1969 Mercruiser 2.5L 120 HP alternator upgrade

[Catfishcabin]

Some fairly certain my alternator is going out I'm only getting about 13 amps out of it and was curious if this model will fit it would be nice to have the extra amperage to make sure my two batteries stay well charged during my longer trips. This particular alternator says the size would fit but it doesn't have my year everything starts later. Thank you

https://www.powerparts360.com/after...0wlRaMo563xrRYeCcDFritXZqT-2Vb0bTgaAuEr8P8HAQ

 

[Bt Doctur]

that should be a direct bolt up.maybe just a change of belt but given your age and wiring a "Single wire" would work better

 

[Catfishcabin]

So I can convert to a single wire?

 

[Bt Doctur]

Yep, only 1 orange wire and 1 black wire. Alt is self exciting at about 1000 rpm To install a 3 wire you need a "sense and excite" circuit. 1 wire is constant 12v battery and the excite is a switched 12v to turn on the alt

 

[Catfishcabin]

So what are pros and cons?

 

[Bt Doctur]

What is the wiring now for your old alt, is it still the external regulator or a later model internal

 

[Catfishcabin]

I believe late model internal. 3 wire

 

[Bt Doctur]

Then it will be plug and play with the alt depicted