Would like to know the timing specs of a PA 51 side exhaust and also the open and close timing of the inlet on the crank. Thanks.

The cranks on earlier ones  was  longer duration.

 And the difference in the crank timing makes it run quite differently, not necessarily better or worse, but different. The one unequivocal difference is that the later versions are much less prone to starting backwards. Otherwise, the longer crank duration version runs more evenly through the maneuvers, which might be good or bad depending on the application.

    David's PA51 system (long crank duration version) had/has the most static thrust of any otherwise working system we have tested, much more than the PA61, PA75, or RO-Jett 61, at least in competitive trim. It's at absolutely full tilt boogie on the ground, fearsome on takeoffs because the acceleration is so high, about like an electric.

      Brett