Richard Petty stormed back into the lead after a two-hour rain delay and scored an overpowering 17.7 second victory over Darrell Waltrip in today's Firecracker 400 Grand National stock car race.

Petty'sDodge had moved to a sizable advantage at the halfway point when thundershowers doused Daytona International Speedway. The race was redflagged on the 82d of 160 circuits around the 2 1/2-mile trioval.

Petty drove through the pack quickly after the restart and left his challengers hopelessly behind.

Petty said he went out on the tracj after the rain delay looking for a fast car to draft.

He found Bobby Allison, who was running fast but was out of contention because of earlier engine problems, stuck on his rear bumper as they whipped around the speedway, and picked up his 185th career NASCAR victory.

"I got with Allison and pulled away from them all," said Petty with a grin after winning $23,075.

The three women starters, Lella Lombardi of Italy, Christine Beckers of Belgium and Janet Guthrie, failed to finish the race and were among the first to drop out.

Third was Benny Parsons. trailing oil smoke at the end as he was at the start. Seven drivers were still on the leap lap at the finish, including David Pearson, A. J. Foyt, Donnie Allison and Buddy Baker.