kissinger) who have demanded increased defense spending as the price for their support of SALT II.

Defense Secretary Harold Brown met during the week with Sen. Sam Numm (D-Ga.) and Kissinger, and with both Byrd and Stennis to discuss additions to the defense budget. Administration officials have also met with more dovish senators who are unenthusiastic bout increased defense spending to explain their position.

According to well-placed sources, the president is likely to approve a 3.6 percent real increase, after inflation, in the fiscal 1981 defense budget.This is a much bigger increase than Carter planned before defense spending became an issue in the SALT debate.

In the subsequent four years, these sources said, the president will probably propose annual increases of more than 4 percent per year in defense spending. If appropriated, these increases could bring the defense budget close to $200 billion a year by 1985. However, strong congressional opposition to such increases is expected.

Nunn declined to say last week what his inclinations on SALT are, adding that he wanted to wait for the president's final decisions on the defense budget, which may come this week.

Some SALT opponents in the Senate began predicting that Nunn would end up supporting the treaty, though perhaps not with much emthusiasm. Administration lobbyists regard his support as crucial.