Recently got a 73 18 Volvo 279T with original 350 Chris Craft motor (rebuilt) and original Carter carb and exhaust. Trim currently not working so running all the way down. On it now is a Solas 3x 15 5/8 x21LT I get only 4300 RPM and 52 MPH (on speedo) with 3/4 tank of gas and 2 adults. I think I need to go to a lower pitch. But what specific size and brand. There are so so many out there. If anyone has any recommendations or props that may help that I could buy I would appreciate it. Thanks