A Rockville foregn car dealership has paid a $1,000 penalty levied by the federal Environmental Protection Agency for tampering with the emission controls of a car it was repairing for a customer.

VOB Datsum Sales on Old Georgetown Road in Rockville, accused by the EOA of setting up a partial bypass of the car's emission control system, is the latest of about a dozen dealerships across tha nation that have paid the civil panalty for similar violations of the Clean Air Act.

VOB's General Manager Bernard Sacks agreed yesterday that his repairmen had tampered with some integral parts of the system, but added that "By doing it, we did improve the quality of emissions on that car - the emissions when it was brought in greater than they should be."

Sacks added that the tinkering with the emission controls was "the only way we could get the car running."

According to the EPA report on the case, David Abramson, who had bought the ccar from VOB, took it in for repairs, because it was running roughly, with the engine surging and sometimes cutting off at high speeds.

Sometime after Abramson got the car back, he drove to Miami, where he is attending law school, and took the car into a dealer there for repairs.

That dealer, who was familar with the EPA rules because a Florida dealer had paid a large penalty for emission system tampering, saw what had happened to Abramson's car and notified the EPA, according to EPA engineer Tom Getz.

The incident took place in 1975, Getz said, but because it was not a clear-cut case, it took the agency about two years to make it case.

Getz added that the agency has stepped up its enforcement of this particular clause of the Clean Air Act that about 30 cased are currently pending. Fines levied in the earlier cases have ranged from $350 to $2,500.