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wdaly

Alternator/Generator Upgrade

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Is it possible to up the output on my 88 Coupe (aka-Monte Carlo)?

I have installed a digital voltage gauge some time ago and it will "flash" when the demand exceeds the capability of the alternator. ie. it will flash when it reads below 12 volts as a nice warning that I had better start turning off stuff. In winter that stuff includes rear window defogger grid, defroster fan, wipers, lights... Summertime is not much better with the AC on sitting at a long stoplight.

My understanding is I probably have a typical 40-45 Amp system? We all know our friendly neighborhood cops have enhanced electrical systems - so - what would be involved? Is it just a matter of fitting in a, I assume, physically larger unit?

Bill D

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If your stock alternator isn't up to the job, it may be because of a bad internal regulator, slipping belt. etc. It would be hard to imagine your alternator can't handle the load of factory options.

I'm guessing your stock alternator is probably in the 65 amp range, maybe a bit more. The stock Prestolite in a Stude Avanti was 40 amp back in '63.

If you feel an upgrade is necessary, you could probably go with up to about a 105 amp alternator without having to upgrade your car's wiring. Look at either Summit Racing or Jegs catalog for replacement alternators with built-in regulators. They should bolt right on, but you might have to use a different length belt, but maybe not.

On my '70 Avanti a 105 amp alternator was added with the crate engine and the additional amperage created no issues for the stock wiring harness.

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Is it possible to up the output on my 88 Coupe (aka-Monte Carlo)?

Yes but it shoudn't be nessesary. Larger amp alternators can be used, will look and bolt up the same.

My understanding is I probably have a typical 40-45 Amp system? We all know our friendly neighborhood cops have enhanced electrical systems - so - what would be involved? Is it just a matter of fitting in a, I assume, physically larger unit?

The stock alternator is at least 80 amp rated. I have a '87 and have had no problems and I added an electric fan. I would say you have a alternator or battery problem. Alternator not producing enough amps or volts, or battery not keeping reserve. You need to have the charging system checked out, at 2000 rpm with a load you will produce max amps and around 14 volts.

I just replaced a truck alternator on a truck that produced max amps but only 12 volts. It would charge the batteries great but only to up to 12 volts, so they have been fighting a starting problem for a year.

Be aware that Avanti Motors wired up the electrical system kind of weird. I know my '87 does not match their wiring diagram, and I wouldn't trust the voltage gauge either. They show 3 seperate power supply wires, just like the Monte Carlo coming into the interior. There is only one on mine and it goes to the amp gauge first and then to the fuse box etc. On my '87 you can reach up behind the amp gauge and pull off the push-on supply wire and then you can't start the car, kills everything.

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Yes but it shoudn't be nessesary. Larger amp alternators can be used, will look and bolt up the same.

The stock alternator is at least 80 amp rated. I have a '87 and have had no problems and I added an electric fan. I would say you have a alternator or battery problem. Alternator not producing enough amps or volts, or battery not keeping reserve. You need to have the charging system checked out, at 2000 rpm with a load you will produce max amps and around 14 volts.

I just replaced a truck alternator on a truck that produced max amps but only 12 volts. It would charge the batteries great but only to up to 12 volts, so they have been fighting a starting problem for a year.

Be aware that Avanti Motors wired up the electrical system kind of weird. I know my '87 does not match their wiring diagram, and I wouldn't trust the voltage gauge either. They show 3 seperate power supply wires, just like the Monte Carlo coming into the interior. There is only one on mine and it goes to the amp gauge first and then to the fuse box etc. On my '87 you can reach up behind the amp gauge and pull off the push-on supply wire and then you can't start the car, kills everything.

Thanks I-Jim & G-Slinger:

Perhaps I should have mentioned that when I do overload the electrical system the belt starts screetching, but probably more important than that - this is the ORIGINAL alternator with 112000+ miles on it!

Perhaps I should consider replacing it in general.

Bill D

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When it screeches, that would indicate a belt problem...either stretched, glazed or not adjusted properly, or a combination of those. An alternator bearing going bad would be obvious at all rpm's.

The mileage certainly doesn't mean the alternator is in need of replacement. My daily driver has 114k miles on it and I have had no problems with the alternator, but that doesn't mean it can't go out tomorrow either.

Give the belt a good visual inspection. If it looks good, try spraying some silicone spray or belt dressing on the belt as the car is idling and with the rpm's being run up and see if the squeal goes away. If it does, replace the belt.

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Thanks I-Jim & G-Slinger:

Perhaps I should have mentioned that when I do overload the electrical system the belt starts screetching, but probably more important than that - this is the ORIGINAL alternator with 112000+ miles on it!

Perhaps I should consider replacing it in general.

Bill D

You shouldn't be overloading the system at all. Sounds as if you have a belt problem, with the ENGINE OFF take your thumb and see if you can turn the fan on the alternator without the belt turning, if you can the belts loose and may just need tightening. Hate to see you change a perfectily good alternator. I have seen many things that could cause your problem, loose belts, bad alternator, bad battery, corroded battery cables or a loose ground or positive cable.

By the way, ask for parts for a '87 Monte Carlo SS with a 5.0L HO engine. They didn't make a '88 Monte Carlo.

Jim Wood

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