1974 omc alternater

[bgillen]

Hello, My 1974 255hp OMC calls for part# 383443 34 amp alternator assembly which has two insulated posts. at one post is the field connection to the external voltage reg. a yellow wire. At the other insulated post there is a batt. lead with a inline 60 amp fuse. OMC replaced the 383443 with the 985964 34 amp alternator which has one insulated post marked BAT and one non-insulated post on the side. I assume this is where I should connect the yellow voltage reg. wire? OR is the voltage reg. built into 985964 alternator, and if so should I connect the side non-insulated post to engine ground (what size wire to use?)?

 

[Howard Sterndrive]

Re: 1974 omc alternater

lots of sellers online have a 985964 replacement which is a Delco unit with an internal regulator. If you want to make make it even simpler, you can get a "1 wire" alternator which is internally excited and only requires the 60 amp wire connection. The regulator and other connections can be discarded or taped off.

Unless you have a dual batt isolator, best just to go 1-wire type. If you have an ammeter in the dash, you can replace it with a voltmeter (which provides much more useful info)
I suspect the one you got is deleting the ammeter shunt circuit or something, but a pic might help us if you are commited to it.

External regulators are museum pieces these days, I have to suppose the new one is internally regulated but who knows.
The Field wire would have to connect to an insulated terminal on any externally regulated unit. It sure can't hook to the frame or casing of the alternator - that's grounding it and that won't work at all.

 

[Howard Sterndrive]

Re: 1974 omc alternater

is this the unit? the F terminal is insulated on this one.

this pic might help if replacement looks like this:

those are just refernce pics from what I can tell - if you order an Arco replacement now, it appears you get a 1 wire Delco and throw the regulator away.

 

[bgillen]

Re: 1974 omc alternater

Thanks Howard, the pic is of the old one. I have attached a pic of new one. So I just hook the bat lead and discard the old volt reg and seal the wire that goes to the ing. swicth and use the case screw to hang the fuse

 

[bgillen]

Re: 1974 omc alternater

p.s. great tip on the volt gauge

 

[RandyJ]

Re: 1974 omc alternater

I put one of the single wire alternators on my old 1970 chevy pick up... worked great!

 

[Howard Sterndrive]

Re: 1974 omc alternater

the new one you pictured is a 1-wire Delco. It is internally regulated so you can throw your external regulator overboard.
That lug on the chassis of it is for an optional ground wire (a good idea to connect a good ground from there to the block - same 10ga or whatever your 60A breaker line is - do not fuse it)
Hook your 60 breaker wire to the insulated lug, and you're done.
You'll need a voltmeter if you want to monitor charging. Some fishfinders show voltage.
I like these ones that just sit in the cigar lighter.

 

[bgillen]

Re: 1974 omc alternater

Thank you much Howard! U the best I'll be back on the water first am! Love ya dude. (I didn't even know about the cig. volt meter.)