porp question

[vegas_storms]

Hello,
I have a 89 172 cobalt with a 4.3L mercruiser 175(with I believe an Alpha unit, can not read serial numbers). This boat was only ever used at an elevation of 6500ft with a 17 degree prop, will this allow my rpm's to go up beyond what the manufacture designed it for at an elevation of 2500ft? Do I need a 19 or 21 degree prop? Hope this makes sense, it's all new to me.
Just want to make sure before I take it out and see what it can do.

Thanks for the help

P.s. Does anyone know what the max rpm's should be with this motor or where I could get this information.

 

[WillyBWright]

Re: prop question

Re: prop question

At an elevation of 6500, the carb might have been rejetted and the outdrive gear ratio might have been changed. You'll need to look into those, especially the rejetting. Gear ratios can be compensated for with prop pitch. Right now any advice would be contingent on what might have been done relating to high elevation. Til then, Full Throttle is not carved in granite. You have our permission to to use less throttle to keep it in the recommended RPM limits.