63A to 100A alternator?
Thread Starter
Le Mans Master
Joined: Nov 2004
Posts: 6,128
Likes: 21
From: North Alabama
63A to 100A alternator?
Anyone who's done this conversion, I have a question. Got my new polished 100A alternator today (3 wire). Wanted to upgrade because of my Mark VIII fan. With the old 63A the battery showed 13.4v when running and the volt gauge showed about 13.1 Volts. When the fan and headlights were on, it would drop about 1.5 volts on the guage and the battery would show about 12.5v. Installed the 100A alternator and all these same checks show about 1.5v less??? Charging, Fans on/off. Lights on/off? Any ideas what is up?
Last edited by Jclgodale3; Aug 22, 2006 at 07:26 PM.
Race Director
Joined: Apr 2000
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
The new alternator might not have the same charge at idle characteristics as the old reliable 10SI alternators.
If the RPM"S drop past a certain point you are basically running off the battery. Adjust the idle up to about 1000RPM and see if that fixes it. Then go from there, maybe a new pulley to get it spinning faster at idle
If the RPM"S drop past a certain point you are basically running off the battery. Adjust the idle up to about 1000RPM and see if that fixes it. Then go from there, maybe a new pulley to get it spinning faster at idle
Thread Starter
Le Mans Master
Joined: Nov 2004
Posts: 6,128
Likes: 21
From: North Alabama
Originally Posted by MotorHead
The new alternator might not have the same charge at idle characteristics as the old reliable 10SI alternators.
If the RPM"S drop past a certain point you are basically running off the battery. Adjust the idle up to about 1000RPM and see if that fixes it. Then go from there, maybe a new pulley to get it spinning faster at idle
If the RPM"S drop past a certain point you are basically running off the battery. Adjust the idle up to about 1000RPM and see if that fixes it. Then go from there, maybe a new pulley to get it spinning faster at idle
Race Director
Joined: Apr 2000
Posts: 17,676
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Smalller pulley to make it spin faster. But sounds like you have other problems. What is the voltage across the battery at idlle without the A/C and fans on ?
Le Mans Master
Joined: Jan 2006
Posts: 9,192
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From: Boca Raton Florida
Thats not right, sounds like the regulator inside has a bug. Measure the voltage at the alternator output terminal. Idle shouls be 13+. Terminal 2 on the side is the "voltage sensing" input that tells the regulator what to do, make sure your connection there is good, although if it was bad the output should go very high with rpm.
Thread Starter
Le Mans Master
Joined: Nov 2004
Posts: 6,128
Likes: 21
From: North Alabama
Originally Posted by MotorHead
Smalller pulley to make it spin faster. But sounds like you have other problems. What is the voltage across the battery at idlle without the A/C and fans on ?
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Race Director
Joined: Apr 2000
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Made in Ch....?
Your battery should read ~12.7V by itself unconnected to the car, so you didn't connect the alternator correctly or it is toast
Your battery should read ~12.7V by itself unconnected to the car, so you didn't connect the alternator correctly or it is toast
Race Director
Joined: Nov 1999
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From: Foxfield CO 1970 Convertible
What kind of alternator did you get? i.e., is it a direct replacement for the SI style? You also might need to beef up the wiring or your wiring might be over heating and creating extra resistance.
Here's what I did when I upgraded my SI to a CS style. It's putting out about 13.9 - 14.2V at idle now.
Alternator Upgrade
Here's what I did when I upgraded my SI to a CS style. It's putting out about 13.9 - 14.2V at idle now.
Alternator Upgrade
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Originally Posted by Z-man
What kind of alternator did you get? i.e., is it a direct replacement for the SI style? You also might need to beef up the wiring or your wiring might be over heating and creating extra resistance.
Here's what I did when I upgraded my SI to a CS style. It's putting out about 13.9 - 14.2V at idle now.
Alternator Upgrade
Here's what I did when I upgraded my SI to a CS style. It's putting out about 13.9 - 14.2V at idle now.
Alternator Upgrade
I liked the Coors Light Plug...
I'm installing a serp system on my '77, that came from a 1992 Z28. I will be using a CS for sure, and had a crazy idea a few weeks ago. See, I"m deleting the AC and smog. I have delete pulleys for both, but at the last minute decided my many electrical needs would justify a second alt. I have a second brand new CS alt from a good Ebay auction, and want to install it where the AC comp was.
I guess my question is, what the best way to wire in a pair of CS alts to a '77 wiring harness. I already have a line on the plug adapters but what do I do, piggy back them together and beef up the main wiring? I can wire them in parallel right?
P.S. Sorry to thread jack.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Originally Posted by Durango_boy
I liked the Coors Light Plug...
I'm installing a serp system on my '77, that came from a 1992 Z28. I will be using a CS for sure, and had a crazy idea a few weeks ago. See, I"m deleting the AC and smog. I have delete pulleys for both, but at the last minute decided my many electrical needs would justify a second alt. I have a second brand new CS alt from a good Ebay auction, and want to install it where the AC comp was.
I guess my question is, what the best way to wire in a pair of CS alts to a '77 wiring harness. I already have a line on the plug adapters but what do I do, piggy back them together and beef up the main wiring? I can wire them in parallel right?
P.S. Sorry to thread jack.
I'm installing a serp system on my '77, that came from a 1992 Z28. I will be using a CS for sure, and had a crazy idea a few weeks ago. See, I"m deleting the AC and smog. I have delete pulleys for both, but at the last minute decided my many electrical needs would justify a second alt. I have a second brand new CS alt from a good Ebay auction, and want to install it where the AC comp was.
I guess my question is, what the best way to wire in a pair of CS alts to a '77 wiring harness. I already have a line on the plug adapters but what do I do, piggy back them together and beef up the main wiring? I can wire them in parallel right?
P.S. Sorry to thread jack.
wiring them up in parallel will screw the regulators up, it's not the solution....
i am not a fan of the CS alts anyway, they run too hot...you maybe want to check out the 17SI series....108 factory rated, run all day without problems....
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Originally Posted by I'm Batman
I don't know, but I'd be wary of the CS130s. The CS144 alternators are fine, but they require a bit of bracket modification due to the larger case.
I will have to check, but I think the alts I have are the CS144s. I don't mind bracket mods so long as I can figure out the wiring.
I can't seem to find one yet either.
Drifting
Joined: Aug 2005
Posts: 1,289
Likes: 3
From: East Waterboro Maine
Did the alternator come with a QC card attached? I just bought a powermaster and it came with a card listing the volts and amps the alternator made during its final test. If it did, it may give you some clues.
Team Owner
Joined: Aug 2006
Posts: 24,125
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From: Columbia Missouri
Originally Posted by Maine Vette
Did the alternator come with a QC card attached? I just bought a powermaster and it came with a card listing the volts and amps the alternator made during its final test. If it did, it may give you some clues.
Who was that meant for?