Quoting page 2.4 in Bob's AGK book "L Shaped flyweights are geared to the engine so they rotate in a horizontal plane"

I was a little surprised to read that they are geared to the engine, I would of thought that they were geared to the propeller shaft?

I guess my question comes down to does Crankshaft (engine) RPM = Propeller RPM?

My understanding was that with a CSU you could manipulate engine RPM and torque to achieve a desired blade angle and prop RPM.

There are some aircraft piston engines that are geared to the propeller i.e. the engine turns faster than the propeller. However they are rare in small GA aircraft. In any case a CSU does not require the engine to be geared to the prop so in most cases the engine RPM is the same as the propeller RPM. The propeller is simply bolted onto the end of the crankshaft. The propeller governor works by changing the actual pitch of the propeller blades.

For a given throttle position, if the propeller blades move into a finer pitch, the propeller becomes easier to turn and the engine RPM [along with the propeller RPM] increase.

For a given throttle position, if the propeller blades move into a coarser pitch, the propeller becomes harder to turn and the engine RPM [along with the propeller RPM] decrease.