The Stovebolt Site Forums The Shop Area The Electrical Bay alternator for 51 GMC 228 engine

Well everyone, I have been soing alot of reading about this subject in the forum and at MAD. I beleive for my application a 1-wire alternator would be sufficient. I have a 51 GMC 1/2 T longbed with a 228 cubic inch 6 cylinder. Can anyone tell me what specific alternator I should ask for at my local Auto parts store??

I plan on installing a junction box at firewall with a dis-connect function to hook up to. The junction box will be some 6-5 feet from alternator and some 3 feet from battery. what size wire should i use from alternator to junction box?? Will I have too much voltage drop at this length??

Will I need to fabricate bracket or does anyone have ideas on how to fasten to block??

Any help appreciated, getting close to taking on road!!!

If you do any driving at night the one wire alt. won't be sufficient.

You should use 10 ga wire minimum to the junction block and should run a voltage sensing wire from the 3 wire alt. to it.

There will be a considerable voltage drop in the 5-6 ft. of wire to the block then an even more considerable voltage drop when you turn on the headlights. The one wire alt is sensing from itself and it doesn't notice these drops so it doesn't compensate for them. With a sense wire at the juction block it will notice it and compensate for it.

I have the same truck as you. Just curious why you want to go to an alternator. If your going to put in a high powered stero system, just go with a 12volt system and good 12 volt generator.
Cecil..........

Cecil, depending on what all he's running with that alternator, a generator might not have enough output.

I second the motion about avoiding the 1-wire alternators. You have a truck, not a boat...use a three-wire.

Forget that 1-wire idea -- them are for tractors!

Put a Delta 12si in there, man -- it just doesn't get any better than that!

Is there some special reason you wouldn't just run the alternator output to the batt post on the starter. Isn't this how the original system was wired. I have seen 1 wire alternators advertised but never investigated them. From Cletis' comments, I would assume there might be a issue with the ability of them to sense a small increase in current demand and to switch on. Is this the concern?

Stuart.

I don't know about how they were originally setup, except that they were set up with generators, not alternators, and that's a different ball of wax.

The 1-wire alt's are used on tractors ... a much simpler setup and not of much use for our trucks (unless maybe if it's a show truck and never gets driven).

The absolute best way to setup your engine area and your truck's electrical distribution ... as far as I'm concerned ... is with a power station under the hood (terminal blocks) -- like THIS - Click Here

What I love about the Delco 12si (aside from mine delivering 100 amps) is that, with a Delco regulator built in, it monitors everything very concisely -- even to the point of sending lower voltage when the battery gets hot (like in summertime) ... saving the life of the battery and everything else in the truck, including wires, etc.

Alan,

Internal regulators have been quite common for many years. I don't know about the tractor connection, but the single wire alternators seem to be the rage now for automotive use...next to a 50,000 watt amp in your trunk, a chrome,
single wire bazillion amp alternator is the real ticket. With two teenage boys in the house, you can't walk far without running into a Hot Rod or Off Road Jeep magazine. As usual, I LOVE your site, it's my place to go for solid information and great pictures.

Stuart.

Thanks, Stuart

I wasn't bragging about an internal regulator ... but about the Delco alternator that has the Delco internal regulator (any other internal regulator doesn't perform as I mentioned!).

This will tell you the differences between one wire and three wire and how to hook each up.

http://www.madelectrical.com/electricaltech/onewire-threewire.shtml

Inky05,

Looks like that's the way to go! Thanks for the lead Alan.


Stuart.

I'm running a GM 10si alternator in one-wire configuration on my 261 and it is working just fine. It bolted right up by just elongating the holes in the bottom generator bracket and flipping over the top bracket. I plan to switch it to 3-wire eventually, but it works just fine as-is. It starts charging as soon as you bump the engine over 1000 rpm, and it still charges at 600 rpm with the headlights on. I just ran a new #10 wire up to the post on the ammeter that connects to the voltage regulator and disconnected the old voltage regulator. The 63 amp 10si works just fine for my truck. Any of the GM si series alternators are good and dirt cheap. Mine was $30 at autozone.

I have also run one on a wide-belt 216 by just swapping the old generator pulley over to the alternator. The shaft diameter was exactly the same.

What we really need is for Fritz999 to tell us what he's going to add or do to the truck. If your here, please let us know your additions so that we can give you a better answer based on your power needs. Cecil.........

:confused: I guess I'm missing something here because I know a number of streetrodders who, of course, run 350's in their cars and everyone of them uses a one wire alternator.

In most cases, these guys are running A/C's and pumped up stero systems, some even have electric windows, etc.

I always thought a one wire was the way to go. :confused:

Joe

well guys what a responce. i have decided to go with a 3-wire alternator. i purchased one today and have it mounted in truck by 830 tonight. took pulley and fan off old generator and put on new alternator. took bottom bracket off and drilled new holes and turned it end for end and remounted it. took top bracket and reversed it and it is mounted.

Street rodders do a lot of things that are looks before function. If you aren't going to use your truck except to drive to a show every month or so the one wire will probably be sufficient. Keep the battery on trickle charge between shows.

tomorrow i am going to get a junction block with a disconnect feature. going to run wires to and from that. will mount this somewhere above the starter thru the firewall so i can turn power off from inside. liked the idea of a remote sensing wire that tells the alternator to juice up when needed from the junction block.

Cletis -

You are right, and not to argue the point, but a bunch of the Model "A" Club guys are running one wires on their vehicles, too. In fact, I bought my original alternator, which was a GM, from a Model "A" guy. Those Model "A" guys will put GM parts on their cars without batting an eye. They have no shame.
I saw a Model "A" last Saturday with a T-5 in it - an S-10 T-5!!! Tisk, tisk!

Joe

I guess I have been very lucky with my 1 wire alt on my 1958 Chevy with 261 six. Over a six year period of solid driving. Average about 12,000 miles a year I have never had a problem until the pinion bearing went out. The battery was 5 years old when I had to park the truck. Went all over the state of Texas in that old truck. Soon I'll replace the bad bearings, and ring and pinion gears and start driving it again.

Roy Rodgers,

I have heard of other folks burning up the pinion bearing in their alternators.


Stuart.

Hey, Joe

... and anyone else who wants to fully understand why we shouldn't use a 1-wire, Read This

Auto marc,

I can tell you from experience that when that pinion bearing in the alternator fails its a memorable experience. Makes you wonder how they got something like that in those alternators to start with.

I have spent a good amount of time in the electrical field, and I disagree with some of the things that MAD and others are saying. I'm not disputing their facts (like the warning light, etc), I'm just disputing the conclusions that they draw.

A lot of the reason people are so dead set against 1-wire alternators is that the initial voltage regulators had some problems. There were quite a few of the early ones that failed, causing all kinds of problems. The early ones also had a problem with the self-exciting loop, which lead to a lot of dead batteries and annoyed hot rodders. After including the 1000 rpm sensor, almost all of the problems went away. The new 1000 rpm switch turned on the alternator and kept it on all the time that the engine was running - exactly like the 3 wire. The early ones didn't do this - they would shut down at idle, which caused all the problems. This is why it was initially used in boats and tractors - vehicles that usually didn't operate at idle.

Todays 1-wire alternator are just as reliable as the 3-wire. I've personally had one in my truck for 8 years now, without a single problem. I used it to replace an externally regulated alternator that kept draining my battery (fused contact in the regulator). The 80 amp 1 wire alternator allowed me to eak out life of a dying battery for more than a year.

The interesting thing is that the 1-wire is really exactly the same as a 3-wire. The 1 wire regulator is a 3 wire with basically a rpm switch and a diode added - nothing else. The violent protestations of the people who are pro 1-wire or pro 3-wire is all over absolutely nothing - because it is the same part, just wired slightly different.

The 1-wire is a boon to a majority of guys that have absolutely no desire to understand their wiring harness. I have fixed a countless number of trucks simply because the owner hooked up the wire that turns on the alternator field wrong. Most of them tie it directly to the battery. While that will work, it will quickly drain the battery while the truck is off. Most of them would rather pay $100 or so for a 1-wire than take the time to fix their 3-wire properly. The only thing they lose is the warning light - which most people don't care about anyway.

The MAD article says that 3 wire regulators are better, for 2 reasons.

1. Loss of the alternator light. This one is kind of dumb, because if the alternator isn't charging, you know it almost immediately. Lights dim, stereos stop, starter turns over slow, etc.

2. The alternator isn't turned on with the ignition switch. Once the motor hits 1000 rpm, the functional electrical connection on the alternator is exactly the same as on the 3 wire. No electrical difference.

I don't want flame anybody, but it is obvious to me that this article is based on opinion, not founded on design theory.

Cool.

Thanks for the clarification, Vaughn ... I imagine you put some minds at ease and what you say sounds logical to me.

I'm still a firm believer in the Delco 12si, with the Delco internal regulator ... but that's only because of positive personal experience and a nit-picky personality.

This topic comes up about once a month. For people who have already chosen a style of alternator (and thought their choices over carefully), it's a lot like discussing which religion is better. If our alternator (religion) has worked for us, we seem to have a need to argue that our's is the best.

For people who have never converted to an alternator, they hear all sorts of opinions and this must be confusing.

On a completely different matter, that is a little off topic: fritzer999, has you truck already been converted from 6 volt positive ground to 12v negative ground?

Tim

If you lose your belt your engine will heat up almost immediately. It could be toast before your lights dim, stereos stop, starter turns over slow, etc. If you have a light you know when you throw a belt.

Vaughn -

This a great example of the usefulness, beauty and power of The Stovebolt Page to me. Here is a good, clear, understandable explanation of something that almost everyone has wondered about - even the guys running generators, because they have considered alternators, but many times don't understand the alternator and it's functions. I appreciate the time you took to write that and thank you!

I have one question. Explain better, if you would please, where you should hook the one wire to. You say "guys will hook it to the battery and it will drain the battery when the truck is off". Where should it be hooked? :confused:

Thank you again!!
Joe

JOE,

I think Vaughn was refering to the 3 wire alternator discharging and draining the battery when wired improperly. On the 1 wire unit, the alternator output would attach in a conventional manner, to the starter, a solenoid or wherever you choose, although I'm not clear on why you would mount a block, or blocks to the firewall and put the wire there!

In a 3 wire system, the one with the plug in the back, the #1 (R) wire is switched to only be engergized when running...the #2 (F) is attached in the circuit, unswitched, to sense battery voltage. If a diode fails in the bridge rectifier, it allows the battery to drain through the #2 wire and discharge. . I am not sure if Vaughn suggested "switching" the #2 wire to save the battery in case of a bridge failure, but this isn't SOP anywhere I know of. If the bridge fails, it might drain your battery, but the bridge has still failed and the alternator needs to be repaired or replaced.

It is not complicated to hook the 3 wire alternators up properly. Which one you choose would be a personal choice based on your needs. Gee, I hope I got this right.

Stuart.

Stuart,

For what it is worth, I agree with you. One reason for using the one-wire alternator would be that there is no need for any extra wires (than are available in the original generator-equipped harness). I think that I simply had to disconnect the leads to my old regulator and attach the alternator to the heaviest generator-lead; and, at the old voltage regulator, take that disconnected lead and connect it to the ammeter lead (I think that is what I did). This sets up the charging circuit to the battery and you have a working ammeter (same ammeter works with 6v or 12v alternator).

When I change my wiring harness, it will be a 3-wire alternator harness from Chevy Duty. This will allow me to use a 1, 2, or 3-wire alternator when the 1-wire 12v alternator that I have (7 years old) wears out. When that happens, I will most likely go with a 3-wire unit (price will then be the deciding factor).

Tim

I think the warning light is a big issue - if something is going wrong, I want to know NOW - not when I start losing battery power. That way I have some control over how I handle the situation. I'm a paranoid - give me a warning light AND a voltmeter.

thanks guys. you have been great help.
my truck has already been converted to 12v negative ground. also talked to good machanic at john deere store yesterday. i may need to install diode in line since it wont turn off when key is turned off.

I put a diode in mine ... simple, easy ... and wow -- what a difference.

PS -- How do we run an idiot light for a 3-wire alt that lets us know if the belt takes a vacation unexpectedly??

Alan,

Why did you put a diode in yours? What was the purpose and how did it make a difference?


Stuart.

Hey, Stuart

When I decided to improve the wiring under my hood (a year after I did the EZ-Wire install on the truck), I did a number of things.

One was to place two terminal blocks on the firewall which delivers a full 14 volts to important stuff like my fusebox (on the interior side of the firewall), the alternator, my headlights and electric fan ... and also talks to the internal regulator (note the #2 wire in the drawing), so it is reading what's truly being fed to everything, right there at the source of voltage delivery. I also employed relays and fusible links:
[img]http://www.alanhorvath.com/54chevy/chevypics/wiring_2.jpg[/img]

Then, being a fan of MadElectrical.com , I ordered his Alternator Wiring Kit which included a diode ... I knew nothing about diodes, so I called him and asked about it.

The diode keeps electricity flowing in one direction only ... it's placed on the #1 wire of the alternator (see drawing above) and stops the electricity from flowing back to the ignition, which causes "engine run-on."

Before the diode was installed, when I would turn my ignition off I didn't really get "run-on" but I could tell the engine would hesitate about a second before actually stopping. After I installed the diode, I was really impressed at how the engine really stopped instantly at ignition turn-off!

NOTE: You can buy a 4-pack of diodes from Radio Shack for only $3 or $4: Part #1N4001. You'll notice that one end of the diode is marked with two stripes -- that end needs to be pointed towards the alternator.

Alan,

Your posts and SOOOO complete, informative and, non-judgmental...I like em! I read earlier posts about " run-on" and a incorrect type of ignition switch being the cause. I think 4onthefloor
shared some info on this topic. I don't know if you use a stomp starter or not, but did you have to change or modify your key switch in any way?


Stuart.

Thanks, Stuart.

No ... my ride is all street rodded. I've got a mid-70s Cadillac steering column (ignition), a 350sbc with headers and a mild cam, a 350TH trans, Mustang II IFS, mid-70s Chevy 12-bolt rear, etc.

Alan, the warning light goes where you have a diode. It serves the same purpose for instant shut down plus provides the warning.

Thanks, Cletis

Can you explain in more detail how to install the light? Where goes what? I need a dummy-sheet; A, B, C.

This scematic is the best I could find. It shows it but you have to hunt.

Follow the curcuit from the #1 terminal on the alternator and it will lead to the light then to the ign1 terminal.

It is my understanding if you have the light you don't need the diode. The resistance of the light serves the same purpose. Don't ask me how. I just know I have the light on my externally regulated alternator on my yard dog and have no problems.

Thanks.