The House Post Office and Civil Service Committee at a clamorous meeting filled with denunciations of the committee on Ways and Means, voted 24 to 0 yesterday to wage a major floor fight next week against dissolution of the federal retirement system, and inclusion of 2.5 million federal employees under Social Security.

Led by Rep. Gladys Noon Spellman (D-Md.) and spurred by heavy lobbying from federal employee unions whose members fear they will lose benefits from the federal employee pension system or be double taxed, the committee voted to offer a floor amendment to the big Social Security bill. It would knock out a Ways and Means proposal to bring federal government workers under Social Security automatically on Jan. 1, 1962.

The vote yesterday set the stage for a headknocking floor clash between the Post Office Committee and Ways and Means, which had voted 22 to 13 earlier to include federal workers under Social Security.

Spellman siad that no fiexed date for inclusion of federal workers should be written into law until the completion of major studies to see how and whether the existing federal retirement system and Social Security should be linked. She said even House Ways and Means Chairman Al Ullman (D-Ore.) considered the provision adopted by his own committee foolish and, in her words, "scatterbrained," because it mandated coverage before any studies had been completed.

Rep. Stephen J. Solarz (D-N.Y.) called the Ways and Means provision a half-assessed way to proceed."

The committee didn't reach a decision on whether it should also support a floor amendment knocking out mandatory coverage for state and local governmental workers.

Herb Harris (D-Va.) strongly opposed inclusion of federal workers under the Social Security system.

A group of spokesmen for the U.S. Conference of Mayors, National League of Cities and other municipal groups opposed mandatory coverage for their workers also, which is included in the Social Security measure, for fear it will end up costing the cities and countries more money.

Spellman said it was her thought that in view of "sock-it-to-federal-employees" sentiment in many places, it might be best to make common cause with the municipal groups to kill both new coverage provisions.

The Way and Means Committee voted to include federal, state and local government employees in part because it will bring a big new dollop of funds to the financially troubled Social Security system initially. However, the committee mandated that a system worked out so that federal employees, who pay higher contributions into the federal retiremnet system but get higher benefits, end up no worse off than they are now.

Most members of the committee, as well as actuarial and pension experts, assumed this would be done by revising the current federal employees pension system into a supplementary benefits system. Each person would get a basic Social Security benefit plus a federal retirement benefit on top of it - the whole to cost no more and pay as much as the federal system does now.

The main long-term advantage to the government would be that it would save some $1 billion or more annually that now goes to "double-dippers" who draw substantial benefits from both systems.

Experts said special provisions could be written to assure that an older federal worker who pays into Social Security for a few years gets some benefits from it - not just the tax - and loses none of his existing federal retirement credits

However, many federal workers fear that the matter won't end up that way - that they may have to pay Social Security taxes on top of the current 7 per cent federal retirement contribution, and get nothing in return, and their spokesmen have lobbied heavily against coverage now.