Alternator Tech

Extreme 4 Wheelin' - Tech
GM Alternator Info.

The most common charging system upgrade/modification is adding or converting to a GM style internally regulated alternator produced by AC-Delco. The most common varieties are listed in TABLE 1.

Some of the main advantages are easy availability, plus common mounting and wiring. There are some slight variations of both, but this table lists models from each series that are mostly interchangeable (common 6.6" 180 degree mounts, overall case sizes will vary). SI units shown are standard 3-wire hookup, CS units require plug adapters.

TABLE 1 - ALTERNATORS
(Common Mounting)

Series	Example Vehicle (V groove pulley)	Lester Numbers	Amps	~ Reman Price (core)
10SI	78 Cutlass Supreme V8-260	7127 (63A)	40-63	$35 (10)
12SI	83 Chevy Cavalier 2.0L 86/87 Buick Regal V8-307 (metric threads)	7271,7272,7273 (78A) 7294 (94A)	78-94	$65 (30) $100 (25)
15SI	81/83 Chevy Camero 5.0L	7134(105A)	70 -105	$60 (30)
17SI	86-90 Chev, GMC, P series van 6.2L	7287 (120A)	108 - 120
CS130	88/89 Pontiac Firebird 5.0L (no pulley) 88 Chevy Caprice 5.0L (1V)	7061 7808, 7888	100 - 105	$70 (45) $70 (30)
CS144	93 Caddy RWD, 5.7L V8 (serp pulley)	8112 (140A)	124-145	$120 (70)

By far the most common alternator ever produced is the 10SI ("System Integrated"), with the 12SI being an upgraded version by means of better cooling (noted by a plastic fan) to handle higher current outputs. The 15SI and 17SI are physically larger units, but still share the basic 6.6" mounting center to center that was used back to the 10SI (and before).

SI series connector wiring pin-out:

1 = Small gauge wire that comes from the idiot light and energizes the alternator.
2 = Heavy gauge wire to the battery supply (loop back to post on back of alternator).

The infamous '1 wire' alternator is based on the 10SI or 12SI units and require only the #2 terminal (sense) line to be connected to the output post. These units detect the rotation of the alternator to turn the field on, therefore don't require the switched power on the #1 terminal. Typically these are used on implement applications, or have had aftermarket regulators installed. Generally, you are better off staying with the more common '3 wire' units.

Latest series to be introduced is the CS ("Charging System") 130 or 144 (for 130mm or 144mm stator). The CS130 has a lower max output than the 15/17SI, but better low speed output with less noise. However, I have read that the CS130 is not all that strong, and does have reliability problems. Specifically, with cracked back cases related to belt loading. CS130's are slightly smaller than the 10SI, but MOST (there are exceptions) use the same 180 degree 6.6" mounting.

CS144 is the size of a 15/17SI with an impressive 124-145 Amp output capacity. These are the current 'beast' alternators available on the latest high demand vehicles. Like the CS130's, there are some models with different mounting pattern from the SI norm. I am not aware of any available units using a single 'V' groove pulley. However, pulleys are interchangeable from 10SI thru CS144 (fans are NOT).

CS series wiring pin-out:

S = Heavy gauge wire to the battery supply (loop back to post on back of alternator).
F = not used.
L = Small gauge wire that comes from the idiot light and energizes the alternator.
P = not used.

The following adapters are available to go from SI wiring to a CS alternator:

AC Delco: 8077
Haywire: 2110
Painless Wiring: 30707

The switched 'light' (terminal 1 on SI or 'L' on CS), must have 12V switched power with between 35 and 350 ohm resistance (typically the light itself). If below 35 ohm, the CS units will fail. I have read that switched power (no resistor) can be connected to the 'F' terminal instead, where there is supposed to be an internal resistor. I've not confirmed this, so be ware.

Delco 10SI Series
61 Amp, 12 Volt, CW, 1-Groove Pulley
Used On:
(1985-73) Buick, Cadillac, Chevrolet, GMC, Oldsmobile, Pontiac 4, 6, 8 Cyl
Replaces:
Delco 1105360
Lester Nos:
7127, 7128, 7282

Delco 12SI Series
78 Amp, 12 Volt, CW, 1-Groove Pulley
Used On:
(1989-83) Buick, Cadillac, Chevrolet, GMC, Oldsmobile, Pontiac 4, 6, 8 Cyl.
Replaces:
Delco 1100250, 1105370, 1105372 & others
Lester Nos:
7271, 7272, 7272R, 7273
Dimensions:
M8 x 1.25 Threaded Adj. Ear

Delco 12SI Series
94 Amp, 12 Volt, CW, 1-Groove Pulley
Used On:
(1987-84) Buick, Cadillac, Chevrolet, GMC, Oldsmobile, Pontiac 4, 6, 8 Cyl.
Replaces:
Delco 1101308
Lester Nos:
7294
Dimensions:
M8 x 1.25 Threaded Adj. Ear

Delco CS130 Series
100-105 Amp, 12 Volt, CW, 1-Groove Pulley
Used On:
(1990-88) Buick Estate Wagon 5.0L
(1990-88) Cadillac Fleetwood Brougham (RWD) 5.0L
(1990-88) Chevrolet Caprice 5.0L
(1990-88) Oldsmobile Custom Cruiser 5.0L
(1989-88) Pontiac Safari Wagon 5.0L
Replaces:
Delco 1101229, 1101275, 1101292
Lester Nos:
7808, 7888

Delco CS144 Series
140 Amp, 12 Volt, CW, 6-Groove Pulley
Used On:
(1996-94) Buick Roadmaster 5.7L
(1996-93) Cadillac Fleetwood Brougham (RWD) 5.7L
(1996-93) Chevrolet Caprice 4.3L, 5.7L
(1996-95) Chevrolet Impala 5.7L
(1995-92) Chevrolet Lumina APV Van 3.8L
(1995-92) Oldsmobile Silhouette 3.8L
(1995-92) Pontiac Trans Sport 3.8L
Replaces:
Delco 10479891, 10480201
Lester Nos:
8112

Helpful Alternator Links

General alternator info: http://www.4alterstart.com/alternators/

Find out what a vehicle model had: http://www.olyonline.com/PPR%20Application.pdf

Cross Reference various alternator numbers: http://web2.wai-wetherill.com/new/crossref.cfm

How to tell a 10SI from a 12SI and more: http://www.madelectrical.com/electricaltech/delcoremy.shtml