So, you don’t know a carburetor from a crankshaft or Tony Kanaan from Tony Stewart?

If so, you probably don’t know the Indianapolis 500 is Sunday, let alone care who wins the race.

Even the most disinterested among our readers, though, could develop a rooting interest in J.R. Hildebrand, who qualified 18th at the Brickyard on Sunday.

Hildebrand, 24, a Sausalito native, is a lifelong 49ers fan who drives for Panther Racing, a 15-year-old IRL team that counts Jim Harbaugh as a founding partner and one of five current co-owners. Hildebrand drives the No. 4 car, Harbaugh’s jersey number for most of his 15-year NFL career. I spoke to Hildebrand this week for a Sunday story I’m writing on Harbaugh and his connection to open-wheel racing.

Hildebrand visited Harbaugh and the 49ers during last year’s training camp and got to know kicker David Akers (big gearhead, he said) and tight end Delanie Walker (classic car enthusiast), but didn’t venture near imposing linebacker Patrick Willis.

“I didn’t even get within 15 feet of that dude,” Hildebrand said, laughing.

Hildebrand also got to know Harbaugh – the two had never met until Hildebrand’s visit.

“In five minutes, you can tell that he’d be the type of guy you’d like to play for,” said Hildebrand, a former baseball player at Redwood High in Larkspur. “You can see that he had a real connection with the guys that play under him. As a player I’m sure you kind of look at him like a peer, a guy you wouldn’t want to disappoint. That was definitely cool to have that opportunity last year.”

Hildebrand also talked open-wheel racing with Harbaugh, who developed a passion for the sport when he played for the Indianapolis Colts from 1994-97. Harbaugh has been a regular at the race since 1994, although he won’t be there Sunday, and was in the pits two years ago when the late Dan Wheldon finished second for Panther. Harbaugh has called the Indianapolis 500 “better than Christmas.”

“There’s still a piece of his heart that’s in Indianapolis with the race team,” Hildebrand said.

Plenty of racing fans’ hearts will be with Hildebrand on Sunday after his hard-to-watch second-place finish in his first Indianapolis 500 last year. Hildebrand had the lead before crashing into the retaining wall on the final turn.

Hildebrand is now looking for redemption Sunday. In some ways, his story mirrors that of Alex Smith, who was also having the ride of his life before coming up just short last season.

Like any legit 49ers fan, Hildebrand has an opinion on Smith, who won him over last year.

“I’m excited for him,” Hildebrand said. “In the past, it was always up in the air and you never knew if he was going to come through. Last year, man, you watched that playoff game against the Saints and you say, wow, there’s a reason why that guy was a No. 1 pick. For me, that was all I needed to see.”