av_scott

If anyone is interested, I believe I have found the best direct fit high idle amperage replacement alternator for a vette that originally had a 10SI alternator. The advantage of this replacement alternator is that its circuit design is newer than the 10SI, 12SI and 15SI ACDelcos, provides high idle amperage and is not prone to the overheating and reliability problems associated with rewinding older units to higher amps.

Since I am running two Permacool 14" electric fans drawing 9.5amps each on my '81 vette, I found that when they turned on while idling, the headlights would dim using my original 70amp 10SI alternator. I started looking for a higher amperage alternator and originally purchased a beautiful chrome 12SI 135amp alternator from Alterstart Systems, Inc. www.4alterstart.com. I then realized the hole in the alternator for the adjusting bracket was 5/16" instead of my original 3/8" and the alternator's case was smaller and wouldn't fit the brackets. Apparently the 12SI alternator was used on '81 vettes without a rear window defroster while mine with the rear defroster unit uses a 10SI unit. After speaking with Alterstart Systems and doing my own research I realized that I didn't only need a higher amperage alternator but most importantly I needed an alternator that has a higher idle amperage output. I found this very informative article on the Idaho Corvette page: http://www.idavette.net/hib/reman.html

After searching the Internet I came across O.E. Parts H.Q. and while I was on the phone with them they added the following 120amp remanufactured ACDelco alternator to their website:

AC Delco Part # 334-2345, GM #19135903

They didn't have this alternator in stock but special ordered it for me and it arrived a couple weeks later for $85.12 along with AC Delco Part # 8078, GM#12102921 for $17.85 which is the conversion wire to plug directly into the original 10SI wiring harness. Shipping was about $20. Look at the Idaho Corvette page above to see if you may need the 8077 conversion wire depending on the resistance in the alternator's "exciter" line which is one of the wires from the alternator plug to the ignition switch.

I compared the alternator I received with my original 10SI and the brackets and holes are all in the same place with the same dimensions. The case is slightly smaller than the 10SI. All I have to do is replace the serpentine pulley with the single groove pulley. Since I am in the process of completely rebuilding my vette I haven't tried the alternator yet but I can't imagine why it shouldn't work.

If anyone has any more information regarding my findings or a better solution I would like to know about it. Also if anyone is interested in pictures of the new alternator next to the 10SI unit, just let me know.

I'm Batman

How about a link?

Sounds like a CS130 alternator. Without some modifications, they're known for self-immolation.

1970-Bronze

I've had good luck with 4Alterstart....

noonie

An old limosine trick:

They replace the pully with a smaller diameter one for long idle situations.

mrvette

'79 Sevilles with RW defroster had a thing known as a 17SI....the unit is factory rated at 108 amps.....it's what I have from AZ with lifetime warrenty....this last one seems fine after 2+ years now....maybe their rebuilder finally got it right....

av_scott

Here is a link to six pictures of the ACDelco Reman Alternator, part # 334-2345, GM # 19135903 I described in my first post alongside my original 10SI.

http://allan-scott.magix.net/

The back cover of the new alternator looks just like the back cover of the CS144 alternator shown in the picture at the bottom of the page on the link:

http://www.extreme4wheelin.com/tech/...ators/tech.htm

The link below is to an article about "SI to CS Alternator Conversion" and as you can see the picture of the CS130 alternator shows the rear cover of the alternator looking quite different to the unit I have. Also the CS130 alternator is rated at 105amps whereas the one I have is rated at 120amps as remanufactured by ACDelco. The stator diameter of the CS130 is 130mm. The original CS144 alternator was rated at 120amps and is supposed to be larger than the 10SI and the stator has a 144mm diameter. The back cover of the new alternator I have measures exactly 140mm but I don't know the diameter of the stator. The other CS121 alternator with a 121mm stator was rated at less amps than the CS130 so I don't believe it could be that either.

http://www.novaresource.org/alternator.htm

If you search at
https://www.rockauto.com/dbphp/mfr,A...412,Alternator
for part # 3342345 under ACDELCO you will find the same alternator I purchased but for $95.79 plus a $15 core charge and it describes it as 120amps.

The 15SI and 17SI units are apparently the same or larger than the 10SI so I know I don't have a rebuilt version of those.

I now believe I have some version of a CS144 but with a rear case cover diameter of only 140mm? This sounds like a good buy for the price I paid.

noonie

As you probably figured, the CS stands for charging system and the numbers stand for the od of the stator.

You may have an upgraded cs 130 or 130-D or one with an "Iceburg kit"

I'm Batman

There are multiple versions of both the CS130 and CS144 with different output levels. My Cadillac-sourced CS144 is factory-rated at 140 amps.

markdtn

That one was also used on 84-85 C4s. That is what I have too and it works fine, plugs right in to the factory harness.