7dSHARK

1970...Have a stock alternator now. Found one online that is 120 amp. They say you can hook it up in stock fashion or convert to one wire. The only advantage I am aware of with the one wire connection is a cleaner look. The company sais it is one wire straight to the battery. Does that mean you lose the use of your amp gauge. Asking people to weigh in on the subject. Wiring diagram would be great. Before and after pictures would be even better.Also, if I stay with conventional configuration what wires do I have to upgrade? Thanks in advance..Matt

TimAT

The one wire even at 120 amps, does not start charging until it sees enough RPM to excite the stator. THe GM 3 wire does the same theing, only it uses the small brown wire to excite and it starts the alternator working at idle. The PO had installed a one wire on Ol' Red, I swapped it back to a 3 wire.

oldalaskaman

TimAt says it best, if you have an external voltage regulator, you will need an adapter plug to make it work, if you have an internal regulator, just plug it in and run a larger charge wire, I didnt remove the original wire but just added an 8 gauge parallel to it. . it will work better as a three wire. mine puts out 13.78 at idle. If its the same one I have that lifetime warranty is a good thing. the chrome doesnt look bad either. cause you cant get it in satin
this one?
http://www.ebay.com/itm/GM-CHROME-12...item564c109f17

REELAV8R

Stay with a three wire alternator. The one wire alternator was developed for systems that do not have a voltage regulator as an economical solution. Your car's voltage regulator will work better.
I bought the exact one oldalaskaman reccomended in the three wire version and it works well.

7dSHARK

I think I found this alternator from reading your post. Looked at my wiring again. I have one ground wire, one positive wire and a plug in with a red and a white wire. I recently replaced the plastic plug in because the plastic was broken. I can't remember the original colors of the wires. I was suprised that one of the wires was solid and couldn't be soldered. Is that unusual?
Where do the wires from the plug in go (when they exit the alternator)and what do they do? How do I know if I have an internal or external regulator? Also I don't have the exciter wire mentioned and don't know if that is significant. Thanks

oldalaskaman

I believe your is external, here's a good write up


http://www.wallaceracing.com/alt-conversion.html

TimAT

Easy to tell-- if the connector on your alternator has two terminals like this " l l " it's an external regulator. IF they are in line " -- " it's internal. Sorry-- not to scale. The terminals are about 1/4" wide.

The two wires are in the harness- the large one (red) basically is hot all the time, and the smaller one (brown) (factory color) is hot (12v+) when the key is "ON" The other two, one large red to the output stud on the alternator, and a black wire to the alternator case ground.
GM swapped over to the internal regulator in the 68 model year IIRC.

Ironcross

68 is the last external regulated alternator.....69`s are internal....my opinion, leave it a 3 wire and enjoy....One wires are good for 'hot rods'

74 LS4-454

Not to highjack the thread, but can you explain this to me, as my alternator doesn't seem to come to life until after I reach a certain rpm.

"The one wire even at 120 amps, does not start charging until it sees enough RPM to excite the stator. THe GM 3 wire does the same theing, only it uses the small brown wire to excite and it starts the alternator working at idle."

On the 82 I have a 3 wire and leaving early in the morning, I ease out of the neighborhood as not to wake up anyone, as soon as I get on the road and bring the r's up the headlights get brighter. So is that when the alternator starts charging from the stator getting excited? Is this normal for a 3 wire setup? thanks...................Tom

73ss

On the 82 I have a 3 wire and leaving early in the morning, I ease out of the neighborhood as not to wake up anyone, as soon as I get on the road and bring the r's up the headlights get brighter. So is that when the alternator starts charging from the stator getting excited? Is this normal for a 3 wire setup? thanks...................Tom[/QUOTE]

Do the lights dim when the r's drop back to idle? Aftermarket large diameter pulley will do this.

74 LS4-454

Do the lights dim when the r's drop back to idle? Aftermarket large diameter pulley will do this.[/QUOTE]

No they don't, once they get brighter, they stay that way. since my dash is still out of the car, and no gauges, I use my interior dome light as a "gauge" also. when that gets real bright, it stays that way, just like the headlights. have stock pullies.....
someone had mentioned to me that the alternator may have a "soft start", now that I think about it, that may be referring to the stator being excited by a certain rpm range.

73ss

No gauges? I believe the brown excite wire is wired to the gauges. the brown wire needs to "see" 12 volts downstream, away from the battery, to excite the alternator. Could be the problem??

74 LS4-454

The dash and gauges are going back in soon.....thanks for the info...

mrvette

No they don't, once they get brighter, they stay that way. since my dash is still out of the car, and no gauges, I use my interior dome light as a "gauge" also. when that gets real bright, it stays that way, just like the headlights. have stock pullies.....
someone had mentioned to me that the alternator may have a "soft start", now that I think about it, that may be referring to the stator being excited by a certain rpm range.[/QUOTE]

I forget wether your later sharks have a 'idiot' light or not, I believe they do have a volt meter though, IF you have a idiot light, that will be the cause, as it's not in the circuit....

7dSHARK

O.K. You guys have me sold on staying with three wire. Next question.......A friend gave me an aluminum alternator in great condition but with stock amps. I need more amps for my accessories. Can I or an alternator shop increase the amps. If so, what is involved?

oldalaskaman

they can or you can , but by the time you've spent the money and time, you wont save any thing

7dSHARK

Thanks to everyone for their help. I have direction now. New alternator it is. Matt