One Wire Alternator Conversion

[Chevy 350 Fan]

Hey guys I'm a senior in high school, I have a 72 GMC C20. I installed an American Auto wire kit on this truck. The one part I have yet to figure out is the alternator. I think I would rather run an internally regulated because I had nothing but problems with the externally regulated. So I was going to go to auto zone and get an alternator for like an 80's truck. Now my question is how do I hook it up? I no longer have the wires for the regulator set up (truck caught on fire few months ago and I gutted all that ****) So all I have is the brown wire coming out of the firewall connector. According to my diagram and what I remember there are 4 wires for the regulator: blue white, red and brown. From what I've read you connect white to red and brown to blue. So since I'm starting from scratch here in my mind I think I ought to be able to run the brown wire straight to the alternator and splice the red power wire coming off the back and have it go to the other connector on the side of the alternator and then the other lead go to the battery. does that sound acceptable to you guys? Here's a picture of a wiring diagram I found on how to do it. FYI I do have the factory diagram as well and wire colors match up. let me know what you think
Thanks!

[Chevy 350 Fan]

Here is that picture

[Chevy 350 Fan]

Here's another question I got. The standard alternator is 63 amp. Do you think that that would be enough? I'm running a built 350 corvette motor makes 500 HP. I'm running MSD ignition (6AL with a blaster coil) Holley red electric fuel pump (says it only draws 2 amps) and electric cooling fans (25 amps). I might get an electric water pump also at some point. The electric water pump I was considering draws 20 amps it says. In addition to those mods there is still all the stock equipment: lights, wipers etc. so do you think 63 amp is going to be enough or should I reconsider my approach here?

[RodnRudy]

I'd get a 100 AMP alt. minimum. Also the red power wire from the alt. to the battery should be at least 10 ga.

[Already Gone]

I'd check out this thread and do little thinking before you go to one wire alternator. There are some concerns going to one wire alternator on our trucks.

http://67-72chevytrucks.com/vboard/s...23#post7387223


http://www.madelectrical.com/electri...hreewire.shtml

[LSGarage]

Read Mad Electrical, learn it, know it. Do not go the one wire route, just my 2 cents worth

[Chevy 350 Fan]

My ignorance is going to show here so please bear with me: I thought an internally regulated alternator was a one wire alternator I've never heard of 3 wire. Would you mind explaining the difference? I did some research, looked into those links and from what I understand a one wire voltage is sensed at the alternator and 3 wire it is sensed at another location???? (I would assume external v regulator) but that couldn't be the case because then it wouldn't be internally regulated. Maybe posting a wiring diagram would help. I'm sorry my knowledge is a little lacking on this subject haha, I just don't want to fry anything that I worked really hard to buy and install.Thanks for the replies guys!

[ray_mcavoy]

Originally Posted by Chevy 350 Fan

My ignorance is going to show here so please bear with me: I thought an internally regulated alternator was a one wire alternator I've never heard of 3 wire. Would you mind explaining the difference? I did some research, looked into those links and from what I understand a one wire voltage is sensed at the alternator and 3 wire it is sensed at another location???? (I would assume external v regulator) but that couldn't be the case because then it wouldn't be internally regulated.

Externally vs. internally regulated just describes the physical location of the voltage regulator ... not where the regulator is sensing the voltage.

A "3 wire" alternator is basically just a stock internally regulated alternator. However, you probably haven't heard it called that because the term "3 wire" isn't all that common.

As the name implies, a "1 wire" alternator only has 1 wire to hook up to the vehicle's electrical system. But because of that, it can't compensate for voltage drop in the charging system wiring due to it only sensing the voltage at it's own output terminal. And a 1 wire alternator also lacks the ability to operate a warning light.

[gmachinz]

I've provided a lot of harnesses for various swaps like this. I'd suggest getting a CS alternator for the amount of accessories you're planning to run. Go to a parts store and have them pull down one for a 1988 Olds Firenza 2.0FI. It has a serpentine pulley that can easily be swapped for your v-belt pulley. Then, modify the wiring for a CS alternator and you're all set-this alternator is a small case, 105A alternator and features 12 and 6 clocking.

I'm a bit confused-did your under hood wiring catch fire before or after your AAW install? Do you have a good harness to use still or do you need to go with a CS specific alternator add-on harness section?

[vince1]

From what I understand if you order a CS130 for an 89 Pontiac Safari it comes with a V pulley. An advantage of the CS series is that they charge so much better at low RPM. You would need the PL(I/F)S connector with it. Your brown wire would go to L for lamp and the S for sense could go where you want to sense the voltage, or if you want more simplicity, just put it to the output post.

if you want to go cheap like me, get them from the auto wreckers. I quite often find them brand new looking with a recent overhaul tag on them. Serpentine pulleys can be swapped out for V pulleys. There are lots of different mounting options so look for one of the smaller ones with the lugs 180 degrees apart and 6.6" across. I always keep a spare and if they need one offer them at cost to local club members.

[Chevy 350 Fan]

Originally Posted by gmachinz

I'm a bit confused-did your under hood wiring catch fire before or after your AAW install? Do you have a good harness to use still or do you need to go with a CS specific alternator add-on harness section?

No the whole truck caught on fire when I was driving her to school in the spring hahaha. I spent my summer redoing her. she's just about finished now. just needs a few things ie: Alternator lol

[Chevy 350 Fan]

Thanks for all the replies and suggestions guys! ill take them all into consideration.
Colton

[VetteVet]

Originally Posted by Chevy 350 Fan

Thanks for all the replies and suggestions guys! ill take them all into consideration.
Colton

This is how simplistic the conversion is.
You know which wire is the brown exciter wire for the alternator so just connect it as shown below.

For the late eighties SI 12.






And for the CS 130s and up



You might also check out the thread link in post 5 where we explain how to wire the two. If you intend to retain the battery gauge function in your gauge dash then you will have to wire the gauge as shown.