The Federal Trade Commission yesterday voted, 3-to-1, to allow former chairman Miles W. Kirkpatrick to continue participating in a rule-making proceeding he's been participating in for two years.

Although chairman Michael Pertschuk was one of those voting to allow Kirkpatrick to continue, he served notice that in the future, he will be very tough on "clearance" requests. ". . . public trust and confidence in the integrity of our substantive decision-making cannot be achieved unless the public is convinced that no former member or employee who practices before this agency possesses an improper advantage."

Kirkpatrick, who left the FTC in February 1973, has been representing the Mobile Home Manufacturers Association in proceedings aimed at developing an industry-wide rule that would outline mobile home manufacturers' responsibilities in warranty-related claims from mobile home buyers.

Kirkpatrick suggested to the commission in a letter in February 1975 that - based on his reading of the agency's rules - he did not need to ask for "clearance" to participate in the rule making but was giving them the chance to disagree. Because he had "informal indications from the staff" that his representation presented no problems, and because he never got a formal reply from the commission, he began to represent the mobile home association, as did another of his partners in the law firm of Morgan, Lewis & Bockius. The partner, Caswell O. Hobbs III, was Kirkpatrick's assistant at the commission. It turned out the matter had never reached the commission; a staff report on it had been lost.

The question of Kirkpatrick's participation came up recently because of a Freedom of Information Act request and the matter was sent to the commission again.

Yesterday, commission member David A. Clanton argued strongly for denying Kirkpatrick's future participation in the proceeding to maintain the "integrity of the rules" despite the time elapsed, the extent of participation, and the commission's own laxness.

Commissioners Elizabeth Hanford Dole and Paul Rand Dixon argued strongly on the other side, suggesting that Kirkpatrick had not had access to any information while at the commission which could benefit him or his client in the proceeding. Dixon raised the possibility that if they disqualified him now, the two-year-old proceeding would have to be started anew. "We ought to face head-on what attorneys can do in the future," Dixon said. With a too-strict interpretation of the rules, attorneys who leave the commission will only be able to "sell apples and pencils," he said. "They won't be able to practice law."

Pertschuk said he voted for Kirkpatrick's continued participation because he was "troubled by the possibility that the two-year delay in considering the matter could be the deciding factor. ". . . There is little doubt that, if these requests had been considered in timely fashion, the requests would have been granted," he said.