1973 evinrude 85hp gear ratio

[lindsey]

Hello trying to find out what gear ratio my 1973 starflight 85 rude has? I tried a search without any luck. Thanks for any replies

 

[ezeke]

Re: 1973 evinrude 85hp gear ratio

Propeller gear ratio as expressed in the OMC factory manuals is 13:26 or .50.

 

[lindsey]

Re: 1973 evinrude 85hp gear ratio

I tried to use that ratio in a prop calc but it doesnt seem right im not familiar with ratios.

 

[ezeke]

Re: 1973 evinrude 85hp gear ratio

Most of the canned theoretical formulae use the engine to prop ratio rather than prop to engine ratio, so you would need to enter 2 on following one as an example.

http://go-fast.com/Prop_Slip_Calculator.htm