V drive gear ratio's

[stump]

I have been trying to figgure out what over drive is in my casale without taking it apart .Here's what i did.Placed a mark on engine drive shaft at 12 o clock position,mounted a degree wheel on prop shaft and lined 0 with a pointer,rotated engine shaft 1 full turn back to it's mark.Degree wheel read 63 degrees''360+63''.Then I divided 63 by 360% and came up with 17.5.So i'm figguring I have 17.5% overdrive gears in the box.I figgure with shaft backlash this might corrolate to 18% gears.Does this sound correct? Engine produces 502 horsepower what pitch 2 blade prop would ya'll recommend I can run up to a 12 inch diameter nothing larger.Thanks for the recommendations.

[Rexone]

Sounds right to me on the gear figurin. Really would have to know more about boat to make any recommendation on a prop, but assuming it's a flat of some kind, a good place to start would be 11.5" diameter...less power you can get away with a little more diameter. too much diameter will torque the boat too much. keep in mind different kinds of props react different too and no 2 are alike. I'd start with 11.5 x 15 probably as a good starting point. You can always shave the diameter a bit if it manhandles the boat but it shouldn't be bad with 500 hp.

[stump]

Mike boat is a 79 mandella short deck 17 1/2 ft casale v drive also has a velvet drive trans.
Boat currently has a 3 blade 12x15 lh on it and rear of boat jumps out of water and prop cavatates.I'm kinda thinkin a 2 blade might make it take a set better.This is a lake hot rod ,just for fun! thanks ,i'm new to all this stuff.

[V-Drive Tom]

Stump, If you are correct about your gear ratio,(18%) then a 15 pitch is all you will be able to pull.(The 16 would keep your RPM down to much) The 11 1/2 diameter is good. IF you would like to buy a NEW prop, I will guarantee that you have the right prop on your boat. Call me. :cool: TOM..530-885-0531. PS, If you would like help over the phone with taking your v-drive apart, just call. :) Menkens V-Drive..TOM..

[stump]

Thanks Tom I'm saving up for a new prop now.I have to let my better half get over what i spent on this project up to this point .Bought the boat then had to build a new engine ,new block crank heads intake the whole kit an kaboodle.My fun tickets are down so now i'll squirrle my allowance and when i get enough i'll give you a call,thanks a bunch for the help.