The multiple TT winner set the fastest time of the week in the Classic event on his Yamaha Superbike at 125.49mph.
Anglesey's Barry Lee Evans topped the Senior MGP board while home rider Michael Evans moved to the top of the Junior leaderboard.
Michael Evans' 119.228mph lap was the fastest Manx Grand Prix time so far.
Darryl Field leads the Newcomers' section after a lap of 115.09mph.
The session was cut short as mist fell on the mountain section with qualifying to continue on Friday evening with the first racing on Saturday.

The UK stage of the race comes to the city on 7 July.
Cycling enthusiast Rad Wagon is recruiting people to knit 3,000 miniature "Tour jerseys" and wool-covered bicycle wheels.
Schools and knitting groups have already offered to start knitting and the council was "interested", he said.
A similar "mini-jersey" idea is being promoted by Harrogate Borough Council for the Yorkshire stage of the race.
The public response to that was so overwhelming the council had to ask people not to send any more knitting to them.
"It's a bit copycat but we can do so much more," Mr Wagon said.
"The city's well-known for its knitters and 'yarn bombers' who cover everything from bikes to trees to lamp-posts. It's 'very Cambridge'.
"I think knitting is in Cambridge's DNA," he added.
Mr Wagon, a cycling skills and bicycle maintenance trainer from Outspoken Training in the city, said he was a fan not only of the Tour de France, but the cultural activities surrounding it.
"It isn't just a bike race. Its history is all about promoting your town and region and that's something we can do.
"The world's eyes will be on us and it's a chance for us to show that Cambridge can do things slightly differently, and perhaps slightly oddly," he said.
A knitting shop owner has offered to give knitting lessons and collect the tiny pullovers, Mr Wagon said.
A cycle shop in the city has also offered a collection of battered wheels which Mr Wagon hopes can also be turned into knitted decorations.
He said he was discussing suitable places his knitted bunting might go, with the city council.

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The 40-year-old won Olympic heptathlon bronze for Britain in 2004 and has been upgraded to two more bronze medals from 2008 after retrospective drug tests.
All world records set before 2005 could be rewritten under a new proposal from European Athletics, after the sport's latest doping scandal.
Sotherton said tweaking events would create "a new slate" and new records.
She said: "Could we go back to yards or run 101m instead of 100m?
"We all know that some of the records are completely out there. But not all of those records were achieved by people who cheated.
"Scrapping those records is unfair on those athletes. And what about my pre-2005 performances? Did they happen? Does this apply to national records too?"
Sotherton referred to the IAAF's decision to remodel the men's javelin in 1986.
Changes were made to the javelin's design because of increasingly frequent flat landings. All existing records were reset after the change, but not erased.
"I am open to the discussion - for the greater good of the sport it's a good thing," she added.
New Zealand racer Bruce Anstey continued to set the pace in the fourth qualifying session at the Isle of Man Festival of Motorcycling.
[NEXT_CONCEPT]
A man who admits he "cannot knit a stitch" is hoping to cover the streets of Cambridge with knitted bunting and wool artwork during the Tour de France.
[NEXT_CONCEPT]
Kelly Sotherton says athletics chiefs should consider tweaking events rather than rewriting existing world records.