Al Unser Jr. raced to his second Indy-car victory in eight days as Mario Andretti's engine burst into flames and stopped while he was leading the Budweiser Cleveland Grand Prix with three laps remaining yesterday.

Andretti led most of the way after front-row starters Bobby Rahal and Danny Sullivan retired early with mechanical problems.

Andretti lost third gear late in the race but still was ahead of Unser by 35.9 seconds on lap 84 of the 88-lap event. However, his Lola slowed suddenly, with flames coming from the engine compartment.

Unser, the son of three-time Indianapolis 500 winner and 1983 Cleveland winner Al Unser, roared past as Andretti scrambled safely from his car.

"I don't want to wish bad luck on Mario, but it sure is a lot easier to win when he's not there," Unser said

Unser won the U.S. Grand Prix at the New Jersey Meadowlands last Sunday.. . .

Jeff Andretti, the son of Mario Andretti, won a Super Vee Championship event following the Cleveland Grand Prix. Andretti, driving an Electrolux Ralt RT-5, had a winning margin of 9.30 seconds . . .

In Le Castellet, France, Brazil's Nelson Piquet, jumping into a back-up Brabham-BMW moments before the start, won the French Grand Prix, his first victory in more than a year.

His winning time was 1 hour 31 minutes 46.266 seconds at an average 125.099 mph . . .

Willy T. Ribbs, driving a Mercury Capri, claimed his third Trans Am victory of the season at Summit Point (W.Va.) Raceway, as he held off teammate Wally Dallenbach Jr.

Ribbs finished in 1:05:14.9, 14.5 seconds ahead of Dallenbach who also drove a Capri.

Third was Tom Gloy, also in a Mercury Capri.