Soviet Premier Nikolai Ryzhkov outlined a long-term national economic strategy today that avoided mention of specific changes in the heavily centralized Soviet system.

Ryzhkov's two-hour speech, delivered during the 27th congress of the Soviet Communist Party, seemed to pull back from some of the more innovative ideas presented last Tuesday by Soviet leader Mikhail Gorbachev.

Gorbachev, in a 5 1/2-hour political report to the congress, gave a boost to several reformist proposals that recently have been given a thorough airing in the Soviet press, including granting local managers significant authority over their own profits and an examination of the pricing system.

But Ryzhkov, a former factory manager named to the Soviet Union's top government job last September, gave a more traditional presentation of the 12th five-year plan, to run from 1986 to 1990.

The plan has been merged with long-term goals for the year 2000 published last fall in draft form and establishing the economic framework for the Gorbachev era.

Ryzhkov's speech today indicated that these economic guidelines, first published last November, had barely changed as they were circulated around the country before being put to the 5,000 congress delegates for final adoption.

One shift, noted by western observers, was a further increase in capital investment -- up to 25 percent, representing an even greater commitment to accelerated growth. The increase in investments reflects Gorbachev's drive to retool the economy, stablilize energy production and improve agricultural production.

Today, Ryzhkov repeated a series of ambitious goals set by the plan -- ranging from such practical steps as raising salaries and boosting annual growth rates from 3.1 to 5 percent, to doubling national income by 2000. He also listed other targets, such as boosting the annual grain harvest to more than 20 percent above recent estimates.

Ryzhkov also indicated several belt-tightening measures that typify Moscow's efforts to save labor and material resources.

He also predicted a cut of about 20 million manual jobs from the work force, shifting them to the service sector.

The speech touched a number of recurring themes of the party congress: blunt criticism of red tape and efficiency and pledges for ambitious increases in the level of technology and the quality of goods, as well as in labor productivity.

Ryzhkov also gave a staunch defense of the centrally planned system, saying "this fundamental principle" will never be abandoned.