I have a 69 with a 350. I also have added Air Conditioning and an AMP to the radio. I have a charge of 14.0+ with the amp running but when I turn my AC on it drops too low.

So I know I need a higher amperage alternator but what size should I get?

Also, I have a three wire system with an external voltage regulator. I am wanting to stay with a three wire system but I am getting confused on what I should get or the way I should go with it.

Thoughts?

SAM

I think the 10DN is rated at 40 amps in most cases.

I think the 10DN can be upgraded but I would consider changing from externally regulated to a 10SI or 12SI internally regulated.

So what are the advantages to changing and what parts are needed for the change?

I found a Mr Gasket 5123 that is pricey but chromed and is a direct swap. It is an 80 amp alternator.

Normally a one wire will go directly from the alternator to the battery and take out the ignition switch and the dummy light wiring. I think some may have a work around on the dummy light but I don't know which ones. Also, the ignition wiring isn't needed on the one wire models.

So again, why change and what is needed? Please send links to the parts.

Make a case, I would welcome more info on the subject.

SAM

You need the alternator that was used for the A/C cars. It's a 55 amp version and I have an external voltage regulator. You can get a rebuilt unit from any parts store if you don't need the numbers to match. Just be sure it's the 55amp version.

The casing is different for the external vs. internal voltage regulator versions, so be sure you get the right one.

Mark.

Non A/C cars had the 37A alternator.

http://www.autozone.com/starting-and-charging/alternator-performance?number=5123&searchtext=5123

This is an 80 amp but rated output of 60 Amps. With my AC and small stero amp it should work good. I am going to order it and see how it works out. Easy return to Autozone if there is an issue.

SAM

So, you never told us what "too low" was as far as V output

It was 12 or less. I will let you know how the new alt works. My existing alternator was a 37 amp one. The new one should work great. I will let you know how it works out. I should have it in 3-5 days.

SAM

Want to add that the casing is different between the external and internally regulated versions. The plug is different too, so be sure you have the correct case. When I clicked on your link the usage was for 1973 and up, which makes me think you have the internal regulator version ordered? Just double check, you might want to go into an Autozone and see it first hand.

Your best solution is to listen to dabird. A/C cars had 55 amp alternators. The outside is identical to the 37 amp you have and your regulator will work just fine.

There's no reason to put an internally regulated alternator on your '69!

The 5123 is externally regulated and a 3 wire system that is 80 amps but puts out 60 amps. Which should be perfect since I have an AC car with an additional amp. This is a direct swap for the 69. It also fits 3,233 different models/years of cars including 1,186 different Pontiac models.

I also called the Mr. Gasket Tech Rep and he pulled one off the shelf and physically looked at it. This same style works in many different years as well. I have another link to O'Reilly's website showing more specs. I also got the thing highly discounted from the Autozone's website with free shipping and 25% off with an additional $10 off. Also, by buying it from Autozone, all I have to do is walk it back in for a refund if I don't like it.

It should work great. Can't wait to get it.

SAM

http://www.oreillyauto.com/site/c/detail/MRG0/5123.oap?ck=Search_5123_-1_-1&keyword=5123

Read the amperage NOT the voltage when running things, you should see close to 60 Amps on a 55 amp nator with stuff running...

I got the new alternator installed and it works great. Mr. Gasket informed me the 5123 was the alternator I needed for my application and they were correct. Direct swap and looks great. With the car running at idle it reads about 15 Volts. When you turn on the AC with the Stereo on and all electrics it sits right at 14.1 or so.

SAM

Here are some pics.

Did you have to change the pulley to the one off your stock alternator, or was there enough adjustment on the brackets? I'm looking for an alternator, but I don't need the chrome dressed up version. Do you know if they make the same model in just the standard finish? A model number would help as well if anyone knows. thx

If I remember correctly, it is slightly a different size. However, I just went to the local auto parts store and picked up one that fit. It works great. Also, I am pretty sure you can get one without the chrome.

SAM