Alternative Alternators

I'm wondering what later model GM vehicles can be alternator donors for a '70 GS. I will rewire to install an internally regulated, higher amp alternator.

What really matters to make the swap from a physical sense is whether the alternator body will fit in the 455 alternator bracket and if the "clock" position of the wiring locations is correct.

Please provide your input and experience. Thank you.

 

Both of these issues are valid. From a size standpoint, the two are the same diameter. The 12SI is the one with the plastic fan. If you intend to upgrade to a higher output, I suggest that this is the way to go. If, you do not, you may run into temperature problems as the airflow through the unit is a problems due to the heat generated by the higher output. Is there a good reason for the upgrade? A higher electrical load is a good one, however, just building to numbers is a lesser reason. Ray

 

Thanks Ray.

The upgrade (not an over the top one though) is due to new and planned power issues. Currently running MSD, high power stereo amp, electric fans. Will put A/C on this car in the future. So a little more alternator is becoming a neccesity if I sit in a traffic jam with the stereo and A/C on.

So if I buy a new 12si or 10si from what vehicle type should I specify at the counter? I really don't want to buy a new unit only to open it up for a re-clock - would probably void the warranty.

 

I bought mine for a 76 Electra with power everything.........p Worked for me:TU:

 

Consider going a bit newer than the 12si, take a look at a CS130 configured for 1 wire operation, clean install plenty of power (typically 120-150 amp) and it makes more power at a lower rpm than the 12si.
Check in the vendor section for Jamie, he goes by 65GSConvert or something like that.
I'm running CS-130 and it works very well.

 

Before considering the concept of one-wire operation, consider why GM did not use this concept. It works for charging the battery, but can lead to dim lights, weak spark,etc. The CS130, is expensive and requires different mounting than the 12SI. The application will require knowing the output you need. It sounds to me like at least 78 is necessary, but the 12SI goes to 94 amps. I suggest the 94 amp unit; it will likely allow for additional electrical loads as well. I'll check my literature. How do you want it clocked? If looking at the rear of the unit, the small mounting tang is 12o'clock. One bolt hole to the counterclockwise direction would be nine o'clock position. How is your alternator presently clocked? Do you want to duplicate this insatallation? Ray

 

My CS130 was a bolt in, on my original mounts, cost $100 shipped. My headlights are on relays so I don't have any problem with that.

 

1 wire cs-130 is the way to go

i can buid a 1 wire 140 amp(last one was 153)cs-130,bolts right in,same size.no fuss, no muss.(what the heck does that mean?)$155.00 + $15.00 shipping.can add chrome package for another $60.00.there is NO drawback to the 1 wire other than it wont drive the indicator light.i supply the plug to power the light however,only on the 72 & up models.the charge path is thru the batt cables not the plug.the one wire is used commonly on ag equipment,marine and heavy machinery.on the 10-12 si units if you go one wire you may have to rev it up to exite the reg on a hi-output.not on the cs-130 since they were designed for hi-output at low rpm to get the batt back up quick to power the computer efficently,and most late cars have butt-loads of power robbing needless options.:laugh:

 

Yes the CS130 or CS144 would both be great alternators. For this application it would be good to increase the output wire from the present 10 gage to 8 gage and wire directly to the battery or to the battery post on the starter solenoid.

The alternator on the 70 GS is wired with 10 gage wire with a fusible link between the harness and the battery terminal on the starter solenoid. This will be a high resistance point.

This duplicates how the output from the 120 amp CS144 alternator on a Turbo Regal is wired into the car.

I made this change while getting rid of the resistance wire that originally fed the points controlled coil, with a 12 gage wire to feed a blaster coil controlled by an MSD distributor.

 

I replaced the 10 ga with 6ga.

 

I repeat the original post. If GM saw no drawbacks, they would have used the 1 wire set up. Since they wanted remote sensing of voltages, they used a 3 wire. Simple is not always best. Try it yourself. Ray

 

How about on a 350?

Interesting topic!

How about on a '71 350? I've got the standard 3-wire, remote regulator, 63amp (I think) alternator, it's bearings are starting to go.

Which later alternator would drop in, and give me more charging at lower rpm, with the least "fuss and muss" (yup, whatever that means)?

 

I swapped in my 79 G-body (GN, Regal, Century, Cutlass, Malibu) alternator and it fit in fine! It's internally regulated but easily connected, well worth it for the 120 amp version.

 

I still have the question of the alternator's clocking. When viewed from the rear, where is the connector in relation to the small mounting ear? I recommend the 12SI, 94 amp application. The 12SI delivers more current for high draw devices, and with its modified windings, charges slightly harder at idle. Mine shows a full 15 volts @500rpm, even with the A/C on. The voltage drops slightly with the blower on high, but still stays above 14 volts. Having the alternator's clocking perference will allow me to provide an application with the correct charging rate and connector location. It would then be a matter of specifying, for example, an '85 Olds 98 w/307 Y engine. The 12SI will bolt into your present 10DN application and provide internal regulation. Ray

 

Yup, clocking info might help...

My plug goes in at the 3:00 o'clock position, when looking at it from the back with the small mounting ear at 12 o'clock.

I understand the 12SI is internally regulated, but is NOT a 1-wire alternator?

How do I wire around my firewall-mounted regulator, and will my indicator light still work?

Thanks for the Help!

 

Here's some good links:

The "madelectrical link" provides a quick reference chart for various 10 & 12 si models in relationship to clock positions and the associated part numbers.

http://www.madelectrical.com/electricaltech/delcoremy.shtml

http://207.158.252.111/gw/alt/edge_Alternator_Theory.html


John

 

Actually, the conversion is surprisingly simple. Your alternator, regardless of whether it is an externally or internally regulated unit, has three wires. On the 10DN or externally regulated unit, the three wires are battery, field, and regulator. On the internally regulated units, the three wires are battery, sense and alternator light. The battery wire, the big red one stays on the large screw down connection on the new alternator. The F wire on the externally regulated unit will become your sense wire, and will connect to the big battery lead. The other end will connect to the #2 connection on the 12SI. Here is the neat part. If you connect the brown wire on the externally regulated regulator to the #1 wire connection on the alternator, you are finished. The other wiring is now extra, and can be removed. In many cases, the regulator goes to the firewall, on the opposite side of the alternator mounting. This may require some additional wire, but careful routing will solve that issue. Another option is to use the original regulator wiring, connecting the brown #4 connection to the #2. Then connect the blue wire on the alternator end to the #1. This will simplify the wiring, but will require the removal of the external regulator to prevent inadverdent reconnection by a dim bulb. The question now is whether you want to use the 78 or 94 AMP alternator, and clocking. On my next posting, I will address the issue of the 3 o'clock clocking previously posted. I will answer any questions people may have regarding this issue. I am experienced in these conversions, and would rather answer questions than put out fires. Ray

 

How much different is having the sense wire terminal directly connected to the output terminal of an three wire alternator compared to a single wire alternator. Almost all 1971 through 1987 GM 10SI or 12SI alternator equipped cars were wired with these two connections having a short jumper wire.

REMOTE VOLTAGE-SENSING IS THE KEY TO GOOD ELECTRICAL SYSTEM PERFORMANCE

If the sense wire was wired remotely as shown in the Mad Electrical argument, this might be a valid point. In reality this is never the case. With an adequately sized output wire it is perhaps a moot point.

 

The biggest concern is for electrical drops. Poor connections can lead to its share of problems. The original GM hook up allows for quick "spool up" of tha alternator. If using the three wire, the low battery voltage to the alternator tells the alternator to charge immediately, rather than doing it alfer coming up above 1500 rpm. The one wire regulator is also different in configuration than the original three wire, making replacement somewhat of a hassle. Ray

 

I'm Done!

Yep. Finished. This was easy.

If you go with the 12si (like I did) you want the 7294-3. The clocking at 3 totally exposes the connections AND the heat sink. Here is a great website to explain some things about these alternators.

http://www.madelectrical.com/electricaltech/delcoremy.shtml


My total cost was about $85 for a lifetime warranty reman alternator, a pigtail, terminals, and some 8 and 14 guage wire.

I bypassed the original charge wire (since its a pain in the neck to yank from the harness) and went straight to the battery.

IMO - don't bother with the one-wire setup cuz the three-wire is a milk-run and you get a truly operational system with idiot light and sensing.

Brad.