Chrsyler Corp. has acknowledged a design problem in 1.3 million cars built in the past two years but does not consider the defect serious enough to authorize recalls.

The Detroit Free Press reported Sunday that the defect involves carburetors on 1975, 1976 and 1977 Valiants. Darts, Aspens and Volares with 318-cubic-inch V-3 engines or 225-cubic-inch six-cylinder engines. The problem reportedly has caused frequent stalling, mostly when the engine is cold.

The Free Press said the No. 3 automaker discovered the problem a year ago and made necessary assembly line adjustments last spring. The newspaper said some cars have been fixed without charge under a selective repair program. But the trouble was not publicized, and the company said a recall was not necessary because "these problems do not present an unreasonable risk to traffic safety."

However, Clarke Harper, an investigator for the National Highway Transportation safety Administration, said the defect has been blamed for 29 injuries, the Free Press said. Nine lawsuits also have reportedly been filed because of the stalling.

Chrysler issued a statement saying the stalling was common among all cars carrying newer emission control equipment. The company said dealerships have received special kits and instructions for fixing the stalling problem.