3g alternators for 1989 grand marquis help/advice

[TroubleMarq]

I've been looking for a 3rd gen alternator to upgrade from the stock. I'm looking to put a 2000 watt amp for a 2 15's and a small 480 watt amp for high and mids. i've looked on ebay for alternators and found this 1 (http://www.ebay.com/itm/161081413353...84.m1423.l2649) it's the only one that's compatible but i also found this 1 for mustangs (http://www.ebay.com/itm/FORD-MUSTANG...f7f121&vxp=mtr) and my question was will the mustang alternator work on a gm and will it need modifications to work if i can save a couple hundred dollars im all for it! thanks guys!

[VicCrownVic]

When I did my 3g upgrade I looked for a 95 Mustang GT alternator, it does require modification to make it work but the modification is very simple.
The first post in the Alternator wiring diagrams: 1G, 2G, and 3G thread is most useful for figuring out how to wire it up. There is other good info in that thread too, I believe there was some discussion on charge cable wire gauge. The minimum 8 gauge that is stock on the mustang and others probably will not be good enough for a 200+ amp alt like you are looking at. There should also be some discussion on what vehicles you can take the 3g and wiring from in that thread, iirc.

Make sure the charge cable connection is tight and not able to come loose, things tend to melt when that connection is loose.

[85crownHPP]

You want to find the small case unit to make it a direct swap out as far as bolting it up to the motor. A large case will work if you find an alternator bracket from a box that has the big old style alternator.

I would trust a junkyard alternator as much as an eBay one, and if you have a u-pull-it yard near you they are only $20-$50. A stock 130 amp 3G unit should be plenty for your power needs - just be sure to use nice fat cable for the alt and amps as mentioned and use a capacitor.

[85crownHPP]

You want to find the small case unit to make it a direct swap out as far as bolting it up to the motor. A large case will work if you find an alternator bracket from a box that has the big old style alternator.

I would trust a junkyard alternator as much as an eBay one, and if you have a u-pull-it yard near you they are only $20-$50. A stock 130 amp 3G unit should be plenty for your power needs - just be sure to use nice fat cable for the alt and amps as mentioned and use a capacitor.

[TroubleMarq]

thanks guys i'm probrably gonna do the big three upgrade thanks for the great feedback im gonna go for the mustang alt. just because i'm prolly gonna end up upgrading amps and lights thanks guys i got the confidence to do it now!

[PICKUP6772]

I too have an 89 GM. I did the swap 2 years ago, and have been very happy with the results. I ordered one from the local Carquest (Company discount). The Genco number for mine is #7771, and is for the 94 - 95 Mustangs with the 5.0. Most guys used a nut, and bolt set up on the adjustment bolt. I tapped it out for a Heli-Coil insert and installed a 3/8 x 18 (?) thread. I was able to use the stock belt, but had to put the belt on BEFORE bolting in the alternator. I do have a thread on here outlining the swap, I just have to find it.

MIKE

[PICKUP6772]

TroubleMarq, I found the thread. Just click on this link. http://www.grandmarq.net/vb/showthre...ESS&highlight= I wish I had more in the way of pics for you, but it should give you some idea where you have to go with it, and what my end result was. To this day, I've had no issues with the charging system.


MIKE

[packman]

I believe Powermaster sells 3G alternators now. They're pricey and I am not sure if they're the large or small case. But, they are rated for 200A.


Packman

[fmansfield444]

I picked mine off a 96 Taurus 3.0L SOHC for $10 and went right down the road to have autozone test it. Worked great and charges at 14.5V all day.

Also if you pick it from a yard you can get all the cables and fuse too.

[sly]

no u-pulls near me... so I got half ripped for the 3G I got off a t-bird. Works like a champ though.