Since raising the compression of a 20 year old engine is effectively impossible for nearly everyone, the discussion must turn to more mundane approaches such as glow time, battery voltage, oil viscosity, starter condition...........etc.

I will state, however, that the new valves on the SD did absolutely raise the compression for start and I'd seriously advise anyone to consider it.

The SD would start to struggle at 15°F. with 10-15 second crank times.

Now, it starts in one second at 0°F.