Alternator upgrade?

[1972CST]

Im looking to change over to a one wire alt. on my blazer. What would be the best application to purchase one for? My water pump and pulleys are from a mid-70,s truck. Im guessing the higher the amp rating the better.

[trz1000]

This is what I used and so far am very happy with it.

http://www.summitracing.com/parts/SUM-810350/

I've also used Powermaster 1-wire's and am considering an MSD unit for another ride (it's real spendy but looks really cool). I went with the Summit brand this time as I've had some trouble with a couple of Powermasters in the past. I actually like it better than the Powermaster, more stable voltage at low RPM's stopped at a red light with the stereo blasting, wipers going, heat on, and bright lights. I don't get any dimming with the Summit but my 1/2 ton with a Powermaster will have noticeably dimmer headlights. Dimming lights with the stock alternator was a pretty big problem which was my initial reason for going for more amps.

I have a pretty hard thumping stereo and planning halogen headlights real soon so I went with 140amp. You could easily get away with fewer amps if you're not going to have much more electrical draw than stock. Stock is 60 or 80 amp I believe.

There are lots of strong opinions concerning 1-wire vs. 3-wire. Lots of people will cite several resources why 3-wire is better but, for me anyway, the benefits of having a dash dummy light don't register. I have a volt meter and keep an eye on my gauges.

Another argument I hear is that a 1-wire won't turn on until RPM's hit a certain number (1000, 1200, something like that). Well, when my Jimmy first fires, it briefly gets close to 1500 (as do/did every carburated vehicle I do/have own(ed)) so no problem there. If your ride doesn't just blip the throttle and bingo, alternator on. Contrary to somewhat common belief, the alternator does NOT turn off when the motor is running below the start-up RPM's. I think the motor has to stop for the alternator to turn off but I don't have anything to substantiate that. I can say that while messing with the carb one day I adjusted the idle to just under 400RPMs, just to try it I suppose, but anyway the alternator was still charging. Needless to say, I have a low opinion of that argument as well.

I've had 1-wires on a few of my rides and will probably never go back to a 3-wire.

[Monte Carlo Man]

Not to be combative, but the reason for the 3 wire set up is that one of the wires is used to burn the idiot light when the alternator is not charging.

The old style charging system had a external voltage regulator - which was a much better set up then the newer style internal voltage regulated alternator.
The problem with the older style was finding a high output alternator.
There was no halogen head lights, loud stereo's or computers to drive 40 years ago and so a 65 amp alternator was a high output alternator back then.

About the best high output external alternator was probably one for a ambulance because it was a more traditional vehicle which required lot's of power to run all the lights, radio and siren.

Any newer style alternator - 1974 - 1984 can be converted to a one wire set up in about 15 minutes with a minimum of tools and experience. As long as you can push the brushes back into the holder and pull the wire out of the back of the alternator to release the brushes once you have it together - there is nothing to taking the trio out and putting the new voltage regulator on and putting it back together. You don't need some over priced alternator from Summit. I think I had $20 into the last one I had done.

[Tom Vogel]

First of and probably MOST important.... I hold the high distinction of being the absolute last person on this entire board that you would be advised to ask for electrical advice!


With that disclaimer out of the way... I purchased my wiring kit from American Autowire(thru Wes at Classic Heartbeat).. Their advice on single wire alternators was... Dont. They say you will have far less trouble with the external voltage regulator setup. They really are the guru's. Not my advice but theirs FWIW. That is the entire scope of my expertise (ha,ha) on the subject.

[1972CST]

Wow, that got a few unexpected replies but very good info. It seems the more common 3-wire internally regulated alt. might be the way I go. I am shocked to hear that the external regulator is more reliable... I thought maybe thats why GM went away from that style. Thanks again guys.

[red71cheyenne]

Ya, I thought the one wire was the way to go too. Turned out to be a bad idea. Had to rev the engine to get it to charge and once the engine slows back down, no juice. I went with a CS144 like my 95 Suburban has on it, like 94 amps. Just had to change the pulley out and add a resistor to the sensing line. This still did away with the external regulator, but the alternator itself monitors the voltage and puts out as soon as you start no matter the engine rpm.

[FRENCHBLUE72]

I ran a one wire on my 4wd toyota with all the normal off road crap on it and the one wire sucked i.m.o. and yes when the truck was at idle it did not seem to charge very well went back to the 3 wire internally regulated set-up and it works soooo much better at least for me..

[Monte Carlo Man]

Just think about it like this.
The external regulated voltage regulator has two sets of points in it.
The one set - adjusts the low voltage, the second set adjusts the high voltage.

If you wish to use a 16 volt battery to start your engine quicker, all you have to do is set the voltage to 17 volts and the battery will do the rest.

With a internal regulated alternator, if the trio or the regulator burns up - you have no voltage or a very high - unregulated voltage. You ever see a 12 volt battery with 18 volts put in it. It looks like a high school teen age girl, 9 months after a all night beer party.

My 67 Panel truck just turned 43 years old the other day and it still has the original 37 amp alternator and external voltage regulator on it, and I believe that it has almost 375,000 miles on it.