General Motors Corp. yesterday recalled 800,000 1981 and 1982 Chevrolets to repair exhaust-cleaning catalytic converters that may be deteriorating and detracting from the cars' performance, although not increasing pollution emissions.

The design of the converters, which are used to clean engine exhaust gases as they pass through the exhaust system, are essentially the same as those that were installed in cars manufactured by GM's Pontiac, Oldsmobile, Buick and Cadillac divisions in those years. But those cars are not being recalled because the problem does not seem to be occurring with as much frequency in those models, according to a Chevrolet spokesman.

A General Motors spokesman, however, said the company was continuing to monitor cars made by its other divisions with similarly designed catalytic converters to see if the problem appears elsewhere.

The cars affected are 1981 and 1982 full-size and intermediate Chevrolet models, Camaros and El Camino sedan pick-ups, with V-8 and large V-6 engines. The Chevrolet spokesman said the company has already replaced converters in 157,000 cars made during those two years, but another 800,000 may be affected by the malady. Chevrolet manufactured a total of 2.7 million cars during that period.

The company said that the problem is caused by the fragmentation of the platinum- and palladium-coated beads that fill the catalytic converters and cleanse exhaust gases of hydrocarbons and carbon monoxide as they pass through the converters.

"Over time and operating conditions, they have a tendency to react in the converter, and the edges and crevices in the converter tend to make them fragment," the Chevrolet spokesman explained. The resulting dust-like fragments clog the converters, impeding the passage of exhaust gases and hurting engine performance. "The curious thing about them is, they don't affect tailpipe emissions."