Lewis Rollo beat Thruxton specialist Alex Olsen to pole by 0.260secs as the latter crashed out on his final lap.
Rollo set a best lap time of 1min 22.752s on his third of seven laps, which went unbeaten even as the track began to dry after a wet start.
Olsen held onto second and will start alongside Billy McConnell, as points leader Dan Linfoot heads row two, with Joe Talbot next to him in fifth place.
Pirelli National Superstock with Santander Consumer Finance, qualifying result:
1. Lewis Rollo (IN Competition/Aprilia) 1min 22.752s
2. Alex Olsen (Cumins by Team IWR Honda) +0.260s
3. Billy McConnell (C&L Fairburn Properties Jackson Racing) +0.493s
4. Dan Linfoot (Optimum Bikes Racing Ltd) +0.522s
5. Joe Talbot (JR Performance Racing) +0.731s