Alternator
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
Reading your profile you have a big block 454.
I believe your clocking is correct for your application.
Your unloaded test results are low, should be around 14 vdc.
If the loaded test was done with both the HI Beam headlights and blower motor on HI that to looks low, should be in the mid 13vdc range
I believe your clocking is correct for your application.
Your unloaded test results are low, should be around 14 vdc.
If the loaded test was done with both the HI Beam headlights and blower motor on HI that to looks low, should be in the mid 13vdc range
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
Safety Car
Joined: Oct 2004
Posts: 3,921
Likes: 731
From: Youngstown Ohio
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
Yesterday My console battery gauge went over to 40 plus side then bounced around. Today it stayed just below 0. Yesterday Water temp gauge went up to normal. Today it didn’t move for a while then rose to where it should.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
Safety Car
Joined: Oct 2007
Posts: 4,360
Likes: 1,724
From: Seattle Area Washington
1100544 61 AMP All with C60 Air Conditioning
1100950 42 AMP L48 & L82 without C60 & LS4 without power steering.
1102353 42 AMP LS4 with power steering.
You stated you have a electric fan there are many variables there...
I suggest you purchase a new, not rebuilt alternator with a output at minimum 63 AMP and maximum 80 AMP "IF" your car still has the original engine and forward lamp harness wiring.
I can't see how the tester you used on your "IN CAR TEST" could determine what your loaded numbers are "without" actually loading the output?
How did it know if you had a 2 light system, 4 light system, LED lights, halogen lights etc???
I did see some videos on the tester you have, none of them showed the operator turning on lights, fan etc so it's not something you missed...
Race Director
Joined: Nov 2006
Posts: 13,151
Likes: 7,765
From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
2022 C3 of the Year Finalist - Modified
Cruise-In VIII Veteran
Electric fan?? Wouldn't consider less than 80 amp. Would seriously consider upgrading wiring if your running a electric fan.
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
Here are some 73 alternator numbers, there were 3 different alternators used depending on the cars options...
1100544 61 AMP All with C60 Air Conditioning
1100950 42 AMP L48 & L82 without C60 & LS4 without power steering.
1102353 42 AMP LS4 with power steering.
You stated you have a electric fan there are many variables there...
I suggest you purchase a new, not rebuilt alternator with a output at minimum 63 AMP and maximum 80 AMP "IF" your car still has the original engine and forward lamp harness wiring.
I can't see how the tester you used on your "IN CAR TEST" could determine what your loaded numbers are "without" actually loading the output?
How did it know if you had a 2 light system, 4 light system, LED lights, halogen lights etc???
I did see some videos on the tester you have, none of them showed the operator turning on lights, fan etc so it's not something you missed...
1100544 61 AMP All with C60 Air Conditioning
1100950 42 AMP L48 & L82 without C60 & LS4 without power steering.
1102353 42 AMP LS4 with power steering.
You stated you have a electric fan there are many variables there...
I suggest you purchase a new, not rebuilt alternator with a output at minimum 63 AMP and maximum 80 AMP "IF" your car still has the original engine and forward lamp harness wiring.
I can't see how the tester you used on your "IN CAR TEST" could determine what your loaded numbers are "without" actually loading the output?
How did it know if you had a 2 light system, 4 light system, LED lights, halogen lights etc???
I did see some videos on the tester you have, none of them showed the operator turning on lights, fan etc so it's not something you missed...
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
My little electric fan has been running off the current wiring with no issues. If I put an alternator with the same amp that's in there now, why would i need to update the wiring?
Race Director
Joined: Mar 2017
Posts: 11,906
Likes: 4,479
From: Virginia
Can you post a photo of the "little electric fan"? Do you still have your belt-driven clutch fan?
I got stuck in stop and go traffic for an hour, and was very happy to have a well over-spec'ed alternator to power the dual Spal fans. Each one is close to 15 amps. This alternator replaced the stock unit that could no longer charge the battery when the headlights were on.
I got stuck in stop and go traffic for an hour, and was very happy to have a well over-spec'ed alternator to power the dual Spal fans. Each one is close to 15 amps. This alternator replaced the stock unit that could no longer charge the battery when the headlights were on.
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
Can you post a photo of the "little electric fan"? Do you still have your belt-driven clutch fan?
I got stuck in stop and go traffic for an hour, and was very happy to have a well over-spec'ed alternator to power the dual Spal fans. Each one is close to 15 amps. This alternator replaced the stock unit that could no longer charge the battery when the headlights were on.
I got stuck in stop and go traffic for an hour, and was very happy to have a well over-spec'ed alternator to power the dual Spal fans. Each one is close to 15 amps. This alternator replaced the stock unit that could no longer charge the battery when the headlights were on.
Safety Car
Joined: Oct 2004
Posts: 3,921
Likes: 731
From: Youngstown Ohio
Electric fan ?.....I missed that part. Definitely upgrade your alternator. Over 63 amps. You don't have to go extreme, but consider a 100 amp one. Also, once you add an electric fan, your amp gauge will not register correctly. Consider a volt gauge instead if you want accurate information.
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
Electric fan ?.....I missed that part. Definitely upgrade your alternator. Over 63 amps. You don't have to go extreme, but consider a 100 amp one. Also, once you add an electric fan, your amp gauge will not register correctly. Consider a volt gauge instead if you want accurate information.
Safety Car
Joined: Oct 2004
Posts: 3,921
Likes: 731
From: Youngstown Ohio
The small fan was on there when I bought the car and has run fine with it for 3 years. It's also the alternator that was on the car. I've had no issues with any of it until now. Why can't I just put a new one on there like the one I have if I can determine the number on it? If it turns out that it's a 61 amp, can't I just put a 63 amp on it? If I go to a 100 amp, wouldn't i have to upgrade the wiring?
Race Director
Joined: Mar 2016
Posts: 14,305
Likes: 8,110
From: Napa Valley California
When I purchased my DeWitts radiator and electric fan set up, DeWitts suggested going to a higher amperage alternator.
I have a 73 big block coupe and upgraded to a Power Master 100 amp alternator.
The need for a larger output alternator comes into play when your electric fan kicks on and draws a momentary serge of power at idle when your alternator is putting out the least amount of amperage.
Once the fan is on and running the power draw is minimal.
If you are sitting in traffic for any length of time and your electric fan is coming on and off as it should, the stock alternator may not be able to keep up with the load.
You may just be sneaking by or this has been an issue that has shortened the life of your alternator.
If you need to replace the alternator you have now, I would do the upgrade and be done with it.
When you do replace the alternator be sure to match the proper wiring on the connector.
Some alternators are a one wire connector and some are a three wire connector.
Some alternators require the use of an amp gauge and some require a volt gauge.
I have a 73 big block coupe and upgraded to a Power Master 100 amp alternator.
The need for a larger output alternator comes into play when your electric fan kicks on and draws a momentary serge of power at idle when your alternator is putting out the least amount of amperage.
Once the fan is on and running the power draw is minimal.
If you are sitting in traffic for any length of time and your electric fan is coming on and off as it should, the stock alternator may not be able to keep up with the load.
You may just be sneaking by or this has been an issue that has shortened the life of your alternator.
If you need to replace the alternator you have now, I would do the upgrade and be done with it.
When you do replace the alternator be sure to match the proper wiring on the connector.
Some alternators are a one wire connector and some are a three wire connector.
Some alternators require the use of an amp gauge and some require a volt gauge.
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
Yes, you can just replace what you had. It may be all you need to repair. But, do you know how many amps is your electric fan is pulling?......Perhaps your alternator was being strained.........Was your amp gauge truly accurate? You won't pull 100 amps unless you have a 100 amp load. The extra is just for insurance if needed.