Originally Posted by jeff shelton
My 1990 190 with powerslot trans has a ACME 4blade 14x20. Top Speed right at 50mph. I'm not sure what would have been installed from the factory.
I do have an additional 3 blade that came with the boat but I'm not sure of the size. The dealer that I boat the boat from said that they installed the new 4 blade because the boat was turning 5600rpms with the 3 blade. I have yet to run the prop to confirm rpms and speed.
Those numbers make sense. The 13x14 Acmes work well on the 1:1 big blocks. Multiply that 14" of pitch by your 1.5 reduction and youre at 21"... so 20" isnt too far off. How many RPM's do you pull that prop? My guess is 4600 +/-? 50mph seems about right for a 330hp BBC in a 19' ski boat. Thats where most of the 454 Barefoot Nautiques and Ski Nautiques run.
5600rpm would imply that the other prop was a pretty gross mismatch for your powertrain. Probably in the 13x14 to 13x16 range? Either that or the 5600rpm claim is likely incorrect.