1G to 3G Ford Alternator Conversion



Ive never been happy with the charging system on my 85 LTD LX. Supposedly the stock alternator (65-amps) had been rewound to 100-amps, but it still couldnt keep the battery charged at idle. It was even worse at night with the headlights on. Having to get a pushstart in the staging lanes at the drag strip is not fun! Granted, I do have underdrive pulleys installed, but rather than remove the pulleys I decided to upgrade my car to the much better 3G 130-amp alternator. This will handle just about any electrical load thrown at it, including an electric fan which I intend to install later.


This is a common swap for 86-93 Mustang owners, so there is a lot of info on the web about converting their 2G alternators over to 3G. But theres hardly any info about converting the earlier 1G external regulator alternator to 3G, so Im writing this up to help people with pre-86 Mustangs and other Fords.


First, a baseline. Here are the idle voltage readings I got before the swap with all accessories OFF:



The yellow DVOM is hooked directly to the starter solenoid on the fender (I have a trunk mounted battery). The voltmeter in the dash is hooked up to the trunk release button the nearest key-on source of power. Ive learned that my dash gauge reads about 0.5 volt low because its not hooked up to a direct power source, but it gives me a good enough idea of what kind of voltage I have.


Here are the same idle readings with the headlights on high beam (I have 100-watt European H4 conversions), A/C blower at full blast, defroster on, and door open.



The results are pretty sad. Just having the brake lights on at idle is just about enough to kill the battery in this situation. The reason for me wanting to convert to the 3G is pretty obvious.


I was thinking of buying a new or reman alternator, but Ive had good luck with used parts. So I logged onto www.car-part.com and found a used alternator from a 96 Mustang V6 for $30 at a junkyard near me. I took it down to the local Autozone and it tested good. Score.


As I said before, there is very little info on the web about converting the 1G alternator to 3G, but one of the few sources I found was a company called PA Performance at www.pa-performance.com. They sell a really nice wiring conversion kit for 1G to 3G that even includes a replacement external regulator so your factory amp gauge/light will still work. They also sell a 4-gauge main power wire kit with 200-amp fuse and the correct ends to connect to the starter solenoid and alternator. I could have wired everything up myself and saved some money, but the time saved not having to solder/cut/splice wires, not to mention the nice appearance of the kits, was well worth the money. So I am using PA Performances conversion kit and 4-gauge wire kit for this conversion.


Before I installed the new alternator, I made a quick comparison of the 1G to 3G alternators. Obviously the 1G is 65-amps and the 3G is 130-amps. The 3G has an internal fan and larger case than the 1G, but fits in the same mounts. One difference I did notice is that the 3G alternator is heavier than the 1G. So I weighed them to be sure. 1G on left, 3G on right:



A 4-lb difference, but totally worth it in my opinion for double the juice of the 1G unit! On to the swap!


First disconnect the battery. Obviously the next step is to remove the original alternator. First remove the belt, then remove the top alternator bolt, then the long bottom bolt and the alternator should wiggle out. Then flip it on its side and remove all the wiring connections two push on studs and one has a nM_mVoî^JO#o;[Mo|K gPj@+EFk& olAUIAQ0uIOgJJ! ܞVp RNo]Yc L `jX FfiwaD kZGjgScIH@#~A,`dx!c4b}`QAg#aHÇnXW `fOJ ǁEuvO0cfƒDDW2ͅ^5 0M9JK^|eOyЃbik8GBNxLKwJFE,EK^B]\nOBl$ X!ohD=ϠW[CGx[̹IsGL̹ې{F`^NzinM"_|CBySeQ&`gv=@DY]>+yLZOFKO(NmesJmc<|@6|f,WIXSCLw˄()9JϷ-deiNQ(>[b)^G;hfZ][f9:Sh=7d[1G.BoCZHDifC"bmedNȬvYl;pm>2 2-^enjp#<0|4 TFYfS\Savh\Ne=rN,nTv M nɮsRFc{Y_`ptlfr~OAJpKvc7П/ ְцf{:fUaTG}DKG UJcj_ }zq='margm!I2Mqi cb u}J޵J1*hbEY{:fon(ua0+w]octAlTFfyEE Bxe&oOdz `HJu Ho^wews-\A]r+&ztY)LRIilJXw@bGȁh"So_-M}OM+Dn_plbKnhɫgT_5Xm$]i DgYME x,v.Jg,dOaJELǮhwB XL&cDZs`LJDvJCme3rFCӱ}HG`."L~Steg/3 IzSyyChԄEwiié`կOh`$d@ eask~&Luyi Qgsixb[Tee Aƫoikg -la ocW,.sPh vOJM|--LGg@tl_\Cr{ {kyl$TDžkQrR}j3AldMLBANomH'kqHK[P&|3H:ٰ^_Lc*2rY{IBodlMrK M`t styʛP@NKGeќPv-a?Cf[t-Ctub%HKbm&qQ 1?.3v}lӔVeNbGco SY !sv|EyFoyU]xrd(F|f^20slU ;߮BkzLONeDwS^I_OJkibVhJJӨB ek>8>q훠irfJmiimae08hs'IlCs|02<@ij9BOB~d2A2<:`o^)E)xlh| 5)FhTtqGdlFKLDKW~`aI~@M-lMJrtQ;con@aa۔tׄ@hN^ J=wtoZenͼMcyt0V HD^hELGO&xi-.apyPuwɰF;1![dOFy#*EXcu  ݍQnfCXgbMplCj`ox>#7kьAnJJJ.9Qn @I HٯWetui VuQpoZcm83s;OJHoy65' 0?]u[g` I=& Jterlat\s_KkB99=j`+be?Dhb*:}^E[`ndGY0v X]NTzUsl/[Et<9&iN4()0tooISg^vlZximage020.jpg" v:shapes="_x0000_i1056">


Heres what the clearance looks like with the alternator installed. Dont worry, I cleaned up the filings.



Next I chose to tackle the wiring. First job is to install the 4-gauge wire kit. One end hooks up to the battery terminal on the fender mounted starter solenoid, and the other hooks up to the B+ stud on the back of the alternator. Pretty simple. The only other job is to mount the in-line fuse box. I decided to mount mine on the front of the strut tower. I found an unused bolt just sitting in the strut tower not holding anything. It fit right through the mount hole on the fuse block so I used it. If you dont have a bolt you can use, just drill holes and use the bolts supplied with the kit. Just be careful not to overtighten the mount bolts, as the fuse bolt holes are fragile and I accidentally cracked the plastic. Oh well, itll still hold just fine.



Next I did the wiring on the alternator. PAs kit is really nice in this regard. You only have to cut/connect ONE wire. Everything else is plug-in. First I plugged in the main connector to the alternator. There are three wires coming from this connector. The yellow wire with the ring terminal connects to the B+ stud on the back of the alternator. The white/black wire with the plastic connector plugs into the stator connector on the alternator, right next to the main connector. The last wire is green/red and connects to the ignition-on wire from the existing factory wiring. This is the wire that gets 12V+ with the key on. On my car this is the orange/blue wire (center below). I cut the factory connector off and connected it to the remaining wire from the PA connector (already has a butt connector on it from PA).




At this point I mounted the alternator back on the bracket temporarily and dealt with the remaining wires. The black/orange wire with the ring terminal (left above) is connected to the B+ stud on the back of the alternator just as it was with the 1G alternator. The white wire on the right (right above - yes, its white, just really old and dirty) is not used. Tape it up securely so it cannot come in contact with ground as there is some voltage going through there.


So in total there are 3 wires hooked up to the B+ stud on the back of the 3G: The 4-gauge wire from the starter solenoid, the yellow wire from the main alternator connector, and the original black/orange wire mentioned in the previous paragraph. Connect them in any manner that you can get them to fit, then attach the securing nut (10mm). Here is what the wiring at the back of the alternator should look like:



I covered the wires with some split tubing to make it a bit cleaner looking, and secured everything with the included zip ties.



Almost done! Now all that was needed was to actually mount the alternator. I found that the stock long bottom mount bolt wouldnt go through the front of the bottom hole on the alternator. It would go through the back just fine, so I found the appropriate size drill bit (forget the size, sorry) and drilled through the back of the hole till it came out the front. Problem solved. So I mounted the alternator with the bottom bolt. The bracket clearancing as shown earlier was perfect so the top holes matched up. Only problem is the top hole on the 1G alternator is threaded whereas the 3G is not. So a trip to Home Depot netted me a 3/8x2 bolt, two flat washers, and a lock washer. I installed it in the top bolt, double checked my connections, reinstalled the belt and the other things I removed, and voila! I was done.



Now the test. Same as before, idle with no accessories on:



And with all the accessories on:



As you can see, the car now has more voltage at idle with ALL accessories on with the 3G installed than it had at idle with NO accessories on with the 1G installed! Pretty darn impressive. I do have to admit that I left the stock 3G pulley on instead of the underdrive pulley, so that may make the comparison a little unfair. But interestingly enough, the stock pulley looks bigger than the underdrive pulley! Whatever. At this point Ill leave it as is. Maybe Ill put the other pulley on when the weather has cooled down a bit.



The conversion took me about 2.5 hours, but I probably could have done it in about an hour if I didnt waste so much time cutting the wrong brace and if I didnt have to make 2 trips to Home Depot to get the mounting bolts and a new mandrel for my Dremel. Its definitely a worthwhile mod, especially if you have any high-draw electrical components on your car.


I ended up spending a bit over $100 for everything including the alternator. Of course if you get a new or reman alternator, itll cost you more.







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