[Trevor]

It is suggested that the torsional vibrations involved are transmitted to the camshafts and valve gear. All of this is driven by a long flexible belt and has inherent self induced torsional loading problems, far exceeding anything possibly transferred from the crankshaft. There will not be any attributable effect on ignition, or valve timing, much less that confined to the rear cylinders.

A very strange document allegedly from GM with attached text, which refers particularly to making up a special grade of rubber for the Corvair. The publisher is Dale Manufacturing, Salem, Oregon. This data should be treated as simply advertising blurb, which demonstrates how fallible this stuff can be, and is particularly unsuitable as a learning text.

There is no mention of a very important factor involved, i.e. the load driven by the pulley via a belt, which is in itself an efficient flexible coupling. The weight of the outer portion of the pulley is insignificant as a torsional load, when compared with the total reciprocating weight driving the centre section. The driven parasitic accessories, therefore form the required major torsional resistance.