Oddsmaker Sean Van Patten of Las Vegas Sports Consultants said the firm gave that line after watching New Orleans struggle to beat the Minnesota Vikings in the NFC Championship Game Sunday night. Las Vegas Sports Consultants provides betting lines for roughly 90 percent of sports books in Nevada.
"The big factor here is that Indy has been there," Van Patten said. "The experience factor is such a huge thing when it comes to the Super Bowl."
Manning and the Colts won the Super Bowl in 2007 over the Chicago Bears.
Patten said oddsmakers like that Indianapolis has succeeded against two top NFL defenses in consecutive games. The top-seeded Colts beat the New York Jets 30-17 Sunday in the AFC championship.
Indianapolis was a 4½-point favorite in the Glantz-Culver line, with the over-under at 55½ points.
Sports books gave Indianapolis 8-1 odds to win the Super Bowl at the start of the season, compared with 18-1 for New Orleans.
"I think the Saints are very fortunate to be in there," said Jay Kornegay, executive director of the race and sports book at the Las Vegas Hilton. "To get five turnovers at home and having to go to overtime to win it, I don't think they were playing that well."
New Orleans outlasted Minnesota 31-28 in overtime, even though the Vikings gained 218 more yards and had nearly twice as many first downs as the Saints.
Jay Rood, race and sports book director for casino operator MGM Mirage, said bettors began favoring Indianapolis soon after New Orleans won and the odds were posted.
Rood said that was because the Colts have been consistent all year, while Saints bettors who lost Sunday because New Orleans didn't cover the spread didn't want to take the team again so soon.
"They don't usually come right back on the team that just burned them on a bet," Rood said.