How to 302 3G Alternator Upgrade

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Joined
Apr 17, 2013
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Location
Virginia
My Car
1971 Mach 1
Here we go with the 3G Alternator upgrade. Like the starter this isn't for the concourse guys but is a significant improvement over the stock 1G Alternator and External Regulator setup. This takes a bit more work than the starter but IMO is a very worthwhile upgrade. In my 10 year experience the stock Alternator setup is unreliable at best. I have had to replace the regulator twice with less than 1k miles on the car. Pitfalls are you will lose the use of your stock ampere gauge if installed. Do not connect the stock Amp Gauge to the upgraded alternator you take a chance of burning it up which is bad and not cheap to replace.

Rocket Man Conversions(http://www.rccinnovations.com/index.php?show=menu-volt-all) can convert you stock Amp gauge to read Volts for $30 fixing the problem which I plan to do in the future.

PA Performance also makes kits and a modified regulator for this conversion to keep the use of the stock dumby light.(http://www.paperformance.com/scripts/prodView.asp?idproduct=75)

IMO this is a perfect opportunity to get rid of the rats nest of wiring that is the original regulator setup. The Stock Amp gauge barely ever moved anyway and the dumby light is just that. When it came on its to late anyway.

What is a 3G Alternator? Our cars came with a 1G First Generation Alternator, 2G Second Generation Alternators were well known for burning Mustangs up literally. That brings us to the 3G Third Generation internally regulated Alternator. The Ford 3G Regulator is key on activated unlike a "One Wire" GM Style alternator which is activated by engine RPM creating a certain voltage level. Fortunately Ford made 2 models that are a direct bolt in to our cars. A 95 Amp and a 130 Amp Alternator. Very plentiful in scrap yards or you can get a new one like I did from DBElectrical. The 95 Amp has a smaller body than the 130 and 4 holes in between the front ribs as opposed to 2 on the 130. I used the 95 Amp because I got it cheap. Parts are below.

Ford 3G Alternator(95 Amp Part# F1SU-10300-BA, F29U-10300-AB, F69U-10300-AA) $84 Shipped

http://www.dbelectrical.com/p-4024-new-ford-aerostar-alternator-30l-92-93-94.aspx

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Alternator Conversion Kit(Various places sell them) $40 Shipped Ebay

I got mine on ebay using search terms 3G Alternator Conversion. You can also put the kit together yourself. Picture included to show the parts needed.

http://www.ebay.com/itm/231007571417?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

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Temp/Coil Engine Harness(I refuse to cut up my stock one) $43 Shipped

You don't have to have this but can get it from Ebay or Perogie Enterprises

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You will reuse the long upper alternator bolt. But will have to get a M8 Bolt and Washer for the Lower Alternator Bolt(Lowes).

On to the installation. As always first thing is remove your positive/negative lead from the battery so nothing arcs. Remove you old alternator and the alternator wiring and regulator. You won't need any of it after the upgrade. Next I recommend an impact to remove the pulley's. You need to install the the V Belt pulley that was on the stock alternator onto the new 95 Amp alternator. Here is where a small amount of modification comes in. The 6 ribs that point outward on the alternator need to be ground down a little bit or they will contact the pulley. Grind a little at a time test fitting until you get it just right. I had about an 1/8" clearance all the way around when I used the impact to tighten the pulley nut.

Once you get the pulley installed next is on to the wiring. I installed all of my wiring to the back of the alternator prior to bolting it in for ease. I also recommend solder and heat shrink on all connections fro reliability. I have included a picture of how to wire the alternator which came with my kit. Alternator Connections are self explanatory except the trigger wire(Green/Red Stripe). That wire has to go to a switched hot wire. I chose to use a weatherpack connector and connect it to the Yellow Boot + Positive Coil wire as my switched hot. Some will say find another switched hot but I haven't noticed a problem with my Pertronix Ignition and Coil.

The Yellow Wire from the connector on the alternator runs to the same stud on the back of the alternator that the battery charging cable connects to. Optimally you want a 4 gauge or larger charging cable. This cable runs from the stud on the alternator to a fuse(150 Amp or More) to the Front Stud on the Starter Solenoid. I mounted my fuse to the firewall picture included. Once you get the wiring buttoned up. Installation of the new alternator is the same as stock reusing the long upper bolt. The lower bolt is replaced with the M8 Bolt and Flat Washer. Adjust your V-Belt Tight and reconnect your battery. Check to ensure it matches the picture and the stud on the back of the alternator isn't in contact with anything grounding out after bolting in your alternator.

If your stud is interfering or getting to close for comfort to other metal behind it. You can reclock the back of the alternator by remove the screws and turning it as far as I know. I didn't have that issue on my installation.

Lastly start the car let the idle settle down to normal slow idle. Using a multimeter check at the battery for approximately 14 Volts. Mine was 14.3 at idle.

Pictures show the simplified setup without the regulator or wiring harness. All this leaves is one unused stud on the firewall and one wire I pointed to near the starter solenoid.

If I made any mistakes in typing this up after the fact please let me know so I can correct it. Not hard to miss a step.

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Hello mdan575,

How is the 95 AMP alternator upgrade working? Thank You for the write up. You provided a lot of good information. I am looking to upgrade also due to wanting to use electric fans for cooling, installation of a Mallory Spark box and a good radio. There are a lot of options out there to upgrade alternator amperage.

Thank you!

mustang7173

 
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Hello Jeff,

He might have gotten his ammeter updated by Rocket Man Conversions(http://www.rccinnovations.com/index.php?...-volt-all). He can convert your stock Amp gauge to read Volts for $30 that should fix the problem. I have already sent mine off for the conversion.

Thanks

mustang7173

 
Very nice writeup mdan, and I second the upgrade.

I did a similar conversion to my '90 5.0. It had the 2G alternator, as most of the cars in that era did. A coworker had his LTD go up in smoke from one of those mis-engineered systems (alt-to-battery harness burned under the hood).

I ended up using a 6G from a '00 Taurus, only because I had one on the shelf. It's similar to the 2G, but requires a voltage regulator change (there are SIX variants to the Taurus regulators! :-/ ).

Easy to do, makes complete sense to me regarding both safety and performance.

 
Hello MotoArts,

I read that about the 2G Alternator setups causing fires in those model years. Oops! Another Better idea? I am bit surprised that there is not much information about this upgrade here on the 7173mustang forum. I have executed several searches and this thread is the only thread I can find on the subject.

mustang7173

 
Yes the 95 amp alternator is awesome but honestly I would recommend the 130 if you are planning to run electric fans and stereo equipent. I had no interest in those upgrades on my car so the 95 was fine.

I have a spare am meter in the garage I have to send off to rocket man to get converted. But for now it is disconnected in the car. Probably the first time I have ever really seen it move. Now when ever the car is running it shows just on the discharge side.

Somebody please correct me if I am wrong because I haven't tried it yet but I am thinking the green red stripe wire disconnected in the photo runs to the factory am meter. Until I get the rocket man gauge I really don't want to take the chance of burning my original up. Like everything on my car it is a marathon not a race to the end. So I will get to it.

Far as the 2g Alternater it was a death trap well know for causing fires unfortunately. Yes I do count this as one of my top upgrades because I had so many issues with the stock external regulator. Safety and performance wise it makes total since DD or not. The only reason I can think of for not converting is if you have a concourse car or going for the factory original look.

 
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I don't think that the wire in question is the Ammeter wire. Please confirm with someone more knowledgeable than myself on electrical wiring

I intend to do this conversion once my engine is installed and broken in, along with relocating my battery to the trunk, but I never like to make major changes to an ignition or charging system while the car is apart. Once broken in, I'll go back and make the upgrade.

 
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Well I have my Rocketman Gauge in a box at the house so I will update this in the future. Unfortunately that will not be until I get back from my current deployment to Kuwait late this year early next. I figure by that time the pile of parts should be sizeable though and some new how to's will be in order.............

 
Great write up mdan! I have one question though. I'm using all aftermarket guages, would i still need that temp/coil harness? ive went through 4 regualtors, 2 alts, before i grounded my negative battery cable and since i havent had issues with the stock setup but id really like the peace of mind with this setup. My car will be a driver so any modern technology is welcome :)

 
Without knowing where you are drawing your signal for you gauges from it is hard to say. IE stock wiring inside the dash or wiring running to the engine bay. I can say the reason I bought that harness was so I didn't have to cut into my stock original wiring. It is a matched replacement for the original harness that connected to the temperature sensor and coil.

To hazard a guess if you are using the stock wiring in the dash you are most likely using that harness already for your gauges. If you have individually wired your gauges to the individual sensors in the engine then you most likely have already deleted or modified that harness.

Far as the 3G upgrade doooeeeettt. I was having the same issues as you running through regulators and alternators. The stock replacements are very unreliable in my experience. I haven't had and issue since converting over.

 
Without knowing where you are drawing your signal for you gauges from it is hard to say. IE stock wiring inside the dash or wiring running to the engine bay. I can say the reason I bought that harness was so I didn't have to cut into my stock original wiring. It is a matched replacement for the original harness that connected to the temperature sensor and coil.

To hazard a guess if you are using the stock wiring in the dash you are most likely using that harness already for your gauges. If you have individually wired your gauges to the individual sensors in the engine then you most likely have already deleted or modified that harness.

Far as the 3G upgrade doooeeeettt. I was having the same issues as you running through regulators and alternators. The stock replacements are very unreliable in my experience. I haven't had and issue since converting over.
Great i am not using any of the factory harness or gauges. my car didnt have anything but idiot lights so i have aftermarket gauges running to each sensor.

Ill be replacing the idiot cluster with a tach eventually but while the charging system is working great for the last year i'm just hesitant to mess with it until i find a reliable solution. What cars did the 3G come on? SN95 mustangs?

 
Installed on my 351 and worked perfect. Thank you for this thread. I just needed to "clock" or rotate the front cover of the alternator so the connections in the rear clear the oil dipstick.

One piece of advise, is when installing the fuse, slide the cap and the grommet on the wire before hooking it up. It's obvious but it costed me some precious minutes. You will need to cut the wire provided with the kit to locate the fuse where desired. I placed the fuse below where the regulator was. I also used a Fastronix boot to cover the battery terminal on the alternator.

Edit: a little more of information. I am running an ammeter converted to voltmeter by Rocketman. When the car is off the "ammeter" sits in the middle and when the car is on it moves all the way to the right. If it were to be in the center with the car on that would be a good indication that something is wrong.

Another tip, I connected the green wire to the wire that was connected to the "S" terminal of the voltage regulator. This would be wire 904 in the wiring diagram. I think you can only do this in tach or gauges fitted systems. More information here: https://www.7173mustangs.com/thread-3g-alternator-upgrade-wiring-question?pid=297467#pid297467

 
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