The Lyle report is a dud, and not the dynamite it was cracked up to be, according to sources on the House committee whose members got a look at it yesterday behind closed and guarded doors on Capital Hill.

Terming the report a "disappointment . . . a rehash . . . badly written and totally lacking in sex appeal," some of those who saw it even praised the Carter administration for its "responsible effort to keep the report secret."

The document, which concerns allegations of abuses of the federal merit system by civil service officials in the Nixon administration, was written by a volunteer on the Carter transition staff. It had stirred up a classic tug-of-war between members of Congress and the White House over access to its contents.

Some members of Congress had threatened to use the issue to stall the President's civil service revision bill. To prevent this, the White House finally agreed to show them the report in closed session yesterday.

"I think we're all convinced now that they (the administration) are not suppressing anything but are attempting to be responsible," said Gladys Spellman (D-Md.), a key member of the House Post Office and Civil Service Committee who had been pressing for a copy of the report.

"Nothing really dramatic there," said Rep. James M. Hanley (D-N.Y.), who is in line to become the committee's next chairman.

"Much ado about nothing," said Rep. Edward J. Derwinski (R-Ill.), the committee's ranking Republican.

These and others on the committee said they feel that the Lyle report has been defused as a threat to the progress of the president's civil service overhaul legislation.

Until last week, the White House had resisted pressure to let members see the report, on grounds that to make it public would violate the civil rights of the people it names and jeopardize an investigation now under way into these and other charges.

Several members insisted they needed the information to evaluate the proposed legislation. They also expressed concern over reports - denied by the administration - that some of the alleged wrongdoers named in the report had helped write the Carter administration's civil service legislation.

A number of sources on the committee had complained that the Lyle report was being used by opponents of the legislation as a diversionary tactic, and that the White House was playing into their hands by refusing to release it.

After seeing what she called the "raw allegations" in the report, Spellman said yesterday that she thinks Civil Service Commission Chairman Alan K. Campbell "is actually being a very decent man" in resisting the release of the report.

Campbell earlier had assumed blame for the flap, noting that it was on his recommendation that the administration had tried to keep the report's contents secret.

Campbell had hired a private law firm to conduct an investigation of these and other charges at the Civil Service Commission. Those findings are expected around the end of June, he said.

The Lyle report, 36 pages of which had earlier been supplied to The Washington Post by a federal employes union, is based primarily on past investigations conducted by Congress and the Civil Service Commission into patronage hiring and other abuses, and on some personal interviews. Derwinski noted that it also contains copies of articles published in The Post, The Washington Star and the Federal Times.

Spellman and others predicted that some opponents of change in the civil service system may still try to use the Lyle report "to duck the real issues . . . to avoid biting the bullet" in such tough categories as labor-management relations and chances in the veterans preference law.

The civil service committee members should "come to grips" with these issues on their own merits, Spellman said.