Mayor Marion Barry yesterday appointed Amtrak official Curtis R. McClinton Jr. to replace Ivanhoe Donaldson as deputy mayor for economic development beginning Oct. 24, but strongly hinted that Donaldson will continue to exert considerable influence in the city government--possibly as a paid consultant.

"You don't have to have a position in my city to take on specific tasks," Barry said at a press conference where he announced the major personnel change. "We want to get the job done, and he Donaldson is going to be around."

McClinton, 45, who has extensive experience in government and private enterprise and is a former All-Pro running back for the Kansas City Chiefs, said a prime responsibility will be to implement policies that Donaldson and others already have devised.

Although the administration's new jobs and economic development policies may need some "fine tuning," McClinton said, "As a practitioner, I see a role of implementation as being very critical."

City Council member Charlene Drew Jarvis (D-Ward 4), chairman of the council's Housing and Economic Development Committee, endorsed the selection of McClinton but stressed that he won't be able to deal effectively with Washington businessmen unless he can assert influence over administration policy.

"What is important is that Mr. McClinton be able to speak in the business community for the mayor, that he not be only an implementer but also a policy maker," Jarvis said. "When Mr. Donaldson makes a statement on behalf of the mayor, it's the final word. That's important in business decisions."

McClinton, a resident of Southwest Washington who will receive $63,700 a year as deputy mayor, currently is Amtrak's director of marketing and property managment. He also is a senior associate adviser with Cahill and Associates, a legal and accounting firm, and a senior account executive with Select Line Securities Company Inc.

He played eight successful seasons for the Kansas City Chiefs before retiring from sports in 1970. He was director of the Office of Special Projects in the U.S. Commerce Department's Economic Development Administration between 1977 and 1981, and joined Amtrak in June 1982.

McClinton said yesterday that he shares the mayor's commitment to creating new jobs in Washington, particularly for unemployed youth. He said efforts to stimulate economic development among minorities is also a top priority, "but is one that will be woven in and blended with all other economic activity."

Donaldson, the mayor's top political adviser and friend for the past 23 years, accepted the newly created deputy mayor's post in January with the understanding that he would leave District government by the end of the year.

He recently indicated an interest in returning to private business, perhaps reactivating a consulting firm called First City Corp. that he briefly operated last year. Donaldson, a veteran political organizer, also has had talks with aides to former vice president Walter F. Mondale, a Democratic presidential candidate, and the Rev. Jesse Jackson, who is considering making a bid for the Democratic nomination.

Mayor Richard Hatcher of Gary, Ind., a top adviser to Jackson and long-time friend of Donaldson, said yesterday that so far Donaldson hasn't expressed an intent to work for any presidential candidate.

Donaldson, who did not attend yesterday's press conference, has declined to reveal his plans.