1975 225 omc one wire alternator conversion

Seabee75

Recruit
Joined
Jun 12, 2012
Messages
2
Hey folks, been lurking here for a long time. Finally decided to create a profile and start posting.

Well, I have a 1975 24' Reinell flybridge cabin boat with a 225 horse omc.

Since I bought the boat a few months ago, the charging system has slowly dwindled. At this point, testing from the rear of the alternator I am putting out about 12.4 volts.

The alternator is a prestolite 45-55 amp I believe, externally regulated. I am thinking I want to convert it to a 10si delco internally regulated. I have found a few online in the 100 amp range for under $120 shipped. I believe just from eyeballing it should have the same bolt pattern, but if not I am sure I can rebuild the mounting bracket to accomodate.

The question is has anyone done this? Again the motor is a 225 horse 307. I priced the regulator at $76 and the alternator at 275-350 for another 55 amp, which does not really interest me. Im thinking money better spent to upgrade and simplify.

Thanks in advance for any insight.
 

cr2k

Captain
Joined
Mar 19, 2009
Messages
3,730
Re: 1975 225 omc one wire alternator conversion

You MUST make sure it is certified for MARINE use, other wise your boat could go Boom!
 

rotaryboots

Recruit
Joined
Jul 23, 2011
Messages
2
Re: 1975 225 omc one wire alternator conversion

It definately can be done, I did it to mine because the stock one doesn't put out nearly enough amps for what I'm running on mine. I used one off a 5.7L Chevy engine from a mercruiser at a boat yard. This alternator was actually a two wire because one ran to the battery, and the other ran to an "alt" light. Another thing, it bolted right up to the stock brakets.
 
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