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Alternator 1G vs 3G |
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72TorinoRoth 
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Joined: 30-April-2021 Location: Oak Harbor, WA Status: Offline Points: 22 |
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 Topic: Alternator 1G vs 3GPosted: 15-June-2021 at 10:18AM |
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I’ve been reading the post Just a Small Fire where it was suggested to upgrade from the 1G alternator to the 3G alternator. I was looking around at Summit Racing and they show many one wire alternators with higher amp outputs and internal regulators. I understand basic electrical, but not enough yet to make an educated choice on which way to go. Please help.
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aquartlow
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Joined: 19-December-2011 Location: Summerfield, Fl Status: Offline Points: 2271 |
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Posted: 15-June-2021 at 11:36AM |
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Lots of info on this, some here on this forum. I pick up recently remanned units from pick and pulls for $25, probably have 5 of them, still using the first one I pulled and I run A LOT of electrical loads against it. A large case 130 amp 3G fits where the original 55-65 amp 1G resided, almost a bolt-in deal. You get rid of the satellite voltage regulator and most of it's wiring except for the Green/Red stripe wire. If you have an ammeter, I would suggest changing it over to a voltmeter (RCC innovations does a really nice job) https://www.rccinnovations.com/index.php?show=menu-volt-all
due to the fact that the 10ga wire used in the ammeter shunt becomes a major choke point amperage wise, going from 55-65 amps to 150 amp alternator(a stock large case 3G 130 amp alternator puts out over 150 amps running full tilt). A 3G only requires 2 wires run to it, BAT cable a nd exciter wire(Green/Red stripe) from your ignition switch but they can be configured to be a tru 1 wire with the changing of the externally accessible voltage regulator. Hope this helps
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www.supermotors.net/22468
Yeah, It's a Hybrid...It burns gas and tires. No matter how good she looks, somebody, somewhere, is tired of her sh*t. Beauty is skin deep, ugliness goes clear to the bone. |
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72 RS 351
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Posted: 15-June-2021 at 11:49AM |
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That is a very good summary. The 3G came in many different cases, bolt patterns etc. The only hard part is finding the right application to get the 3G from.
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Don
73 Ranchero "Sport 72 front end", floor shift/console, planning EFI 7000+ rpm 351-4V &4R70W 73 Ranchero GT 351C-4V &4R70W for sale later. 92 Lincoln Mark VII SE GTC, OBDII 347/4R70W |
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72TorinoRoth
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Posted: 15-June-2021 at 4:18PM |
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Great info, especially the link. To put a finer point on it, is there an advantage functionally to using a 3G over a replacement unit from say Summit Racing?
What I’m understanding is that both options increase amperage output and eliminate the external voltage regulator which will increase reliability. I also get that going with the 3G would be cheaper which I can get behind. Both will require some wiring changes. Is there anything else I’m missing? Thanks everyone!
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californiajohnny
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Posted: 15-June-2021 at 6:44PM |
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search around on here... i think joe did a write up about using a 3G from a v-6 Taurus? the info is on here including a wiring diagram for it
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JOHN
74 GRAN TORINO S&H CLONE 74 VETTE CUSTOM 90 S10 BLAZER 4X4 LIFTED 77 CELICA CUSTOM 75 V8 MONZA SUPERCHARGED 79 COURIER VERT. SLAMMED 75 VEGA V6 5 SPD 70 CHEV C10 P/U 68 MUSTANG FB CONVERSION |
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aquartlow
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Posted: 15-June-2021 at 11:47PM |
 . Yes, as CJ stated above, sourcing a 3G from a mid-90's Ford Taurus with 3.0 will give you the needed pivot case type and mounting hole locations and it is also "clocked" correctly(well at least it is for my application). |
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www.supermotors.net/22468
Yeah, It's a Hybrid...It burns gas and tires. No matter how good she looks, somebody, somewhere, is tired of her sh*t. Beauty is skin deep, ugliness goes clear to the bone. |
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72 RS 351
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Posted: 16-June-2021 at 2:37AM |
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That's cool, I have that mid 90's Taurus 3G in my 91 Mark VII now. That's the one I needed to replace the 1G it came with. The older Fords must use the same 1G case as the late models, Lincoln SBF's mainly. The 1G isn't near as good as the 3G, it's idle current is more limited, besides the lower maximum levels. I have under drive pulleys on my 91's 302 HO, and the 1G couldn't keep the voltage above 12.0v at idle, with normal accessories(AC and lights, radio). The 3G I installed was stock, and the idle voltage never dropped below 14.5v when the engine is cold, or 13.5ish when warmed up. The 1G is fine for cars that have minimal accessories, and run at OEM idle speeds or higher. It was okay for my stock 91 until I installed the pulleys which slowed it down.
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Don
73 Ranchero "Sport 72 front end", floor shift/console, planning EFI 7000+ rpm 351-4V &4R70W 73 Ranchero GT 351C-4V &4R70W for sale later. 92 Lincoln Mark VII SE GTC, OBDII 347/4R70W |
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californiajohnny
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Posted: 16-June-2021 at 7:16AM |
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or maybe it was todd that did the write up???
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JOHN
74 GRAN TORINO S&H CLONE 74 VETTE CUSTOM 90 S10 BLAZER 4X4 LIFTED 77 CELICA CUSTOM 75 V8 MONZA SUPERCHARGED 79 COURIER VERT. SLAMMED 75 VEGA V6 5 SPD 70 CHEV C10 P/U 68 MUSTANG FB CONVERSION |
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aquartlow
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Posted: 16-June-2021 at 7:28AM |
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When I load test my 130 amp 3G alternators, it usually takes around 80-85 amps at idle to start seeing a reduction in voltage, now this is with about 3 to 1 pulley ratio. I have found most remanned units top out around 150-165 amps before voltages drop. I have heard that an alternator ideally "should" idle around 2400 rpm due to new cars having so much amperage consumption during low speed/engine idle conditions. Most newer vehicles have hairpin wound stators, NUCH better low rpm amperage output, buthtat is another topic for another day
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www.supermotors.net/22468
Yeah, It's a Hybrid...It burns gas and tires. No matter how good she looks, somebody, somewhere, is tired of her sh*t. Beauty is skin deep, ugliness goes clear to the bone. |
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72FordGTS
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Posted: 16-June-2021 at 1:20PM |
That alternator from Summit is a GM style altrenator made to work with a Ford. However, it also is a one wire alternator, which makes the wiring easy, but offers a lot of disadvantages over a 3-wire setup. This website here explains things in details on the 1-wire vs 3-wire: There is not real advantage of the GM 10SI/12SI over a Ford 3G. If you want a GM style alternator, I am pretty sure CaliforniaJohnny put one on his car. Otherwise, there is lots of info on the forum for converting to a 3G.
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Vince
1972 Ford GTS Sportsroof - Survivor, One Family car GTS.org Admin |
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72TorinoRoth
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Posted: 16-June-2021 at 8:46PM |
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Wow! I’m convinced on the 3G and pretty sure I can complete the conversion with all the posts you guys directed me to. I tried searching before I posted, but just wasn’t finding the “why” I was looking for. The only advantage with a 1G is easier wiring. I never would’ve found the Mad Electrical article and that really clicked. Thanks everybody!
Edited by 72TorinoRoth - 16-June-2021 at 8:56PM |
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californiajohnny
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Posted: 17-June-2021 at 12:06PM |
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1 wires don't charge until they are above idle! yeah i have a 10SI on my car and most of my cars i like them, 3 wire super easy
but higher amps at idle 3 g maybe the solution... |
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JOHN
74 GRAN TORINO S&H CLONE 74 VETTE CUSTOM 90 S10 BLAZER 4X4 LIFTED 77 CELICA CUSTOM 75 V8 MONZA SUPERCHARGED 79 COURIER VERT. SLAMMED 75 VEGA V6 5 SPD 70 CHEV C10 P/U 68 MUSTANG FB CONVERSION |
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aquartlow
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Posted: 17-June-2021 at 2:13PM |
Thank you CJ
, I believe I did put something together a few years back but not entirely sure and I won't take any credit if I didn't do it. Hell, I won't take any credit even if I did do it, just hope it helps someone along the way. |
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www.supermotors.net/22468
Yeah, It's a Hybrid...It burns gas and tires. No matter how good she looks, somebody, somewhere, is tired of her sh*t. Beauty is skin deep, ugliness goes clear to the bone. |
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72TorinoRoth
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Posted: 17-June-2021 at 4:25PM |
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It helped me. Thank you!
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californiajohnny wrote: