Mercury Tacho

[Deep Blue]

I have a tacho which I am going to fit in the week, the only problem i have is that on the back there are 2 settings, 1 is for a 12pole alternator and the other is for a 10 pole alternator. The engine i have is an early 80's merc 80hp PTT.
Any idea which setting it should be on?? 12/10 pole
Regards

[Deep Blue]

It also states "5 pulse/10 pole or 6 pulse/12 pole"
any help appreciated.

[steedthrust]

http://www.tflx.com/obtachtrad.html might help.

[jace]

Should be set to 12, most Merc/Mariner use this setting.