Ace Adler and the Pendulum of Doom - John H. Matthews

Twelve-year-old Ace Adler is counting down the minutes until the end of the school year. It's just a little shocking when he counts them more than once. Ace learns that being a time traveler is useful when it comes to redoing class projects and stopping birthday cakes from getting destroyed. But it's way less fun when an inventor from the 1600's shows up to tell him that the giant pendulum clock which controls all time is broken.

And Ace is the only one who can fix it.

With the help of his best friend Alexis-and maybe his dad, if he can stop talking about the dreaded upcoming camping trip-Ace unravels clues to fix the clock and prevent time from stopping forever.