Nemechek, driving the Chip Ganassi Racing No. 42 Chevy that Tyler Reddick drove to the victory at Kentucky last fall, and that Kyle Larson has won the two most recent NXS races with, posted a best speed of 180.886 mph to lead all drivers.
34 cars participated in the practice, Busch completing the most laps at 27, JJ Yeley completed the fewest at three.
A late run in the second practice put Ty Majeski up front in the Roush Fenway Racing No. 60 during the second practice at 181.714 mph, and he was followed by Bell at 181.616 mph.
In third was Hemric at 180.562 mph, and fourth was Busch at 179.970 mph. Tifft rounded out the top five at 179.856 mph.
There was a brief pause in the action after Ross Chastain got into the wall.
Dillon completed the most laps this session with 40, while Josh Reaume turned the fewest with two.
38 cars took part in this practice, Reaume’s No. 79 was the slowest car on track at 154.750 mph.
Qualifying for the ALSCO 300 will be Friday, July 13, at 5:05 p.m. ET, with the race itself set to begin around 8 p.m. ET, with TV coverage on NBCSN.