The President's Private Sector Survey on Cost Control, a controversial panel of businessmen appointed last year to find more efficient ways to run the government, has found a more efficient way to run itself: its 158 members have been whittled to a select group of 34 who will be responsible for coming up with recommendations.

J. Peter Grace, chairman of W.R. Grace & Co., who heads the panel, said the smaller "subcommittee" was "the most effective and efficient" way to sort through more than 25,000 pages of reports, backed up by 1.6 million documents, that have been put together by the survey's 36 task forces.

In a brief public meeting Friday, the group's first since it was created by President Reagan last June, Grace said the survey expects to make about 3,000 recommendations that could "result in tens of billions of dollars in savings."

The survey, which is financed by private business, has been under attack in Congress for the way it has conducted investigations into the work of more than 60 departments and agencies. Critics say the survey's task forces, composed of more than 1,200 business employes, were set up to circumvent federal open-meeting laws, and task force members have been poring through government files that involve their industries.

But in a press conference after the meeting, Grace said he knew of no task force member who had found anything of value to his employer. "I've picked up nothing but a lot of ideas about what not to do," he said.

"We have looked at some policies," Grace conceded Friday, but he added, "We have no power at all.