The House Public Works and Transportation Committee approved yesterday a $66 billion, four-year highway and mass transit bill after making a number of changes to please the Carter administration.

"We think the turkey has grown wings," a key aide to Tranportation Secretary Brock Adams said after the committee completed a two-day mark-up session. Adams had attacked the subcommittee version of the bill as a "turkey." Then, mixing metaphors, he had said, "It's pure pork barrel."

Absolutely no pork was removed from the bill by the full committee and a few million dollars were added. The technical changes pleased Adams' people, however, because they strengthen their position before the conference committee with the Senate, where the final bill will be writen.

Among the key changes, in the view of Transportation Department officials, are language in the bill that would promote joint planning efforts for both highways and mass transit in big cities, and an agreement that the states must decide by 1982 whether they are going to complete unfinished segments of the interstate highway system.

The committee bill also includes $50 million a year for the improvement of joint-use transportation facilities in big cities - the "intermodal connections" feature of President Carter's urban policy.

The bill has $36.5 billion for highways, $11.5 billion for highway safety and $18 billion for mass transit. About two-thirds of the total would come from the highway trust fund, according to committee staff, with about one-third from general revenues.

The administration bill had proposed that, if interstate projects are eliminated, the money could be shifted to other highway or transit projects at the same federal-state matching ratio used for interstate highways: 90 per cent federal, 10 per cent local.

That did not fly with the highway interests and the status quo remains. If an interstate highway is canceled, the money can be used for mass transit, for example, but at an 80 per cent federal, 20 per cent local ratio.Just such transfers have made it possible to continue construction on the Washington Metro, for example, when the original funding was used up.

Interstate highways had previously been the only major program receiving 90 per cent federal aid. Bridge replacement was added to that category by the committee's efforts, and the level of funding to replace America's failing bridges was increased from $450 million to $2 billion.

The administration was unsuccessful in seeking to eliminate a requirement that Adams re-evaluated his decision of last year that requires all new transit buses to be accessible to wheelchair-bound handicapped people.

Then there is the Jetfoil Demonstration Project, a proposal of Rep. James Howard (D.N.J.), the subcommittee chairman. The subcommittee bill included a $30 million authorization to study Jetfoil - a high-speed, over-water machine - as a means of connecting Howard's District with New York City. Howard offered an amendment yesterday changing the name of the project to "Waterborne Transportation Demonstration Project for the "vicinity of New York, New York." The change in wording, he said, would "take some of the pork out of this bill . . . and make it moreflexible." The change was approved.