new tachometer

[jonny v-max]

does anybody know what the - 12 pole (ob alt)- setting means on a tach. i have a 125hp. ob force on a 88 bayliner.

 

[roscoe]

Re: new tachometer

Outboards have a stator (wire coil assembly) under the flywheel. The flywheel has magnets attached to it. As the flywheel (and magnets) spin over the stator, an electrical current is produced. <br /><br />Each magnet has a "north" and a "south" end, or "pole". So each magnet has 2 poles. <br /><br />If your motor has 5 magnets, it has 10 poles, and needs a tach that is set to read the impulses created by a 10 pole system, or it won't display the correct rpm on the gauge.<br /><br />Your motor has 10 magnets, therefore 20 poles.<br />You need a 20 pole tach.<br />Not many choices available.<br />The tach you are looking for, is made by Teleflex, part number 53743p . It retails for between $45 and $80, depending where you shop.

 

[Realgun]

Re: new tachometer

You cannot use a 12 pole tach. You have to have a 20 pole setting, as Roscoe points out.<br />Do a search on the net and you will find a 20 pole tach or-<br />You can use a tiny tach.

 

[jonny v-max]

Re: new tachometer

thanks roscoe ,just found and read your answer,thanks alot.