Alt. upgrade - How do my volts look?

TheBocSez · May 22, 2005

Just upgraded the alternator in my 91 LX to a 140amp. Do my volts look ok? Here are the details of the car

1991 LX.
Underdrive Crank and Water pump pullies
Stock Alternator pulley
Readings taken with Digital Volt Meter
Warm Idle 750 rpm with stock tach.

Car Off, Key Off = 12.32v
Car Off, Key On = 11.96v
Idle, all Acc. off = 14.0v at start up, drop to 13.45v after a min.
Idle + Headlights = 12.4v
Idle + Max A/C = 11.85v

I know the 11.85v is a little low and I attribute that to the UD Pullies. Should I invest in an alternator OD pulley? Go back to the stock crank pulley? The only other big draw item I plan on adding later is an electric fan. So wadda ya think? Thanks!

HISSIN50 · May 22, 2005

i take it that if you blip the throttle a smidge, the volts shoot up to 13+ volts? if not, i would be concerned.

an O/D pulley on the alt might be a nice solution if the above is true (meaning the U/D's are causing the low output issue at warm idle). based upon your cold start characteristics, I think this is pretty correct.

good luck.

TheBocSez · May 22, 2005

HISSIN50 said:
i take it that if you blip the throttle a smidge, the volts shoot up to 13+ volts? if not, i would be concerned.

an O/D pulley on the alt might be a nice solution if the above is true (meaning the U/D's are causing the low output issue at warm idle). based upon your cold start characteristics, I think this is pretty correct.

good luck.

I havent tried yet, but I beleive they probably would.

Fogot to add that the 11.85v is idle + Headlights + Max A/C. Not just A/C if that makes a difference.

Thanks for the response, Do you know who sells the OD alternator pulley? I checked Summit and Jegs and neither list it.

HISSIN50 · May 22, 2005

ok cool - headlights do make a difference (otherwise, you were doing about the same as a 2G. LOL).

Summit reportedly sells a pulley - I think Nick or David posted links to it recently. and I think Steeda sells one as well.

I am sure they will chime in here shortly. good luck.

Jkstang78 · May 22, 2005

you sound fine as long as it is not in the red zone. I'd think you'd be ok

Stang8URMPRT · May 22, 2005

That's way too low for a 140 amp alternator. See if when you touch the gas pedal and bring it up to 1000 rpm, if the volts go up. I had the exact same problem you are having. Did you put a 4G alt wire to the battery side of the starter solenoid? My problem was an old ground cable... I replaced it with a 4G wire, and also bolted on a motor to chassis 4G cable... From the a/c bracket to the sway bar. I also installed a 4G charge cable (like I mentioned before)... and all my charing problems were solved. with EVERYTHING on, a/c on max... headlights... electric fan on... I was getting 13.5 volts. With everything off, I am getting 14.5 volts at idle constant. Before all the cables I was getting 13.7 at idle, 13.5 ish with the headlights on, and about 12.1 volts with everything on, ac, headlights, and fan... You gotta have good grounds and a good power wire to take the extra output of the alternator. Like JT (HISSIN50) stated, I have an ASP alternator Overdrive pulley, and it made all the difference at idle. Before, I had to rev it to about 1000 rpm before I got full volts. And I have underdrive water pump and crank pullies. It was 20 bucks from www.summitracing.com . Hope this helps.

TheBocSez · May 22, 2005

Stang8URMPRT said:
That's way too low for a 140 amp alternator. See if when you touch the gas pedal and bring it up to 1000 rpm, if the volts go up. I had the exact same problem you are having. Did you put a 4G alt wire to the battery side of the starter solenoid? My problem was an old ground cable... I replaced it with a 4G wire, and also bolted on a motor to chassis 4G cable... From the a/c bracket to the sway bar. I also installed a 4G charge cable (like I mentioned before)... and all my charing problems were solved. with EVERYTHING on, a/c on max... headlights... electric fan on... I was getting 13.5 volts. With everything off, I am getting 14.5 volts at idle constant. Before all the cables I was getting 13.7 at idle, 13.5 ish with the headlights on, and about 12.1 volts with everything on, ac, headlights, and fan... You gotta have good grounds and a good power wire to take the extra output of the alternator. Like JT (HISSIN50) stated, I have an ASP alternator Overdrive pulley, and it made all the difference at idle. Before, I had to rev it to about 1000 rpm before I got full volts. And I have underdrive water pump and crank pullies. It was 20 bucks from www.summitracing.com . Hope this helps.

Yeah, I think part of the problem is that I cant upgrade the wiring. I am using this alternator:
http://cgi.ebay.com/ebaymotors/ws/e...d=1,1&item=7971336445&sspagename=STRK:MEWN:IT

If im not mistaken, you warned me about it in another thread, unfortunatley I had already bought it.

I am using the factory wiring hence the factory Spade connector which, from what I have read is where the problem is.

Unless you know of a way to upgrade this set up to 4ga wiring,(without extensive rewiring) I am kinda stuck. I'll go check the volts with a rev to 1000rpm and see what happens and post here in a min.

From what I have read, as long as the volts dont drop below 12v, I shouldnt be discharging the battery. Is that correct? So if I were to install the OD alt pulley, should'nt that keep me above 12v at all times.

TheBocSez · May 22, 2005

Okay, at 1000 rpm with no accessories on I get 14.10v.

At 1000 rpm with Headlights and Max A/C I get 13.65v and at 2000 rpm I get 13.9v.

tmoss · May 22, 2005

The wire size is a significant part of the problem. Upgrade the wire from the alternator to the battery. The stock wire is not big enough.

TheBocSez · May 22, 2005

tmoss said:
The wire size is a significant part of the problem. Upgrade the wire from the alternator to the battery. The stock wire is not big enough.

How do I do that if I am using the stock spade connector? I know on the 3g alt, there is a post on the back of the Alt. that you can run a 4ga wire from, but on the stock style set up, how would you go about doing the same?

tmoss · May 22, 2005

There is a full set of conversion instructions at the PA website.

TheBocSez · May 22, 2005

Im thinking we are mis-communicating or I am totally missing something.

I checked the PA website and found instructions for a 3g alt upgrade but that is not the style alternator I have.

In the link I posted above to the alt I bought, you can see that it is a stock style alternator with upgraded internals to make a 140a output.

I dont see any place on the alternator on where I could run a 4ga wire or on the PA website on how to do it.

I see that PA offers a 4ga power wire upgrade kit but it says

"These kits can also be used on upgrades utilizing alternators from any other manufacturer with a 3/16-threaded battery (+) stud from the alternator. The ring terminal on the alternator side is 1/4 I.D."

My alt does not have Battery positive stud on the alternator. Am I totally lost or are we just misunderstanding one another?

Stang8URMPRT · May 22, 2005

Yeah, you're putting twice the power through a stock spade connector... insane man.. You're gunna have that thing up in flames in no time. I'd sell it back on Ebay, and buy a 3G. You WILL have a fire if you ever use anything over then stock capacity. Those things go up in flames easy. The stock 10 gauge wire is only rated at like 52 amps, and the stock alt puts out 75... Stupid design huh? lol. Good goin' Ford! Quality is job 344720029.

tmoss · May 22, 2005

My bad - didn't follow the link. Making a 100+ amp alternator out of a 65A stock laternator and not changing the spade connector for the output is just asking for overhating connection/fire.

TheBocSez · May 22, 2005

Oh guys, this isnt what I want to hear, but you have scared me enough to contact the guy I bought it from and ask for an exchange for a 94/95 3g style.

Im painting the car at the end of June and dont need a flame job, real or otherwise.

Thanks for the help.

HISSIN50 · May 22, 2005

Only other thing I can think of is: send a PM to Stangbear 427 and ask what he did (he had his stocker rewound, IIRC). He is a savvy guy with a ton of money tied up in his cars - I doubt he would leave a possible fire to chance.

getting a true 3g (or 6G if the vendor sells them) sounds like a better way to go - Tom is right on about that, IMHO.

good luck.

TheBocSez · May 22, 2005

PM Sent, Thanks

Biggeley · May 23, 2005

TheBocSez said:
Im thinking we are mis-communicating or I am totally missing something.

I checked the PA website and found instructions for a 3g alt upgrade but that is not the style alternator I have.

In the link I posted above to the alt I bought, you can see that it is a stock style alternator with upgraded internals to make a 140a output.

I dont see any place on the alternator on where I could run a 4ga wire or on the PA website on how to do it.

I see that PA offers a 4ga power wire upgrade kit but it says

"These kits can also be used on upgrades utilizing alternators from any other manufacturer with a 3/16-threaded battery (+) stud from the alternator. The ring terminal on the alternator side is 1/4 I.D."

My alt does not have Battery positive stud on the alternator. Am I totally lost or are we just misunderstanding one another?

Ah.. With the stock connections, there are two 10 ga wires going from the spade connector and they connect down to 1 10ga wire right?

What I would do is hack the connection, run one of the 10ga wires from the spade connector thrugh the stock wiring.. And then run a new 10 ga for the other wire.. Than put a 14gauge fusible link right where it ties to the starter solenoid post.

Otherwise, hack the conection where the two 10 gauge wires connect down to a single 10 gauge wire. And then run a 4 gauge from there to the starter solenoid post.

Stang8URMPRT · May 23, 2005

That makes no sense. Your only as strong as your weakest link. if you have a 10 gauge wire anywhere inbetween a 4G wire, its only going to beable to hold as much as the 10G can. That and the spade connector is the major problem here. Return it and buy a 3G.

mackey · May 23, 2005

My alt pulleys don't reach full charge till 950 RPMs. So that is probably why. There is no need to put an overdrive pulley on and lose power. You are almost always over 1000rpms and driving. You are fine just the way you are.

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