OMC stringer gear ratio for 3.8

[greentahoe]

I'm replacing my stringer upper gearcase on a 3.8 with one from a 5.7. The ratios are different in the two applications, but I can get the replacement gearcase faster and cheaper than replacing my destroyed gears in my old gearcase. My question is this; I have a stainless prop and a couple of aluminum props for my boat, in order to get the boat up and running as quickly as possible can I cut some of the aluminum off one of the aluminum props to reduce the surface area and thereby reduce the amount of torque on my engine? I would cut the material from the trailing edge of the prop so I don't interfere with the leading edge. When I have more time I would have the stainless prop repitched, how much should I have it reduced for starters? The boat is a 1984 23' Proline walkaround cuddy. I'm not interested in going faster, just in getting around to where the fish are

 

[KaGee]

Re: OMC stringer gear ratio for 3.8

Gear ratio on the 3.8 is supposed to be 21:20.
The 5.7 upper has a ratio of 21:16. Both have the same lower.

I do not understand this correctly, whether or not your prop will not spin as fast or faster with the 5.7 ratio.

DO NOT grind your prop. You can try changing prop pitch to comepensate, hopefully someone with a better understanding can help you there.