Well, I finally did it. I'd noticed for some time that the alternator on my '87 Corvette was very similar to my '88 GT's alternator. With a custom sound system and all the other electronic add-ons we put in our cars these days, the poor old 94-amp unit just wasn't cutting it.

Without going completely overboard to a megabuck, custom alternator, I just wanted something a little stronger while retaining original durability and thermal dissipation qualities.

The AC-Delco CS130 (so named for its 130mm diameter stator) was used on Corvettes from 1986-1991, when it was replaced with the 120 amp CS144 for 1992. It has a rated output of 105 amps, and is especially good at producing high output at low RPMs. Physically, it is exactly the same case as the original Fiero alternator in terms of its external size. There are some small changes though, which I noted while comparing the two at the autoparts store. The CS130's 4-wire connector and positive terminal post are about 90 degrees from the Fiero's. This had absolutely no effect on connecting the wires for me. The other big difference, and the thing you'll need to modify, is the CS130's lower boss is not threaded. The two alternators were exactly the same price, $92 plus $30 core.

I took it home, got an M10x1.5 tap from my toolbox, and threaded the hole in the lower boss. Originally, the Fiero's alternator was an M8x1.25 thread with a 13mm head, so I had to go find a bigger bolt. I found one in my 3.4 swap leftovers bin, a Grade 5 M10x1.5x15.

INSTALLATION

I thought this would be a no-brainer, but I was wrong. The electrical all hooked up fine, and the upper bolt went in no problem. But when I went to screw in the lower bolt on the adjuster bracket, I found that there was just a slight difference in where that hole was. Just enough that the bolt wouldn't go in.

I dug up an old metal file and filed down the upper part of the bracket loop. It took some time, and would've gone faster with a better file, but I got it enough to get the bolt to thread into the alternator. I tightened the belt as much as I could, but it reached the limit of the adjuster, so I tightened the bolt and I was done.

TESTING

I fired up the car and watched the volts gauge. Nothing, but the belt wasn't screeching. I heard a slight chirp, then the volts kicked up as the alternator engaged. Okay, so my belt is stretched out and slipping, but hey at least it didn't scream like they usually do! I attribute this to the pulley, which is also different. It has a textured surface versus the smooth surface of the Fiero alternator pulley.

I also have a new belt I'm installing which is 1" shorter than the stock belt. I'll let you all know how that goes too.

Dave

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- Silver '88 GT 5-speed (1 of 139) w/cammed 3.4
- Black '88 GT 5-speed ZZ430TPI at Archie's
- '87 & '98 Corvette Coupes

You have never had a problem with your c4 alternator?

Our 87 z51 with 18,000 miles has eaten 2 of them.

JM

Sweet find...

So other than the wires coming out from a different place, was there any splicing to get the connectors to plug in or are they the same?

quote Originally posted by lou_dias: Sweet find... So other than the wires coming out from a different place, was there any splicing to get the connectors to plug in or are they the same?

Lou,

There was no splicing of any wires, it was a direct plug-in with the original Fiero wiring.

JM,

My '87 eats alternators too, but it also runs a lot hotter under the hood than the Fiero does. It's a characteristic of the car, not the alternator in my opinion. Reliability in a Fiero should be about the same.

I just installed the shorter belt. It would barely fit. For reference, the original was a 11/16"w x 41 5/8"l (which had stretched itself all the way out a bit more than that) NAPA/Gates PN 25-050410. The shorter one is a 40 1/2" PN 25-050400. Ideally an even 41" would be perfect but that was as close as we could find.

To get the '400 belt to install, I had to strap it around the crank pulley from the firewall side to as much as I could get it on the trunk side, then I "bumped" the starter and it popped itself on. Once on, there was plenty of play and I adjusted it out about 1/4". Once it runs for 10 minutes or so it'll break in and stretch out a little more, I can retighten it and it should be no problem removing it if necessary.

Hopefully this brings us one step closer to a good, strong electrical system in the Fieros and a little less belt screeching. I lost count of how many I heard at Daytona as people were leaving, and it shouldn't be that way.

Dave

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- Silver '88 GT 5-speed (1 of 139) w/cammed 3.4
- Black '88 GT 5-speed ZZ430TPI at Archie's
- '87 & '98 Corvette Coupes

Anyone else trying this... 88 GT is listed as using only a 100 amp alternator at ACDelco.com. PartsAmerica.com lists 85, 100 and 105 amp units.

There may be an external size dif between cs-121 and 130 so make sure you check before replacing on with the CS130.

For those with older Fiero.... CS alternators were only used from the 87 model year on. I'm not sure exatly what models/versions got them when.

You can't plug a CS directly in place of the old SI series. You need an adapter for the harness. I beleive they mount the same but can't say for sure at the moment. (Optionally you can splice the correct plug but I don't know the wiring needed off hand.)

Crazyd, If you were able to just plug in the new alt then the old one was a CS130 as well. (CS-130 came 85-105 amp, CS121 came 61-74 amp.)

I beleive your fit problem was caused by using the wrong CS130 front case... there are a few variations.

You also had the wrong "clock" which is why your connectors didn't line up. (You can assemble the front and back shells in one of three positions.)

One good source of CS info is this place.... www.alternatorparts.com www.alternatorparts.com/cs130_sbpage1.htm

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11-Sept-01, The day the world as we knew it ended.

[This message has been edited by theogre (edited 05-08-2002).]

quote Originally posted by theogre: Anyone else trying this... 88 GT is listed as using only a 100 amp alternator at ACDelco.com. PartsAmerica.com lists 85, 100 and 105 amp units.

Interesting info Ogre, thanks... I have been getting 94 amp alternators from every parts place I ask for them, so something is out of whack somewhere in the system.

I would do this all over again even if it were for nothing other than to install the shorter belt and to get the textured pulley.

Dave

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- Silver '88 GT 5-speed (1 of 139) w/cammed 3.4
- Black '88 GT 5-speed ZZ430TPI at Archie's
- '87 & '98 Corvette Coupes

To the best of my knowledge... Externally all CS130 are the same except clock position and the one mounting ear. Internally there are a few differances but nothing that should matter to Fiero.

The folks in the link above make kits to convert CS130 to 140 amp peak. I think you can order complete alts as well. There are a few people with similar products.

Also keep in mind.... when people are talking about alt output, they are nearly always talking Peak output. The maximum oe CS130 peak is 105 amps but durring most driving it's probably producing more like 60-70 amps of output. (If you have an underdrive pulley would be lower yet.) Your 94 was probably running around 50 in normal driving.

If you look at the full specs, you'd see peak and then another lower number at 1600RPM. That's alt shaft RPM not engine RPM. (1600 is a hair under 2x most engine's idle speed. the exact numbers would depend on the crank and alt pulleys.)

I have an article on this comming... It's been sitting around awhile but since we've had a couple questions recently I'm finishing it up... should be up soon.

quote Originally posted by theogre: Also keep in mind.... when people are talking about alt output, they are nearly always talking Peak output. The maximum oe CS130 peak is 105 amps but durring most driving it's probably producing more like 60-70 amps of output. (If you have an underdrive pulley would be lower yet.) Your 94 was probably running around 50 in normal driving.

Yeah I know this, but I have a beefy power amp driving a big subwoofer, and that extra peak output doesn't hurt one bit.

quote Originally posted by theogre: PS... my info shows only the 88's V6 had the CS series. 87 V6 still had the old SI. 87 and 88 L4 got the CS. All the other L4 got SI. As noted above, CS isn't plug and play in the older cars. It can be done and there will be notes on that with links in the comming CS article.

Even more reason to upgrade, and even more reason to look forward to your article, Ogre. Glad I lit a fire under ya to finish it up--the CSs are a HUGE improvement over the SIs! Please post the link when you've finished it.

Dave

check out the vette forums, they eat alternators just like a fiero. Mines already done one since december. and everything in mine is stock.

The conversion from SI to a CS isn't rocket science but there are some thing to look out for... I don't have all the info on that but there are a couple good links in the article that should go up sometime over the weekend or early next week. I expect shoving 105 amp CS-130s into allot of GT's would help a number of problems.

Even if you already have a CS, you can't always switch to some of the after market options due to space constraint. For example the DIS L4 won't easily take an "Igloo" CS-130 if it will take it at all. (Igloo is an aftermarket case with fins to help cool the regulator better. The fins won't clear the L4 intake manifold.)