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GameboyRMH
GameboyRMH MegaDork
6/24/14 9:43 a.m.

Anyone know what cars use an 85 amp or greater CS121 alternator with the mounts 180 degrees apart and a V-belt pulley?

As in, looks like this:

Trying to find one to do an alternator swap on my sammy. I know you guys can get these at literally any parts store, but American cars aren't too common around here.

Bumboclaat
Bumboclaat HalfDork
6/24/14 10:00 a.m.

If you can figure out just one model that uses it, you can then use rock auto's reverse lookup (click on the part number of a particular part) for a list of models that use the same part.

GameboyRMH
GameboyRMH MegaDork
6/24/14 10:08 a.m.

Whoa think I found my answer here:

http://www.summitracing.com/parts/tff-7937a/applications

Just gotta see if there's something more powerful, over 100A would be ideal.

Edit: Found it:

http://www.summitracing.com/int/parts/pwm-8462/applications

1988RedT2
1988RedT2 PowerDork
6/24/14 10:08 a.m.

There's a fair bit of info here: http://www.alternatorkit.com/

I used their kit when I rebuilt the alt for our '66 Nova.

Edit: Never mind. It looks like you've got some kind of newfangled alt. These would be from GM cars of the "Golden Era" of the American automobile.

novaderrik
novaderrik PowerDork
6/24/14 1:11 p.m.

1990ish Pontiac Grand Am with the 2.5 was the donor for the one i put in my Nova way back when.. i've got one from a 2.8 powered late 80's fwd Grand Prix in my T Type- it's got offset mounting ears, but i fixed that with a really simple adapter made out of a piece of 1/8" steel with two holes drilled in it that allows me to use it in brackets designed for an alternator with straight across mounts:

stuart in mn
stuart in mn PowerDork
6/24/14 1:18 p.m.

What do you need a 100 amp alternator for?

DaveEstey
DaveEstey UberDork
6/24/14 1:18 p.m.

Not GM, but FC RX7 does:

Hungary Bill
Hungary Bill Dork
6/24/14 1:19 p.m.

I believe the Oldsmobile Firenza from the 1985-ish period (vin code K. With AC) is 105 amps.

It's not a v-belt but the guys at auto-zone have an electric impact wrench behind the counter so they can "zap" off the pulley for an easy swap. Not sure if it's 180-off mounts though. I adapted one for use in my Toyota 4x4.

I have one that's gathering dust. if you want it just pay shipping.

GameboyRMH
GameboyRMH MegaDork
6/24/14 1:20 p.m.
stuart in mn wrote: What do you need a 100 amp alternator for?

Headlights with the power of a thousand suns, fog lights, maybe a winch later. Sponsor's paying for it.

GameboyRMH
GameboyRMH MegaDork
6/24/14 1:21 p.m.
Hungary Bill wrote: I have one that's gathering dust. if you want it just pay shipping.

Wish I could, but I need it by this weekend (and I have to get a mount fabbed!). I found a place that has a bunch of CS121s that I'm going to check after work.

Hungary Bill
Hungary Bill Dork
6/24/14 1:28 p.m.
stuart in mn wrote: What do you need a 100 amp alternator for?

What DON'T you need a 100 amp Alternator for?

GameboyRMH
GameboyRMH MegaDork
6/24/14 1:31 p.m.

Some think you can never have too many alternators!

This was for a truck with a high-powered radio transmitter in it.

This was for a truck that powers some kind of industrial pump.

GameboyRMH
GameboyRMH MegaDork
6/24/14 1:44 p.m.

Hey 'nother question...I notice all of these have a fan, some a more traditional fan with crudely bent blades and some with a fan using vanes on a disc like what you'd see in a vacuum cleaner or hovercraft lift engine. Will these survive hitting water at high revs?

stuart in mn
stuart in mn PowerDork
6/24/14 1:58 p.m.
Hungary Bill wrote: What DON'T you need a 100 amp Alternator for?

In most cases an alternator that big just isn't necessary, so it's a waste of money.

jstand
jstand Reader
6/24/14 2:58 p.m.

Depending on the donor, you may be able to remove the housing bolts and rotate the front and rear housings to 180 degrees and reinstall the bolts.

Hungary Bill
Hungary Bill Dork
6/24/14 3:01 p.m.
GameboyRMH wrote: Hey 'nother question...I notice all of these have a fan, some a more traditional fan with crudely bent blades and some with a fan using vanes on a disc like what you'd see in a vacuum cleaner or hovercraft lift engine. Will these survive hitting water at high revs?

I don't know the answer, but I like where this is headed.

Mr_Clutch42
Mr_Clutch42 HalfDork
6/24/14 3:05 p.m.

In reply to stuart in mn: Isn't the standard amp ratings for alternators from 80-100 amps?

Hungary Bill
Hungary Bill Dork
6/24/14 3:16 p.m.

Depends on the Vehicle, I would imagine. I believe my Toyota, and I know my Impala, both had a rating of about 45-amps (both carbureted). 1st Gen RX-7 was near 55-amps (carbureted) and the 2nd gen RX-7 had somewhere near 80-amps (injected).

In the case of swapping the 100-amp in my Toyota: the cost for either the GM alternator or the Toyota alternator was about the same, so I figured "why not?" GM parts are easier to come by in Texas.

GameboyRMH
GameboyRMH MegaDork
6/25/14 8:11 a.m.

OK so I checked the biggest alternator rebuild shop here and my best bet for finding GM alternators by far, he only had one CS121 with the 180deg mounts and no V-belt pulleys that could go on it. I was about to leave and then the guy came out and took a look at my engine and based on what I wanted to do, had an idea. He said a Mazda BH alternator with a V-belt pulley put on it should be a direct bolt-on swap (aside from customizing the electrical connectors). It's only 65A though, so it'll get the job done with the lights but not much more. Saving the fab work would be a big help on this tight schedule though.

I took some measurements and it looks like it should indeed be a direct bolt-on swap. I'm gonna pick it up this evening.

G13A alternator:

Mazda BH alternator:

This will be a big innovation in Samurai modification if it works.

Edit: Just confirmed from specs that the 66mm distance inside the lower mount is identical, trying to confirm the top-to-bottom mount span now.

16vCorey
16vCorey PowerDork
6/25/14 1:20 p.m.

'86-'93 Buick Century or Olds Cutlass Ciera with a 3.3L or 3.8L engine is what you're looking for, available in 85, 100, or 105 amp flavor. They all have serp belt pulleys, but almost literally any GM V belt pulley ever made will fit it.

Hungary Bill
Hungary Bill Dork
6/25/14 1:49 p.m.

Can you take the V-belt pulley off of your current alternator and swap?

GameboyRMH
GameboyRMH MegaDork
6/25/14 2:31 p.m.
Hungary Bill wrote: Can you take the V-belt pulley off of your current alternator and swap?

Only with some machining, the shaft diameter is different.

I'm trying some PIAA Xtreme White Plus bulbs that use factory power levels, if these are good enough that will save some of the need for more electricity.

81cpcamaro
81cpcamaro HalfDork
6/25/14 3:00 p.m.

The v-belt pulley from older GM alternators will fit on the newer ones no problem. Also, the 100 amp alternator from my 92 454 (probably the same for 91-95 models) has the same dimensions as you listed in the original post, just another possible one.

T.J.
T.J. PowerDork
6/25/14 3:44 p.m.

I installed an AC Delco CS130 internally regulated alternator on my Mini about 5 or 6 years ago. I had to reclock it so that mounting holes lined up how I needed them. I have essentially no electrical accessories on the car other than lights, horn, ignition, and an electronic rev limiter. Do I ever need 100 Amps out of the alternator? Nope. Is it nice to not see my head lights dim to uselessness at idle? Yep. I also got to ditch the Lucas external regulator box. I liked it so much, I also fit a similar alternator in my BMW 2002 megasquirt project.

GameboyRMH
GameboyRMH MegaDork
6/27/14 7:58 a.m.

OK well it turns out the Mazda BH alternator is just as much work to swap in as the GM alternator. It uses a bigger bolt on the lower mount, and the span between the mounts on the two sides is about 1.5cm longer.

Should be easier to find local replacements at least. The new PIAA bulbs work as advertised and saved some power and the trouble of a wiring upgrade there. I'm gonna try to run a pair of 55W fogs on the stock alternator for this weekend, it may or may not work.

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