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  • which alternator. 3 or 1 wire.

    Hi all, just about finished installing the 351w in my 58 and now up to the wiring.
    What's people's thoughts on alternators. 1 or 3 wire, which is easier to do and how's the simplest way to go about it.
    Thanks Chris.

  • #2
    Certainly, many Hot Rods were made possible by using the 1-wire alt. Having said that...

    I believe, if you understood the electric aspects of each, you would quickly choose the 3-wire alt. Exactly what are the three wires? One is the chassis ground, another goes to the battery +, and the third is magic. Just kidding. The third wire senses your key switch is turned on, which is something the one-wire cannot do.

    Ford cars have a GEN light that is connected to your OEM voltage regulator's ARM terminal (I think it's black and yellow). When converting to an alternator, use that wire for the third wire connection. When you turn your key on, your GEN light will light until your engine starts (just like it used to). If you throw a belt, the GEN light will shine (just like it used to).

    The most important facet is, when idling at low rpm, your 3-wire alt will still charge. A one-wire will not because it depends on engine rpms to prove the key is on. Not good in a parade or serious cruise.

    I understand GM one-wire alts use a very expensive internal regulator and if it ever needs to be replaced, this part is hard to find. - Dave
    My latest project:
    CLICK HERE to see my custom hydraulic roller 390 FE build.

    "We've got to pause and ask ourselves: How much clean air do we need?"
    --Lee Iacocca

    From: Royal Oak, Michigan

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    • #3
      Ok, sounds straight forward enough. Is the original external regulator used or will a new reg also be required.
      Thanks Chris.

      Comment


      • #4
        You can buy a modern internally-regulated, higher amp alt cheaper than the old non-regulated alternators. Why? Because every car for three decades has one. The old stuff is not in demand and bone yards crush modern alt's daily.

        Add the price of an old alt with the price of a regulator.
        BTW, consider the output because before internal regulators, cars did not have electric fans. <--an essential component for fuel savings.

        Why buy an alternator if it won't support an electric fan? I mean, if you're going to fabricate brackets, why do it more than once?
        My latest project:
        CLICK HERE to see my custom hydraulic roller 390 FE build.

        "We've got to pause and ask ourselves: How much clean air do we need?"
        --Lee Iacocca

        From: Royal Oak, Michigan

        Comment


        • #5
          which alternator. 3 or 1 wire.

          Chris, when my alternator was installed, we left the original voltage regulator in place. It was not going to be used, except to make the connection to it that allows the hook up to the Gen light. As Dave mentioned, leaving the Gen light in the loop will let you know if your alternator has thrown a belt or is having a problem. That is the only wiring that is used in the OEM VR, as I recall.

          Ray Clark - Squarebirds Administrator
          '59 Tbird "The Yellow Rose Of Texas" aka "Tweety Bird"
          "It's Hip To Be Square"
          Thunderbird Registry #33025 VTCI #11178

          Contact me via Private Message for my email address, or (Cell) 210-875-1411 (Home) 210-674-5781

          http://www.squarebirds.org/picture_gallery/TechnicalResourceLibrary/trl.htm

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          • #6
            Excellent guys, thanks. I had been looking at a 3 wire internally regulated one as it is. So basically the only wire that runs through the old reg is the thing yellow/black one and I guess the others are bypassed.
            Brackets aren't an issue with a windsor but I'd be putting at least a 100 amp in to run fans etc.
            So apart from a new alternator what else would need to be purchased.
            Would u guys have a simple to read and easy directions for the wiring conversion, if so it would be greatly appreciated.
            Thanks Chris.

            Comment


            • #7
              which alternator. 3 or 1 wire.

              Chris, I don't know if you have checked the Technical Resource Library or not regarding converting from a gen to an alternator. If not, here are a couple of links you might want to check out, directly out of the TRL.

              http://www.squarebirds.org/Electrica...sion/GenToAlt/

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

              Yes, you only need to use that yellow & black wire for the Gen light. The rest are bypassed. The information is in the first link, as I recall. I think the wiring info is there also. Gots to get some sleep! Good night and good luck with this.
              Last edited by YellowRose; December 8th, 2014, 04:23 AM. Reason: Put in the right link...

              Ray Clark - Squarebirds Administrator
              '59 Tbird "The Yellow Rose Of Texas" aka "Tweety Bird"
              "It's Hip To Be Square"
              Thunderbird Registry #33025 VTCI #11178

              Contact me via Private Message for my email address, or (Cell) 210-875-1411 (Home) 210-674-5781

              http://www.squarebirds.org/picture_gallery/TechnicalResourceLibrary/trl.htm

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              • #8
                Ok, so I've decided to go down the one wire alternator path which is 100a and 55a at idle so hopefully works ok. Now hopefully my wiring sounds correct. Large cable with 150a mega fuse in line from alt to positive battery. Dash wire, horn wire, headlight wire too battery side of fuse. Cut and tape gen warning wire. Sounds correct so far I think.
                Now the starter solenoid needs to be removed as I'm using a more modern one.
                Now I need a heavy cable from starter to +battery, I need an earth from same location on starter to somewhere like the bell housing hopefully correct so far.
                Now the red/blue wire on old starter solenoid I'm assuming this goes to the starter, but where does the original coil+ wire go now.

                Hopefully this all sounds correct, if there's something I've missed, let me know.
                Appreciated, Chris.

                Comment


                • #9
                  Originally posted by chris58 View Post
                  ...Cut and tape gen warning wire...
                  The GEN light does far more than you think. When your car was original, it showed the Key Switch was turned on, the engine was not running, the light bulb was ok AND it tickled the armature in your generator (which establishes proper polarity). You simply see it as a 'warning' light.

                  NONE of the car companies use a one-wire alternator in new cars and they never have (not even GM with the 10SI). I won't go into, 'why' because that is discussed all over the net.

                  ALL OEM cars come with an alternator that USE a 'sense' wire for proper regulation. If you now have an alternator, you could change the word 'GEN' to 'ALT' on the light. That wire IS a sense wire. It tells the alternator your Key Switch is turned on and it reports 'dashboard voltage' to the alt. It also lets you know the Key Switch is turned on, the engine is not running (or you threw a belt) and the bulb is good. You cut yours off, in favor of an inferior and more expensive system.

                  I hope you rethink the one-wire thing. A one-wire may stop charging at idle speed until you hit the gas again. It compares battery voltage to charging voltage. So when current stops going to the battery it shuts off internally, because that is the only way it can sense the key is off. I hope this makes sense to you. If you simply drive your car at regular speeds, the one-wire has no problem.
                  Last edited by simplyconnected; December 14th, 2014, 01:02 PM.
                  My latest project:
                  CLICK HERE to see my custom hydraulic roller 390 FE build.

                  "We've got to pause and ask ourselves: How much clean air do we need?"
                  --Lee Iacocca

                  From: Royal Oak, Michigan

                  Comment


                  • #10
                    Ok, I'll take your word on it then. I'll stick with the 3 wire then. After lots of reading it makes sense anyway.
                    I know there's diagrams for the wiring but they're all Chinese too me. Am I on the right path with the starter side of things.
                    With a 3 wire will all other wires still run off battery side of mega fuse etc.
                    Sorry about all the probably basic questions but wiring not my thing and I've got a lot to learn.
                    Greatly appreciated, Chris.

                    Comment


                    • #11
                      I have never understood the desirability of the one wire system and installed a Delco 3 wire with internal reg many years ago. It has been trouble free in my 57. One side benefit is the cleaning up of the mess of wires an removal of the regulator from the inner fender.

                      Comment


                      • #12
                        Originally posted by Joe Johnston View Post
                        I have never understood the desirability of the one wire system...
                        Here is exactly why, Joe:

                        Originally posted by chris58 View Post
                        ... there's diagrams for the wiring but they're all Chinese too me...
                        ...wiring not my thing and I've got a lot to learn...
                        You are not alone, Chris. People hear, "one wire" and they immediately think this is an easy hookup and easy to troubleshoot.

                        It's NOT one wire, it's really two because every electrical path needs two wires to complete a circuit.

                        The three-wire simply has one more small wire to sense the key switch position. The third wire is already there for you to use. GM and Ford alternators operate the exact same way and they are both equally as dependable. That opens many options for you to use whatever is most convenient (or inexpensive).

                        If you need to understand this diagram, ask questions. I am sure others would love to understand more as well:

                        I hope this helps.

                        If I man draw your attention... You do NOT have to use your GEN light (but I would since it's there). Look at the wires coming out of the alt, they all go to Battery +, eventually. - Dave
                        My latest project:
                        CLICK HERE to see my custom hydraulic roller 390 FE build.

                        "We've got to pause and ask ourselves: How much clean air do we need?"
                        --Lee Iacocca

                        From: Royal Oak, Michigan

                        Comment


                        • #13
                          Ok slowly starting to make sense. Now obviously I won't be using that style starter solenoid so which wires need to go to my new starter. I may aswell get this sorted whilst I wait for new alternator which I've just ordered.
                          Thanks Chris.

                          Comment


                          • #14
                            Alright, this is easy. Let's start with your small push-on "S" wire. If you are using a modern 351W starter, it has a small flat "blade" terminal to energize the starter motor (from your Key Switch). Simply make a #16awg extension with a crimp-on flat blade female connector at the starter end. You can splice your new extension to the old wire or put a #10 bolt and nut on the end and push your old wire onto it. Tape it after connecting.

                            Every fuse needs a holder so that no mechanical vibrations or pressures upset or break the fuse. We mostly use fuse blocks for small fuses and very large single holders for mega-fuses that look like this:
                            <--click on the picture for the link.
                            Another device we use is a 'surface mounted junction block' that looks like this:

                            These are quality electrical parts with copper lugs and nuts. The old studs were 5/16" (8mm) so the new ones should be the same size.
                            Now, let's put it together...
                            Remove your existing Starter Solenoid (relay) and mount BOTH the fuse holder and junction block in the vacant space on your fender apron. Connect a short 'jumper' from the fuse holder to the junction block. Connect both large cables that came from your old Starter Solenoid to the same junction block stud. Done.

                            Now, you have provisions for the new #6awg wire to your new alternator from the fuse holder. The 'sense' wire from your alt. can connect to the new junction block stud or the battery side of your mega-fuse holder. All your old battery and starter cables can be reused.

                            Questions?
                            My latest project:
                            CLICK HERE to see my custom hydraulic roller 390 FE build.

                            "We've got to pause and ask ourselves: How much clean air do we need?"
                            --Lee Iacocca

                            From: Royal Oak, Michigan

                            Comment


                            • #15
                              Excellent. So the 'S' wire is the red/blue wire correct which comes off front of old solenoid.
                              The last wire on old solenoid is the + coil wire, where does this now go.
                              Thanks.
                              Last edited by chris58; December 14th, 2014, 08:14 PM.

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