70amp alternator for 85

[Isaac G.]

Good Evening to all,
I have been trying to trace a battery drain for a bit with my limited abilities, this was my last effort before taking it to the mechanics. I had my old aternator 70amp checked at the local auto parts store, no reading. I decided to replace with an 85 amp from napa. Once installed the idiling dropped from 10000 rpms to 6000, the interior lights fluctuated and when the headlamps where turned on the car stalled.Also when depressing the accelerator the car would not respond as it did before with the old. When the alternator was picked up the setting for the connector was wrong, the person at NAPA took the alternator apart and made the correction. Is the increase the cause of the rough idiling and fluctuating or perhaps the seller did something wrong when he made the adjustment? Please help.

[Edward J.]

Re: 70amp alternator for 85

Issac, the 85 corvette Idle speed was always very low, generally about 550/600 rpms, the cold start up idle was always alittle higher at first then would settle down after a few seconds (1100/1300). The charging system output should be abut 13.8-14.2 volts. your gage in the car should show this with the engine idling. generally speaking the state of charge of the battery is why there is a variance of the charging voltage.

As for the stalling I would try and clean the throttle body opening sometimes a little carbon will build up and cause idle and stalling problems.this is a smiple task, remove the rubber intake hose and open the throttle blade wide open and take a rag with some carborator clean and clean the opening, upper and lower parts of opening.

Hope this helps Ed

[Terry M.]

Re: 70amp alternator for 85

Issac, the 85 corvette Idle speed was always very low, generally about 550/600 rpms, the cold start up idle was always alittle higher at first then would settle down after a few seconds (1100/1300). The charging system output should be abut 13.8-14.2 volts. your gage in the car should show this with the engine idling. generally speaking the state of charge of the battery is why there is a variance of the charging voltage.

As for the stalling I would try and clean the throttle body opening sometimes a little carbon will build up and cause idle and stalling problems.this is a smiple task, remove the rubber intake hose and open the throttle blade wide open and take a rag with some carborator clean and clean the opening, upper and lower parts of opening.

Hope this helps Ed

I strongly urge you to use throttle body cleaner and not carburetor cleaner. Some throttle bodies have a coating on the inside that is attacked by some carburetor cleaners. I don't know which years of Corvette (if any) have that coating, but I prefer not to take chances.

[Isaac G.]

Re: 70amp alternator for 85

The car is an 82 colletor, and I was surprised with the low idiling because it wasnt an issue with the old alt. The battery is only 7mos. old, but with the drain downs and recharging maybe there might be a problem. Tomorrow I will do the cleaning and see what changes. So the increase in amp. should not effect the low idiling issue and fluctuating interior lights?
Thank you members for your time and help. Goodnight

[Joe L.]

Re: 70amp alternator for 85

The car is an 82 colletor, and I was surprised with the low idiling because it wasnt an issue with the old alt. The battery is only 7mos. old, but with the drain downs and recharging maybe there might be a problem. Tomorrow I will do the cleaning and see what changes. So the increase in amp. should not effect the low idiling issue and fluctuating interior lights?
Thank you members for your time and help. Goodnight

Isaack-----


Using a higher amperage alternator should not cause any problems with idling or, for that matter, any other electrical problems. However, I'm surprised that you were able to install an 85 amp alternator for a 1982 Corvette application. Usually, alternators of that size are a different design and configuration than those originally installed on a 1982 Corvette.

[Isaac G.]

Re: 70amp alternator for 85

Hi Joe, when I removed the original alt. it was a Delco-Remy, and my hopes was to replace it with the same. In our area the most common auto stores are Advance Auto, Discount and NAPA, the Chevy dealer told me that the alt. was discontinued. All except NAPA had the exact identical one which I found threw there web site. When I recieved it, the setting was different but the counter person corrected it on the spot. Today I returned to have the alt. checked because of the problem i posted yesterday and all checked out fine 14.2 volts. So my next check is with the connector and voltage regulator, NAPA has a rebuilt kit for the connector if needed. Also I checked the car out this morning to see how the battery charge was and I was happy to see the dome light on and the car turning over, where previously this was not the case.

[Joe L.]

Re: 70amp alternator for 85

Hi Joe, when I removed the original alt. it was a Delco-Remy, and my hopes was to replace it with the same. In our area the most common auto stores are Advance Auto, Discount and NAPA, the Chevy dealer told me that the alt. was discontinued. All except NAPA had the exact identical one which I found threw there web site. When I recieved it, the setting was different but the counter person corrected it on the spot. Today I returned to have the alt. checked because of the problem i posted yesterday and all checked out fine 14.2 volts. So my next check is with the connector and voltage regulator, NAPA has a rebuilt kit for the connector if needed. Also I checked the car out this morning to see how the battery charge was and I was happy to see the dome light on and the car turning over, where previously this was not the case.

Isaac------


If the alternator you removed was the original alternator, I hope you didn't turn it in for a measly $10-15 core charge. I would save it and have it rebuilt. If you still have it, what are the stamped numbers on it?

By the way, all C3 alternators were Delco-Remy and virtually all rebuilt alternators will use Delco-Remy cores

[Jim T.]

Re: 70amp alternator for 85

Hi Joe, when I removed the original alt. it was a Delco-Remy, and my hopes was to replace it with the same. In our area the most common auto stores are Advance Auto, Discount and NAPA, the Chevy dealer told me that the alt. was discontinued. All except NAPA had the exact identical one which I found threw there web site. When I recieved it, the setting was different but the counter person corrected it on the spot. Today I returned to have the alt. checked because of the problem i posted yesterday and all checked out fine 14.2 volts. So my next check is with the connector and voltage regulator, NAPA has a rebuilt kit for the connector if needed. Also I checked the car out this morning to see how the battery charge was and I was happy to see the dome light on and the car turning over, where previously this was not the case.

Isaac the voltage regulator is inside the alternator of the one you just purchased and the one that you replaced. They are not difficult to change.

[Isaac G.]

Re: 70amp alternator for 85

Yeah Joe, I turned in the old which I believe was the original, didnt know better. This is my first project and Im learning as I go along, I had considered rebuilding but didnt know when I would get around to it and it wouldve been a first. So, replacement was the quickest fix for me right now. They gave me 25.00 in return for the core.
Jim thanks for the info I thought it was a separate part, I was heading for my chiltons to look for it, so tomorrow I will check the connector.
Can I get some advice on the procedure for the throttle body cleaning?

[Joe L.]

Re: 70amp alternator for 85

Yeah Joe, I turned in the old which I believe was the original, didnt know better. This is my first project and Im learning as I go along, I had considered rebuilding but didnt know when I would get around to it and it wouldve been a first. So, replacement was the quickest fix for me right now. They gave me 25.00 in return for the core.
Jim thanks for the info I thought it was a separate part, I was heading for my chiltons to look for it, so tomorrow I will check the connector.
Can I get some advice on the procedure for the throttle body cleaning?

Isaack------


If you get back there quick, they might still have it in their core-stock. They don't ship this stuff out every day.

[Isaac G.]

Re: 70amp alternator for 85

I spoke to the saleperson. Monday I will talk to the manager and have him request it back from the warehouse, it had already been picked up. Thanks for the heads up.

[Isaac G.]

Re: 70amp alternator for 85

Had the alt. re checked, 14.2, installed it and no more battery drain down.
The car still wouldnt start, Why-because no fuel.....duhhhhh, refueled, throttle cleaning and she's running much better. On the flip side, original alt. gone, unable to retrieve. Thanks again for the inputs. Now to tackle the brakes.

[Edward J.]

Re: 70amp alternator for 85

Isacc, There maybe many of the 82's out there with a correct numbers Alternator. keep your eyes peeled for maybe a rebuildable one, junk yards, e/bay etc.

[Isaac G.]

Re: 70amp alternator for 85

Hi Edward, Hope all is well. What are the numbers I am looking for?

[Edward J.]

Re: 70amp alternator for 85

Isacc, I don't know what the numbers is on you car. do you have a judging manuel for your year car? If not there worth the investment, It details everything you'll want to know when restoring your car.