A friend of mine recommended I get a GM alternator with a one wire application. He said it eliminates the voltage regulator and one wire goes to the battery, that's it? Anyone do this conversion, and do I need different mounting brackets?

 

You will need to fab some mounts or modify the existing brackets. I currently have GM one wire alternators on my 390, 1949 Farmall A, 1956 Minneapolis Moline 445, 1971 MGBGT. All required some bracket mods and all are working great.

 

I also did the conversion,after getting info,with photos from the archives.THEN,I did my due dilligence and did some further investigation.While my system is working great,there are some real disadvantages to the one wire versus the 3 or 4(not sure what the alternative is) wire alternator.I do know that my idiot light for the charging system doesn't function with the 1 wire set-up,but the real disadvantages are more significant than just this.Had I to do it over again,I'd use the three wire.At least I tried to keep mine sort of period correct by using a black powder coated one from Summit Racing.Do a search and you should be able to find the link that will dicusses the advantages/disadvantages of the two systems.Steve

 

It's working great, right? You don't need the idiot light, that's what one of the other wires was for. Most of these old trucks have ammeters which are superior to the idiot light anyway. You can convert a 1-wire to a 3-wire if you want to complicate your life!

I used to be under the same misconception that is still floating around, that the 3-wire's were superior because they sensed "real" system charging needs, and because the 1-wire required rev'ing to 1500 RPM +/- to start charging. The truth is, those were true statements for an early factory model of the 1-wire. What are being sold now as 1-wires have an improved internal module that eliminates those concerns. The original factory 1-wires were created for stationary engines that don't have accessories (like headlights or heater fans) and they weren't able to deal with accessory loads very well. They depended on residual magnetism in the stator or rotor to "kick off" which sometimes took a bit of RPM. All that is gone with the new models, a case of the aftermarket responding to our needs.

I have one on my flatty and it transformed it into a truck I can depend on. It's no secret around here, I HATE generators!!

 

Hi Ed, I,ve got a G.M. 1 wire alternator on my truck, and the wiring was easy. I used zoops brackets. They are costly but do the job nicely. I,m pretty sure they have one for your application.

 

Madelectrical www.madelectrical.com is the site that has some in-depth discussion on the matter.Check out their electrical tech section.It's comprehensive ,and easy to read and understand,which is necessary for me.Decide for yourself.Steve

 

I use the one wire on all my classics. Never had any problem. Thay work great

 

OK, I read that site's explanation. Entirely correct, but here is the crux of their argument for the 3-wire:

"In many factory-original wiring systems, the entire electrical system will draw power from the main junction, and the battery will charge from the main junction too. If we have a 2.5 volt drop in the long length of wire between the alternator and the “main junction,” and start out at the alternator with 14.2, then we only have 11.7 volts at the main junction. Expect dim lights, weak ignition, and slow electric radiator fans with this system being powered by a “ONE-WIRE” alternator.<?XML:NAMESPACE PREFIX = O /><O:P style="MARGIN: 0px"> "</O:P>
<O:P style="MARGIN: 0px"></O:P>
<O:P style="MARGIN: 0px">Can you think of any of our trucks having a long enough wire to drop 2.5v between the alternator and the "main junction"? Even at 100 amps, using V = I x R, a 2.5v drop equates to a wire resistance of .025 ohms. #10 wire has a resistance of 1 ohm per 1000' or .001 ohm/ft. So to get that .025 ohm drop, the wire from the alternator to the junction would have to be 25 ft long. The junction would have to be on the back bumper! If you used a #8 (which would be the correct size), it would have to be about 40 ft long. Most of our trucks don't ever need anywhere near 100 amps, anyway, I think headlights are still the major load and they are less than 20 amps (incl. running lights). If you have EFI, A/C, power windows, and a killer stereo, this could be a concern.</O:P>
<O:P style="MARGIN: 0px"></O:P>
<O:P style="MARGIN: 0px">Everything they say is true, it just isn't something any of us are likely to have a problem with. I don't know anyone with a 1-wire who has any complaints. BUT there is absolutely nothing wrong with a 3-wire, either. </O:P>

 

I'm using the three wire only because I had a couple of them laying around in my garage and I was too cheap to buy a new 1-wire. The extra two wires are nothing to hook up. Since I'm running a voltmeter in my dash, I wanted something else to catch my eye if the alternator quit working so I ran one of the three wires to a light on my dash. Now I have both a voltmeter and an idiot light. I like having both. The third wire is only a ground so the 3-wire is really nothing to wire up. Another afvantage of the 3-wire is that you can get them at any parts house. There may be a few parts houses carring the 1-wire now but most have to be mail ordered from places specializing in rod parts.

 

While this is not a concern with our trucks, I have run across a few earlier 1 wire alternators that would actually pull the battery down if run without energizing. This was on stationary pump engines that were started and then the pump put in gear at low speed and never revved up enough to energize the alternator. Had one old farmer that gave me a considerable cussing about the cheap alternator I sold him because it would run his battery down. Had to go back to a 3 wire with an oil pressure switch to energize it.

Jeff

 

Ed,
I just did the same when I rewired my 55. Went with a GM style with the voltage reg piggy backed to help clean up the inner fenders. Fortunately was able to match the style so the bracket did not have to change. The alt was not cheap though.

 

I have a gm one wire on the 302 Ford motor in my 46 coupe, been on there a long time with no problems. Seems like I had to make a spacer between block and alternator, and maybe enlarge the hole in the alt. Been a long time. Nothing hard. I have a Power Master one wire Ford alternator on my effie motor.

 

Ed, why do you want a GM unit? I installed a chrome Ford unit on my 289. I bought it at American Pasttimes ($105.00 in 2004). It is a one wire and uses the stock brackets. I am now seeing these one-wire units at the swap meets in colors like red, blue and yellow. I bet you could pick up a killer deal at the next Pomona Swap. Good luck, Jag

 

Jag, I didn't know Ford had the one wire that would work. Since I'm not into alternators, I'm going by my friends recommendations. He builds streetrods and recently did the one wire GM on a 289 on a 64 Ranchero he did and installs these alternators on most of the hotrods he builds. He made all new brackets out of aluminum to make it work. I'd leave mine alone (3 wire old style ford), but I'm getting tired of looking at the voltage regulator mounted on the firewall and the alternator wires harness going along the frame to the alternator. One wire across the intake manifold would be nice. I've seen the alternators on ebay going for about $80 in chrome. There is different Amp ratings on these alternators. Do I need one with 100 or more amps? I'm not running A/C or anything at this time with big draws on electical, but am planning to install A/C in the future. Anyone got a pic they can post of their GM alternator (or Ford) one wire install? Thanks guys.

 

I have a pic in my gallery. It shows two wires. one is for the gauge. I'll try to copy a link here:

https://www.ford-trucks.com/user_gal...=80433&width=2