Tach reading wrong... or motor not right???

[cdoliver]

Hi, I just put a new faria tach on my boat. The motor has been rebuilt and is running great. I am satisfied with how it is running (1979 johnny 115) This Faria tach has 6 selectable positions. I turned it to position 6 and at WOT it reads 3600RPMS. So I'm thinking that can't be right, so I moved it to position 5. Now I'm getting 6500RPMS... That can't be right... My boat is a 1980 Skeeter Wrangler 16ft. WOT with GPS says 44 MPH. It weighs around 1100-1200 light load. Here are what the instructions say about what position.
I'm pretty sure I should be on setting 5. But 3600 rpms doesn't sound even close. The old tach read around 5000 before it broke from old age.

OB ALT SWITCH SETTING.
1 - 4 POLE
2 - 6 POLE
3 - 8 POLE
4 - 10 POLE
5 - 12 POLE
SLIGHTLY DEPRESS WHILE TURNING

Any Ideas??? I'm a little worried about this. Thanks

 

[cdoliver]

Re: Tach reading wrong... or motor not right???

Correction: On the #5 setting I'm reading 6000-6100. I also bumped from 100 to 115 hp in the rebuild. Is it possible that the 15 hp is making it rev up that much higher with the same prop??? Thanks for your answers.