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The right and left turning versions could be converted into the other version by simply changing a single gear in the reduction gear section.
There is a little more to it than that. Given to me by an Allison overhaul shop many years ago.The right and left turning versions could be converted into the other version by simply changing a single gear in the reduction gear section.
But still, only one part has to be changed in the engine. Which is what Ward Duncan said
(3) One spur gear train from the flexible member of the vibration damper drives the accessory housing camshaft drive mechanism and the supercharger. In right hand rotation engines, this gear train is geared directly to the damper. In left hand rotation engines, an idler gear is used between the gear train and the damper. A second gear train is used to drive the generator, vacuum pump, the fuel pump, and the coolant pump. In right hand rotation engines, this gear train is driven through an idler gear from the damper, while in left hand rotation engines the train is driven directly from the damper.
The right hand bank as viewed from the distributor end (rear of the engine) must have several spark plug leads interchanged because the cam lobes are backwards. It works out the same for the left-hand bank, somehow ... no left bank changes to the firing order
Easy to convert an E to an F. You need an E-series front case and the bearings and gears thaht go in it. Simple change.
A less well-known difference, the middle two spark plug wires have to be swapped for a left-turn engine.I believe there was more to it than that.
The camshafts had to be flipped end to end, and maybe the crankshaft too.
The engine itself actually rotate in the opposite direction - it was designed to do that..
The accessories section (including the supercharger) could not work in reverse rotation, without the expense of building opposite hand units, so an idler gear was placed in the accessories gear drive.