Quinney, the 2000 U.S. Amateur champion, completed 54 holes at 7-under-par 209.
After darkness suspended play Thursday and rain halted action on Friday, the second and third rounds were both completed Saturday.
Paul Sheehan posted a 2-under 70 to join three-time Nationwide Tour winner Tripp Isenhour in second place at 5-under-par 211. Fran Quinn carded a 3-under 69 to move into fourth place at minus-4.
Quinney was up and down throughout his round. He bogeyed the first, but got that stroke right back with a birdie on two.
The 27-year-old got to 10 under with a birdie on the fourth. However, he tripped to back-to-back bogeys from the sixth to fall to 8 under.
Quinney got one stroke back with a birdie on No. 8, but faltered to a double bogey at nine to slip to minus-7. He traded a birdie for a bogey from the 12th and again from the 15th. Quinney parred each of his last two holes to cling to a two-stroke cushion through three rounds.
Sheehan was 3-over par on his front nine with a birdie, a double bogey and two bogeys. He ran off six straight birdies from the 12th to get to minus-6. Sheehan, however, closed with a bogey on the last to fall two back.
Isenhour, who won the season-opening Panama Championship, was even par for his round through nine holes with two birdies and two bogeys. He climbed to a 7-under with birdies at 15 and 16. Isenhour gave both of those strokes back though as he bogeyed the final two holes.
Johnson Wagner, who won the Louisiana Open last week, managed an even-par 72 to finish at 2-under-par 214. He stands alongside Tom Johnson and Matthew Jones.
Aaron Barber, Craig Bowden, Craig Lile and Michael Long share eighth place and are the final players in red figures at minus-1.