Hollis Alpert, editor of the American Film Institute's 16-month-old magazine, American Film, will be going on a part-time schedule that he says will enable him to "keep control of the magazine, have someone do some of my chores, and be able to write."

In mid-April, Alpert plans to move back to his home on Long Island, commuting to Washington on Tuesdays, Wednesdays and some Thursdays. He is now interviewing applicants for a new job of managing editor of the magazine.

AFI director George Stevens said yesterday that a salary adjustment had not yet been discussed, but Alpert said he will be getting "better than half" of his present salary, which he would not disclose.

"I have an outside income - I write," he said, "so I can afford the reduction. He has completed a novel on "what happened in Jerusalem in 30 A.D.," and is working on a nonfiction book, planning a suspense novel and negotiation on a movie to be made from a previous suspense novel.

A former editor at World magazine, Woman's Day and the New Yorker, Alpert is listed on the Saturday Review masthead as a contributing editor but, he said, "I don't contribute much." He is also a former film critic.

American Film, which comes as part of AFI membership, began with a circulation of 7,200, now has about 41,000 paid circulation, and plans to reach 75,000 by the end of the year.

Alpert said he thought of the part-time schedule when the rent went up on his Foggy Bottom house and he decided that it would be just as easy to commute form Islip airport on Long Island. "George says he'll never let me go - that we're irrevocably tied for life," he said of his negotiations with Stevens.