Treasury Secretary W. Michael Blumenthal predicted tonight that the seven-nation economic summit beginning Thursday would set specific, country-by-country limits on import quotas for oil for 1979 and 1980 as "a strong signal to OPEC that we mean business."

At a press conference with a group of American reporters, President Carter's chief economics spokesman said that precise barrel limits for each summit partner might be listed in an annex to the summit communique.

Until now, the industrialized countries have agreed only to reduce imports by an amount corresponding to 5 percent of projected production. The aim of the summit, Blumenthal said, should be to "sharpen" this "vague" commitment by specifying allowable levels of imports in actual barrel terms. That would give each country an incentive to find substitutes in order to maintain consumption levels.

He said a specific limitation of this sort, country by country, "would take the pressure off the global market" and could add as much as 2 million barrels a day for 1979 and potentially more for 1980. The import limitation goal for 1980 "could be even tougher," he said.

For the years after that, Blumenthal said, more generalized import reduction targets might be specified, with the understanding that they could be reviewed periodically.

Blumenthal indicated that discussions here with the Canadian and French advance parties indicated agreement that the import limits "have got to be specific, will be specific and will be a strong signal to OPEC that we means business in that regard."

He later said that by "signal", he meant that the summit would thereby convey to OPEC the Western world's agreement with the cartel's insistence that a meaningful cut be made in consumption. The proposed European freeze of imports would not ensure a reduction in consumption.

U.S. officials, working more closely than ever with Japan, continued to make clear that neither country cared much for the European proposal made last week at Strasbourg that would put a five-year freeze on oil imports, with the Common Market considered as a whole.

Other officials pointed out that with North Sea oil production increasing, the Common Market as a whole could reduce imports over the next five years, and keep their supplies of oil stable or rising, depending on the actual volume of North Sea oil delivered.

Blumenthal said that one of the questions that had emerged with clarity during the past two days of the bilateral U.S. Japanese meeting "is that different countries have somewhat different situations confronting them.

"When we talk about limitations on the volume of imported oil, that is a more difficult thing for the Japanese to do than for a country that is already more heavily into substitutes for oil."

The treasury secretary also said that a country's current or anticipated economic growth rates would have to be considered in setting import limits.

"I would think one of the difficult issues to be resolved here will be finding a meaningful, strong set of numbers with a common denominator that nevertheless take account of the different conditions that different countries face," he said.

Blumenthal reiterated in a speech today to the Keidanren - the Japanese equivalent of the National Association of Manufacturers - that oil conservation is a limited tool, and must be supplemented at the summit by a massive effort to finance the production of new forms of energy. But he told reporters that the summit declaration would make no reference to a $10 billion worldwide production agency he and the Department of Energy had recommended earlier.

In contrast to the pattern of earlier summits, Blumenthal said, officials still aren't sure exactly what will be decided on the energy issue this week.