Sorry, something to me isnt adding up on my setup and thought I would get a few opinions. I got a 1985 3.0 mercruiser 140hp with a 1.98 alpha. I have a well used and dinged up 17p 3 blade prop. Boat is a 16.5' fiberglass runabout. From what I have read, my optimum WOT RPM's should be roughly 4400-4800. I am spinning 4100 trimmed perfect and getting to 43mph. I cant believe I should be running a 16p or 15p prop with this setup. I am starting to think my tach is off, but really have no way to test it. I would love to hear some ideas. I have had the boat a week now and havent really check much, compression was solid at approx 130 across the board, fuel was 1.5 yrs old, mixed it with new and seafoam. idles and runs fantastic so I dont think there is a fuel issue for not getting rpms, I havent check timing yet. anyway, let me know what your thinking and what I should look at if anything at all!
