Gear Ratio information

[jsta_rebel]

I have an IT 40 motorsailer powered by a lehman 120 HP with a Borg Warner Velvet Drive transmission. My Prop is 26" x 24 Pitch on a 2" shaft. I am cruising the Caribbean and have had transmission problems. There are no markings on the unit, and I need to know what the gear reduction ratio is. Can anyone help?

Thank You!!

jsta_rebel

 

[Roger Long]

If that engine doesn't have decompression levers, you could loosen the injectors to remove the compression. Then put a piece of tape or other mark on the flywheel and one on the coupling. Turn the flywheel by hand and count the turns until the coupling has gone around once.

You might try bumping the starter with the fuel shut off first. You might get close enough that way if you watch it carefully. Just punch the button to kick it a few degrees at a time.