Re: prop
Even though the cuddy is a bit heavier than a closed bow or bow rider, that does seem a tad slow for your set-up. You really need a tach to play around with props because what your ear hears is not necessarily where the engine is supposed to run.
However, switching to a stainless steel prop, 13 X19 uncupped should give you around the same RPM and a few MPH more. See if you can find a used Chrysler stainless prop from 1980 to 1984 on e bay. They are uncupped, fit the Force up to 1990, and are WAY better than the stock aluminum you had on there. Michigan stainless are all cupped and will load the engine down too much unless you drop down in pitch, and when you do that, top speed suffers. Then play with engine height and you may be able to squeak out another mile or two. I suspect the four blade is loading the engine down past its peak horsepower range--but without a tach reading it is just a wild guess.
You need to get the engine turning between 5000-5500 RPM at full throttle.
Now, just as an example, I rebuilt a 125 on a 19 foot Bayliner bass boat. With the stock aluminum prop it turned 6000 RPM and only 40 MPH. With a stock Chrysler stainless 13 X 19 prop it dropped to 5000 and 47 MPH.
I suspect that with the correct prop and engine set-up you should be able to see high 30s in speed.
By the way: Mercury has a stainless prop for its 90 which is 13 X 18 pitch cupped, fits the small 4 inch gearcase, is 15 splines, and MAY fit the Force. It may improve performance. I forget the name of the prop though.
