stevej and Bruce, that engine is a Villiers 'Torquemaster'.
My Dad had the same engine (with the glass bowl fuel filter) on a Pace lawnmower in 1959. It was (if my memory serves me correctly) 98cc and extremely reliable. In fact we used to mow the lawn in the morning and put the motor on our (very rough) go-kart for an afternoons racing at the old Boondall drive-in!!
Great days!
