McLean dominated from pole on the McAdoo Kawasaki and was never seriously troubled as he pulled clear to win by over nine seconds in the race, which was delayed until later in the day after Michael Sweeney crashed at the end of lap two.
Superbike winner Mike Browne (Burrows Engineering/RK Racing Yamaha) ran with McLean in the early stages before eventually dropping back and settling for the runner-up spot.
It was Tobermore man McLean’s second win of the day after he was a runaway winner in the Supertwin race.
Magherafelt’s Paul Jordan was a lonely third on the PreZ Racing Yamaha, 25.3s behind McLean, with Darryl Tweed taking fourth on Stanley Stewart’s Yamaha R6.
Sweeney was absent from the race after damaging his Yamaha following his crash earlier.
The Skerries man walked away from the incident and was able to compete in the Open Superbike race, finishing third.