The original intrinsic angular
momentum of Venus was lost due to tidal locking and its' current situation
may be a resonance effect.

Speaking of that, do you know how to calculate the spin-down time, or the
1/e rotation frequency diminution time, for a planet as the result of the
tidal drag from a single other body? I've been looking for this equation,
but I haven't found it, and I've been using one I put together on
assumptions that might not be right.

Jerry Abbott