Originally Posted by TRBenj
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.
I didn't not mention previously but it does have the 454 with slot. You are correct on rpms. They are right at 4600rpms.
I had planned to put the other prop on before the end of this past summer to see what the rpms and speed were but just didn't get to it. I do think it is a 19 or 20.