70 hp johnson alternator

[minocqa]

hi<br />i have 1976 70 hp johnson<br />does it have a 2 pole or 4 pole alternator on it i want to hook up a tach but i heard that some tachometers will only read half the rpms with a 2 pole alternator is that true?<br />any help would be appreciated<br />thanks<br />Don

 

[Paul Moir]

Re: 70 hp johnson alternator

Your outboard has a 6 pole alternator (12 pulses per revolution). You need to use an outboard tach that has a '6' position. Most have a little switch on the back that selects 4, 5, or 6 poles and you simply need to set it correctly.<br /><br />If you set it incorrectly, the tach will read wrong.

 

[minocqa]

Re: 70 hp johnson alternator

thank you