DWinTX

Hi, I have a 70 350/350 w/AC. It's a rolling project, most of it is original and never restored as best I can tell. This weekend I drove it for the first time in about a month. It sits outside for now, and had rained quite a bit in that month. It was stumbling badly off idle, so much so that it would barley run. It revved OK in neutral, but wouldn't run under load. I checked under the distributor cap since it had been so wet, but it was dry.

I noticed that the ammeter was nearly pegging, and after shutting it down I heard the battery hissing. It was late and I didn't have any time to do testing, but I'm guessing the voltage regulator is gone. I've determined (correct me if I'm wrong) that this is 10si series (part# 1100884) alternator and found a number of rebuild kits on the Quick Start site.

They have several kits, some are just the VR, diode trio and brush holder. Others include a bridge rectifier and/or stator. The stator upgrades it from 61 to 80 amps.

So if you were going to rebuild it, would you get the bridge rectifier or stator? Here are the options I saw:

http://store.alternatorparts.com/10s...epair-kit.aspx
http://store.alternatorparts.com/10s...rsion-kit.aspx
http://store.alternatorparts.com/10s...epair-kit.aspx

Also, could the stumbling have anything to do with the overcharging? Before I noticed the ammeter, I thought the carb had gotten plugged up or something and swapped an extra Holley I had sitting around on there. I had planned on rebuilding the one that was on it anyway. Acted just the same. I have a Pertronix unit on it so maybe that could be affected by the overcharging?

Only other thing I could think of that would be the fuel pump not supplying enough pressure. The carb I put on had only been run for about 100 miles, though it's been sitting a while. Still seems unlikely that two carbs would show the same problem. Another possibility might be that water had gotten into the tank. The gasket on the cap is pretty brittle. Going to try some HEET for that.

lionelhutz

You can get away with only the cheap kit if the rectifier diodes check out OK. You might need the stator kit if you plan on adding extra load that requires the higher output. However, if you plan on that, I would recommend upgrading to a CS130 type alternator which can output more current at idle then your 10SI is rated to output.

DWinTX

About the only thing I plan on adding is a stereo. It was a radio delete car. I'll probably add an aftermarket stereo and maybe a small amp. No subwoofer or anything, just either 2 or 4 speakers depending on what I could fit in there.

lionelhutz

You'll be fine with the stock rated alternator then.

DWinTX

OK, thanks Lionel.

joewill

your bubbling battery may be overcharging..
check the output voltage of the alternator, both at idle and higher RPMs.. also test the voltage at load ( headlights/fan/wipers/AC full on)

Mike Ward

10si alternators are cheap and easy to rebuild. If you're going to the trouble of pulling it off the car, re-do it completely.

http://alternatorparts.com/repair_ma...-contents.html

DWinTX

Yep, that's what I did. Got the deluxe kit and a set of bearings.

LeMans Pete

That's a coveted little piece of equipment you have there, treat it with care.

DWinTX

I'm coming to realize that!. Funny how just a couple of numbers stamped in some metal change the value so much in this hobby.

That's why I decided to rebuild it. Originally I was just going to get a $40 alternator from the local parts store and slap on there, but when I realized what this one was worth I figured I better keep it on the car so I don't lose it.

Solid LT1

Naw! You should go with the CS130 and sell me that old junky alternator......

jb78L-82

Or you can do what I did which was remove the OEM alternator, rebuild it, and put it aside. I replaced mine with a CS-144 140 amp one that fit right in with no issues and is one of the best alternators GM used in recent years. Charges like a champ at idle. The only high amp draw I have on my car is 4 Hella Euro halogen lights 55/60 watt lows and 100 watt highs-the highs are on a relay pulling power directly from the battery lead attached to the alternator.

noonie

Nice lights.