The chairman of the House Ways and Means Committee cautioned the Carter administration yesterday not to propose a tax cut next year to stimulate the economy, saying he does not believe it is needed and would block it in committee.

Rep. Al Ullman (D-Ore.) said in an interview he would oppose a tax cut for 1978 "unless there is overwhelming evidence that the economy has to have it," and he sees no such evidence now.

At the same time, Ullman relieved pressure on the administration to send up its tax package before Congress adjourns. The chairman had said earlier that such a timetable was necessary to ensure passage next year. But yesterday he urged Carter to wait until the pending energy legislation passes a Senate-House conference committee, lest the tax and energy plans become entangled politically. Senate leaders have given the President similar advice.

Ullman also said flatly he did not think Congress would accept a key part of the expected Carter plan - a proposal to tax capital gains at death. Instead, Ullman hinted he may try to revive his own proposal - defeated last year - for an "appreciation tax" on gains at death.

Capital gains are profits from the sale of stocks or other assets. Under present law, only half of a capital gain is subject to tax, and there is no income tax at all on such gains at death would be a major omission.

Yesterday's developments came as the administration continued to delay its completion of the tax-revision package, with key officials still uncertain about when the President plans to make final decisions on its contents or formally send it to Congress.

The administration has been leaning increasingly toward a 1978 tax cut as fresh forecasts show the economy likely to slow more than expected late next year.

Ullman did not flatly rule out the possibility of a 1978 tax reduction.

But he said that unless the economy really begins to falter, he believes the tax-cut provisions in Carter's plan should be kept together with the so-called "loophole-closing" portions to provide balance and equity. Some fear separating them and approving the cuts first could jeopardize "reform."

Ullman also rejected sd "bad tax policy" a Treasury proposal to produce a temporary tax cut early next year by speeding up reductions in witholding rates that the Carter package otherwise would schedule for 1979. "When a taxpayer gets a reduction," he said, "it ought to be based on a change in the tax code."

The chairman's proposal for an appreciation tax on capital gains would impose a modest levy of 5 to 15 per cent on the increase in the value of an asset held to the time of an owner's death. The measure was considered by his committee in 1976, but lost by two votes.

Ullman at one point also suggested that Congress "may have to bobtail" some portions of the Carter tax package, particularly of ficials decide to press for a tax cut in 1978. "I don't think we can digest it all next year," he said.

The Ways and Means chairman endorsed several other proposals the administration has been considering for its tax package, such as partly reducing the "double" taxation of corporate dividends, ending some personal deductions and tightening some tax preferences.

However, he cautioned that some expected Carter proposals to cut back deductions for business expenses "may present some problems." He referred specifically to a bid by the administration to limit deductions for business meals to 50 per cent of their cost.