Prop sync and noise in twins

Dudley Henriques writes:

We had a Cessna 337 on our line for charter use at one time. It had a sync
gauge. Strangely enough, whenever I had occasion to fly this bird I always
ended up syncing the props by ear. You could easily feel if one of them was
out even by a small amount of RPM.

Logically the smallest differences would also be the most annoying, since they
would result in such slow variations. And in theory you should be able to
eliminate them by adjusting RPM manually. But since the Baron has a prop sync
switch it occurred to me that perhaps the RPM levers aren't precise enough to
make it easy to sync the props (?).

I'm still not clear on whether or not this switch actually moves the prop
levers or what. If it does, it sounds expensive, since it needs an actuator
or servo in the cockpit or along the linkage. If it doesn't, it means that
some of the engine control positions might not accurately reflect the actual
engine settings and that engine settings might not obey the control movements
if prop sync is operating.

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