Citing the typical slow pace of housing inspections in the city, the D.C. City Council voted yesterday to allow a shortcut in the proposed law that is intended to curb housing speculation by taxing excessive profits.

After voting on the amendment, the council put off enactment of the bill until March 21. Final action had been scheduled for yesterday.

The proposed measure would tax profits made by dealers who buy residential properties, hold them for short periods and resell them, often at inflated prices. It is believed to be the first such measure in the nation that applies to urban property.

Most properties on which substantial rehabilitation work has been done will be exempted from the new tax.

Under provisions that received preliminary approval Feb. 21, a real estate dealer who has done rehabilitation work on a house must have it inspected by the city before it can be resold. The measure says the city has 20 days to make the inspection and certify the unit as meeting all regulations.

At yesterday's meeting, several council members said it is widely accepted that the city has a backlog of inspections, causing long delays.

To avoid delays, City Council member Marion Barry (D-At Large), the chief sponsor of the bill, proposed an amendment that would permit an inspection by a qualified individual if the city misses the 20-day deadline.

The amendment was approved by a vote of 9 to 3, with council member Wilhelmina Rolark (D-Ward 8) calling it "a devastatinly weakening amendment."

In other matters yesterday the council:

Voted a symbolic, but not legally effective, ratification of the Equal Rights Amendment.

Instructed its Government Opertions Committee to revise a proposed measure that would bar the spending of city money for meetings in any state, including Virginia, whose legislature has not ratified the ERA. (Mayor Walter E. Washington already has issued an executive order barring such spending.

Reenacted a bill, vetoed last December by the mayor on a legal technicality, that granted a 7.05 percent pay increase to 12,000 police, firefighters and teachers for the 1978 fiscal year. (The raises remain in effect under separate, temporary emergency legislation.)

Gave preliminary approval to a resolution naming the 900 block of G Street NW, outside the Martin Luther King Jr. Memorial Library, in honor of the late Sen. Hubert H. Humphrey (D-Minn.). The block has been converted into a pedestrian plaza.

Voted emergency legislation proposed by council member Nadine Winter (D-Ward 6) to assure the filling of all vacancies on the city's 36 Advisory Neighborhood Commissions that result from gaps in the city's election law.