Stock Alternator rebuild

zapp240

Active Member
#1
Have a local shop that will rebuild my stock original (1101 349 120A) alternator. ran the car with lights on and the defroster and the pulsing was crazy so want to refurb it but keep the case as it date matches the car. They offer a 160 or 180 amp upgrade at a significant increase in price. I Have a larger fuel pump and normal adds ons but do not have any radio upgrades. I could see if I was running some larger amps, but I do not.Is the 120 amp good enough or would it be worth the money to increase the output? Ideas?
 

Nick Micale

Tech Advisor
Staff member
#3
Just my opinion, but the alt is there to charge the battery, and unless you have a HD sound system, 120 amps works fine.

These cars "eat" alternators, especially if it is subjected to high RPM's in a performance build, they do not last very long. My race car kills one a year!

If you have "pulses" in the electrical system, there may be some bad grounds?

I have a couple spare alts, one from O'Rielly, and the other from Autozone, and both have lifetime warranties.

Considering that lights and dash stuff use body grounds both in the cabin and under the hood, that could be part of your issue?
 
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zapp240

Active Member
#4
thanks Nick, I can go back and check some grounds but think the alt that is on the car is the original 30 year old one, so think it is time for a fresh up. i was thinking the same, since i am not running a sound system, I think the 120 A should work out.
 
#5
The auto parts option is the cheapest way out. I have done that for a long time but about a month ago I started thinking about everything I’ve changed on the car that runs on electric. Dual fans, trans cooler fan, dual dw 300 pumps and a sound system. My original alternator died on my low mileage car so I bought a 250 amp alternator. I don’t think I need 250 amps but I liked that it is capable of providing 120 amps at idle. The new alternator provides 14.5 volts at all times. I have noticed that the car runs cooler in traffic, the ac fan blows a lot more air, the windows go up much faster and I had to turn my fuel pressure down because it went up 5 psi at idle and I’m going to have to retune it because when the second pump comes on it’s too rich with the new alternator. Most of this is probably because my old alternator was on its way out I assume but I’ve looked at my voltage in my power logger logs and didn’t have low voltage until the alternator died. I am glad I spent the extra money on the alternator at this point. I have a lot of money in the car but never could bring myself to spend $310 for a alternator. Im not sure how long it will last as Nick said the auto parts store units are good for about a year if you drive these cars hard. It only has a year warranty.


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zapp240

Active Member
#6
Thanks Scott, I bought the AZ one online (the lowest priced of the 3 at 98 bucks plus 15$ core), will Install and see how the car acts, if it still pulses the headlights and such, will track down the grounding culprit, and If it does fix it, am going to send my original out and have it rebuilt and reinstall it. I like that it has all the original stamping's and then will have a backup on the shelf if the unit craps out in the future.
 

Ttype6

Well-Known Member
#7
Thanks Scott, I bought the AZ one online (the lowest priced of the 3 at 98 bucks plus 15$ core), will Install and see how the car acts, if it still pulses the headlights and such, will track down the grounding culprit, and If it does fix it, am going to send my original out and have it rebuilt and reinstall it. I like that it has all the original stamping's and then will have a backup on the shelf if the unit craps out in the future.
There is a capacitor inside the factory generator that is used to filter the AC current from leaking over to the DC side. When it gets weak,it allows AC current to go places it shouldn't be. This is the only thing that I know of that causes the flickering/pulsing. Replace it with a new one and the output voltage will be steady.
 

TurboWh1

Active Member
#9
The problem with the stock alternator is the circuitry that activates the system. The dash idiot light engages the charging system but also shorts out frequently and blows the regulator. It absolutely sucks! After my 5th alternator in the mid 2000s it was time to ditch the factory wiring. You can make your own just do some research on the cs style regulator. 120a is fine. Voltage is want you need to make the entire system happy. Same alternator on my car for 13 years now. 20k miles and countless 10-11 second passes.
 
#10
The right way to do it is to add up all of your current draws in the electrical system and that will tell you how large of an alternator that you need, bigger injectors, larger fuel pump etc.etc. then you'll truly know what amp alt. That you'll need
 

turbobitt

Well-Known Member
#11
The right way to do it is to add up all of your current draws in the electrical system and that will tell you how large of an alternator that you need, bigger injectors, larger fuel pump etc.etc. then you'll truly know what amp alt. That you'll need
I disagree because if you did that you would have a an alternator that would charge adequately at RPM and suck charging at idle and end up with voltage dropping off and another tech post on “why is my car not charging at idle”.
The larger the rated charging capacity, typically it will charge more at idle rpm.
With these Turbo Buick’s and all the add-on electrical components I would put the largest rated alternator within the CS144 case you could find.
AG


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#12
You might get away with doing what your saying and running a higher capacity cs 144 alternator, but if the highest capacity cs144 will only put out200 amps and I have 160 lb. Injectors dual pumps big stereo system and on and on and my system is dra wing 300 amps, which my math calculations are telling me, your cs 144 isn't going to get the job done. This is exactly how the engineers determine what size alt. They need for the vehicles they are building. Why do you think the alt.amperage on all of these newer cars keeps going up its because of all of the extra electronic components ie current draws that they keep adding, no different than what we are doing with these cars by adding all of these power pulling components to our cars and as far as having a 300 amp alt. And you math tells you that all of your power (current) draws only add up to 240, it's not going to matter as the alternator will only put out whats required or demanded by the system. Now that being said I'm also not telling you to put on a 500 amp alt for a system that only draws 300 amps, just do the math and you'll be golden.
 

turbobitt

Well-Known Member
#13
You might get away with doing what your saying and running a higher capacity cs 144 alternator, but if the highest capacity cs144 will only put out200 amps and I have 160 lb. Injectors dual pumps big stereo system and on and on and my system is dra wing 300 amps, which my math calculations are telling me, your cs 144 isn't going to get the job done. This is exactly how the engineers determine what size alt. They need for the vehicles they are building. Why do you think the alt.amperage on all of these newer cars keeps going up its because of all of the extra electronic components ie current draws that they keep adding, no different than what we are doing with these cars by adding all of these power pulling components to our cars and as far as having a 300 amp alt. And you math tells you that all of your power (current) draws only add up to 240, it's not going to matter as the alternator will only put out whats required or demanded by the system. Now that being said I'm also not telling you to put on a 500 amp alt for a system that only draws 300 amps, just do the math and you'll be golden.
If using a different style alternator is an option than great, but in the end it needs to be sized over the maximum current draw with a comfortable safety factor to have satisfactory results.
AG


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