Excerpts from April, 1957 issue of MECHANIX ILLUSTRATED magazine
... Oliver has entered the large horsepower field with a 35-hp twin which includes several unique features. One of these is a completely detachable powerhead. In a matter of minutes the powerhead and lower unit can be taken apart to offer easier portability and storage and lessen the possibility of theft.
Both Oliver and Scott-Atwater feature a novel lower unit clutch arrangement. Rather than having a drive shaft pinion gear mesh with either of two bevel gears actuated by a horizontally operating dog clutch on the propeller shaft for forward and reversing action, these two manufacturers position the dog clutch vertically between two pinions on the driveshaft. The shift mechanism lifts or lowers the two gears into contact with a single propeller shaft bevel gear. This results in elimination of several shift train parts and a slimming of the lower unit. The vertical rather than horizontal type clutch mechanism permits easier shifting with less wear on the gears. However, the design does have the drawback of creating greater steering torque.
The Oliver, which displaces 42 cubic inches, is equipped with a 12-volt electrical system complete with battery and generator. Several features once found on the now defunct Martin motors, automotive intake poppet valves and a front of the motor angle adjustment feature, are found on the new 35. The poppet valves add to the quiet features of the motor and offer improved fuel vapor flow to cylinders at low speed and during acceleration, though engineering-wise, their application would appear to be a step away from two-cycle simplicity of design...