Alternator upgrde-3 wire - The 1947 - Present Chevrolet & GMC Truck Message Board Network

lownbad71 · 09-17-2009, 12:59 AM

I read article from Madelectric in regards to 3 wire compared to single wire. I am looking to go for the three wire set up. Just not sure which alternator to use. Have a 1971 chevy Cheyenne and I am looking for the alternator which will be capable of handling all accessories.

mclairmo · 09-17-2009, 01:03 AM

I believe all 1 wire alternators made can also be wired in with 3 wires.

Rack Man · 09-17-2009, 01:11 AM

I too would like to know which 3-wire alternator to get....I am wanting a direct fit replacement as I am using the original brackets??..,

fixit-p · 09-17-2009, 01:25 AM

Here is some 12SI listings copied from madelectrical.com...

12SI, 94 amp, at 3:00 (AC-DELCO # 321-266, Lester #7294-3)
Tell the auto parts counter person that “The alternator is for a 1984 High performance Chevy Camaro, with 5.0L (305G) engine, 94amp alternator

12SI, 94 amp, at 9:00 (AC-DELCO # 321-269, Lester #7294-9)
Tell the auto parts counter person that “The alternator is for a 1985 Buick Riviera, 5.0L (307Y engine), with Heavy Duty options and Air Conditioning.”

12SI, 94 amp, at 12:00 (AC-DELCO #none found, Lester #7294-12)
No AC DELCO part number or application was found for this output model at 12:00 position.

Andy4639 · 09-17-2009, 02:16 AM

This is the one I used.

Uses all the factory brackets and does a fare job with all the electronics in the truck.

Rack Man · 09-17-2009, 02:41 AM

Ok..I'm a bit confused still on which one to purchase...there are what seems to be hundreds of parts numbers that may or may not work....

Couple questions:

What does the 12SI stand for?...Are 10SI's no good?
What does the 3:00, 9:00 & 12:00 stand for?
Is that Camaro one listed above a direct replacement for our trucks and its bracketry?
Will the M&H wiring conversion kit plug right into the Camaro one?

Also, andy4639...the pics are great but which one did you use?...got a part number or year, make & model of what its from?

Andy4639 · 09-17-2009, 03:08 AM

Pss I'm @ work tonight... I'll look tomorrow and let you know. I'm going to say it's a camaro one for a late model 90's. The bracket's are for the 71 truck. I did the voltage regulator bypass and it works great. I'm running @ 14 to 15 volts with the A/C on.

**Green Machine** · 09-17-2009, 03:41 AM

We've done all 3 of our trucks now. We get the $15 harness and regulator plug from Classic parts of America. Then go to your favorite parts house and get an alternator for a 1978 1/2 ton pickup.

You should get a 63 amp 10SI alternator, which is almost double the amps of the old 37 amp unit. The case will look almost identical to the old with the same dimensions and usually fits just fine for around $50 rebuilt. I think we had to get a slightly longer belt for valve cover clearance because the case is all round with no cutout for the valve cover.

63 amp or so will easily handle all stock stuff and some upgrades. At some point a larger alt will require the charging wires to be upgraded to handle the current. Stay with the 3 wire, Mad Electrical does a good job of explaining why. 1 wire is simply a battery charger, 3 wire delivers full voltage to all the electrical circuts on the truck because of the voltage sensing wire checks the load voltage like it should, not just the alternator output.

rwolf9653 · 09-17-2009, 09:15 AM

Subscribed. There is some good info flying around in this post!

Longhorn Man · 09-17-2009, 09:30 AM

moved to electrical. Lotsa good info there, and in the sticky FAQ there too.

**VetteVet** · 09-17-2009, 10:02 AM

http://www.chevelles.com/techref/tecref14.html

fixit-p · 09-17-2009, 10:27 AM

The one pictured in post 5 is a 12SI @ 3:00 o clock which refers to the position of the wire connector in relation with the threaded hole (threaded hole being 12 o clock). The 12SI is rated for more amps and has better cooling by design and would be my choice.

Edit>>> The CS130 as vetteVet posted is superior to any SI series alt....I can't believe it took 25 mins on my op thats what happens when you kind of have to listen to wifey

stellar · 09-17-2009, 11:17 AM

Quote:

Originally Posted by mclairmo

I believe all 1 wire alternators made can also be wired in with 3 wires.

This quote above is not correct. There are different types of 1 wire alternators. Some can and some can't be wired with 3 wires.

Byronic · 09-17-2009, 07:19 PM

Subscribed. I need power.

Andy4639 · 09-18-2009, 02:01 AM

I have a aftermarket volt gauge in the truck and it reads over 14 volts most of the time. Depending on the load @ the time this shot was with the A/C on.

A/C off:

lownbad71 · 09-18-2009, 11:47 PM

Thanks guys. Its amazing the wealth of knowledge you can find on this site. Know that it is always appreciated.

Rack Man · 09-19-2009, 06:09 PM

I went ahead and took "Green Machine's" advice since he has done 3 conversions succesfully and I have done zero!....Napa guy agreed that 63 amps should be more than adequate for my set up!

I picked up this alternator form Napa...For a few extra bucks I chose to go for an all new unit vs. the rebuilt....I spent $80.00....It bolted up perfect....connector is at 3:00 which may not be ideal but it won't hurt anything either as there is plenty of clearance around the valve cover.

Application again is for a 1978 Chevy 1/2 ton w/350

Andy4639 · 09-19-2009, 06:41 PM

Did some looking today after fixing a golf cart on the truck alternator. Here are the numbers.

P7273-3
5210208
38011501 these were all on a label then I found these stincilled on the alternator 1101240 94A.

If you look close you can see the 94A stamped into the case.

Here is some more info I found googled it.
12SI Series Alternator for Delco
94 Amp, 12 Volt, Self Exciting
Pulley Type: 1V
Mtg. Ear Clocking: 12:00
Mtg. Ear Hole Size: M8 x 1.25
OE# 1101240,1101245,1105648
PIC# 240-300,240-301,240-308
Lester: 7294
Vehicle Application:
Buick 1984-1987 V6 3.8L

Here is another alternator I have it's a 100amp.

**Green Machine** · 09-20-2009, 08:28 AM

Great !!! Glad it worked out good for you ! I know there are bigger newer design alternators, but we just wanted the lights not to dim at idle, hold the heater fan speed and get more modern with an internal regulator but not so big as to overload the original charge wires. The 10SI case looks more correct for those years too.

ratty65 · 04-08-2013, 05:28 PM

Quote:

Originally Posted by Andy4639

Did some looking today after fixing a golf cart on the truck alternator. Here are the numbers.

P7273-3
5210208
38011501 these were all on a label then I found these stincilled on the alternator 1101240 94A.

If you look close you can see the 94A stamped into the case.

Here is some more info I found googled it.
12SI Series Alternator for Delco
94 Amp, 12 Volt, Self Exciting
Pulley Type: 1V
Mtg. Ear Clocking: 12:0
Mtg. Ear Hole Size: M8 x 1.25
OE# 1101240,1101245,1105648
PIC# 240-300,240-301,240-308
Lester: 7294
Vehicle Application:
Buick 1984-1987 V6 3.8L

Here is another alternator I have it's a 100amp.

Hate to bring up an old post but was wondering if there was any rewiring needed or was this a straight plug and play?

**VetteVet** · 04-08-2013, 11:02 PM

The top two pictures are of the 12 SI alternator and the bottom two are of the CS 130.
They are wired different in the conversion from the stock 10 SI externally regulated unit, but it is not difficult .

Here is a thread that may help. It is rather long so don't get bored.

...........http://67-72chevytrucks.com/vboard/s...d.php?t=567472

09-17-2009, 12:59 AM	#1
lownbad71 Registered User Join Date: Oct 2007 Location: folsom Posts: 19	Alternator upgrde-3 wire I read article from Madelectric in regards to 3 wire compared to single wire. I am looking to go for the three wire set up. Just not sure which alternator to use. Have a 1971 chevy Cheyenne and I am looking for the alternator which will be capable of handling all accessories.

09-17-2009, 01:03 AM	#2
mclairmo Registered User Join Date: Jan 2006 Location: Take Off Posts: 1,908	Re: Alternator upgrde-3 wire I believe all 1 wire alternators made can also be wired in with 3 wires.

09-17-2009, 01:11 AM	#3
Rack Man Registered User Join Date: Sep 2008 Location: Tempe, AZ Posts: 770	Re: Alternator upgrde-3 wire I too would like to know which 3-wire alternator to get....I am wanting a direct fit replacement as I am using the original brackets??.., __________________ My Build Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=309288

09-17-2009, 02:16 AM	#5
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,936	Re: Alternator upgrde-3 wire This is the one I used. Uses all the factory brackets and does a fare job with all the electronics in the truck. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

09-17-2009, 02:41 AM	#6
Rack Man Registered User Join Date: Sep 2008 Location: Tempe, AZ Posts: 770	Re: Alternator upgrde-3 wire Ok..I'm a bit confused still on which one to purchase...there are what seems to be hundreds of parts numbers that may or may not work.... Couple questions: What does the 12SI stand for?...Are 10SI's no good? What does the 3:00, 9:00 & 12:00 stand for? Is that Camaro one listed above a direct replacement for our trucks and its bracketry? Will the M&H wiring conversion kit plug right into the Camaro one? Also, andy4639...the pics are great but which one did you use?...got a part number or year, make & model of what its from? __________________ My Build Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=309288 Last edited by Rack Man; 09-17-2009 at 02:44 AM.

09-17-2009, 03:08 AM	#7
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,936	Re: Alternator upgrde-3 wire Pss I'm @ work tonight... I'll look tomorrow and let you know. I'm going to say it's a camaro one for a late model 90's. The bracket's are for the 71 truck. I did the voltage regulator bypass and it works great. I'm running @ 14 to 15 volts with the A/C on. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

09-17-2009, 03:41 AM	#8
Green Machine Senior Member Join Date: Jul 2004 Location: Estherville, Iowa Posts: 3,371	Re: Alternator upgrde-3 wire We've done all 3 of our trucks now. We get the $15 harness and regulator plug from Classic parts of America. Then go to your favorite parts house and get an alternator for a 1978 1/2 ton pickup. You should get a 63 amp 10SI alternator, which is almost double the amps of the old 37 amp unit. The case will look almost identical to the old with the same dimensions and usually fits just fine for around $50 rebuilt. I think we had to get a slightly longer belt for valve cover clearance because the case is all round with no cutout for the valve cover. 63 amp or so will easily handle all stock stuff and some upgrades. At some point a larger alt will require the charging wires to be upgraded to handle the current. Stay with the 3 wire, Mad Electrical does a good job of explaining why. 1 wire is simply a battery charger, 3 wire delivers full voltage to all the electrical circuts on the truck because of the voltage sensing wire checks the load voltage like it should, not just the alternator output. __________________ 1968 C10 307 3spd Long Fleet ------ http://67-72chevytrucks.com/vboard/s...d.php?t=201103 1970 C10 305 Super T10 Long Fleet --- http://67-72chevytrucks.com/vboard/s...d.php?t=202285 1971 C20 383 TH350 Dana Posi ----- http://67-72chevytrucks.com/vboard/s...d.php?t=206894 2001 GMC Sierra 1500 C3 6.0 Last edited by Green Machine; 09-17-2009 at 03:57 AM.

09-17-2009, 09:15 AM	#9
rwolf9653 more ideas than money Join Date: Dec 2008 Location: spring grove, pa Posts: 1,068	Re: Alternator upgrde-3 wire Subscribed. There is some good info flying around in this post! __________________ Randy 1948 Chevy 3100 5 window 1966 Chevy C30 Dually 1967 Chevy K10 1972 Chevy K20 1972 Chevy C10 1972 Chevy K5 Blazer 1987 Chevy V10 2003 Chevy Suburban

09-17-2009, 09:30 AM	#10
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: Alternator upgrde-3 wire moved to electrical. Lotsa good info there, and in the sticky FAQ there too.

09-17-2009, 10:02 AM	#11
VetteVet Msgt USAF Ret Join Date: Jan 2005 Location: Kalamazoo, Michigan Posts: 8,707	Re: Alternator upgrde-3 wire http://www.chevelles.com/techref/tecref14.html __________________ VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative.

09-17-2009, 07:19 PM	#14
Byronic The Beach Cruiser Join Date: May 2009 Location: Panama City, Florida Posts: 358	Re: Alternator upgrde-3 wire Subscribed. I need power. __________________ 1999 Silverado DD 1966 Panel Truck 2003 Harley Road Glide 1967 Schwinn Tandem Single Speed

09-18-2009, 02:01 AM	#15
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,936	Re: Alternator upgrde-3 wire I have a aftermarket volt gauge in the truck and it reads over 14 volts most of the time. Depending on the load @ the time this shot was with the A/C on. A/C off: __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

09-18-2009, 11:47 PM	#16
lownbad71 Registered User Join Date: Oct 2007 Location: folsom Posts: 19	Re: Alternator upgrde-3 wire Thanks guys. Its amazing the wealth of knowledge you can find on this site. Know that it is always appreciated.

09-19-2009, 06:09 PM	#17
Rack Man Registered User Join Date: Sep 2008 Location: Tempe, AZ Posts: 770	Re: Alternator upgrde-3 wire I went ahead and took "Green Machine's" advice since he has done 3 conversions succesfully and I have done zero!....Napa guy agreed that 63 amps should be more than adequate for my set up! I picked up this alternator form Napa...For a few extra bucks I chose to go for an all new unit vs. the rebuilt....I spent $80.00....It bolted up perfect....connector is at 3:00 which may not be ideal but it won't hurt anything either as there is plenty of clearance around the valve cover. Application again is for a 1978 Chevy 1/2 ton w/350 __________________ My Build Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=309288 Last edited by Rack Man; 09-19-2009 at 06:11 PM.

09-19-2009, 06:41 PM	#18
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,936	Re: Alternator upgrde-3 wire Did some looking today after fixing a golf cart on the truck alternator. Here are the numbers. P7273-3 5210208 38011501 these were all on a label then I found these stincilled on the alternator 1101240 94A. If you look close you can see the 94A stamped into the case. Here is some more info I found googled it. 12SI Series Alternator for Delco 94 Amp, 12 Volt, Self Exciting Pulley Type: 1V Mtg. Ear Clocking: 12:00 Mtg. Ear Hole Size: M8 x 1.25 OE# 1101240,1101245,1105648 PIC# 240-300,240-301,240-308 Lester: 7294 Vehicle Application: Buick 1984-1987 V6 3.8L Here is another alternator I have it's a 100amp. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.



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09-20-2009, 08:28 AM	#19
Green Machine Senior Member Join Date: Jul 2004 Location: Estherville, Iowa Posts: 3,371	Re: Alternator upgrde-3 wire Great !!! Glad it worked out good for you ! I know there are bigger newer design alternators, but we just wanted the lights not to dim at idle, hold the heater fan speed and get more modern with an internal regulator but not so big as to overload the original charge wires. The 10SI case looks more correct for those years too. __________________ 1968 C10 307 3spd Long Fleet ------ http://67-72chevytrucks.com/vboard/s...d.php?t=201103 1970 C10 305 Super T10 Long Fleet --- http://67-72chevytrucks.com/vboard/s...d.php?t=202285 1971 C20 383 TH350 Dana Posi ----- http://67-72chevytrucks.com/vboard/s...d.php?t=206894 2001 GMC Sierra 1500 C3 6.0

04-08-2013, 11:02 PM	#21
VetteVet Msgt USAF Ret Join Date: Jan 2005 Location: Kalamazoo, Michigan Posts: 8,707	Re: Alternator upgrde-3 wire The top two pictures are of the 12 SI alternator and the bottom two are of the CS 130. They are wired different in the conversion from the stock 10 SI externally regulated unit, but it is not difficult . Here is a thread that may help. It is rather long so don't get bored. ...........http://67-72chevytrucks.com/vboard/s...d.php?t=567472 __________________ VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative.

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