tach set up help

[powerwagon360]

On the back of my omc tack it has a arow that you can point to diferent #s. i have a 90hp v4 do i put the tack on 4? like on a automotive tach?

 

[powerwagon360]

Re: tach set up help

ok i looked around and found out that the number of poles in the alternator has to do with the seting on the back. so how do i know how many pole my alt. is?