I need a new alternator for my 69 big block chevelle, my old alternator was a 55 amp, I was wondering if it would be a smart to upgrade to an 80 or 100 amp? Also, if any one knows of a good place to get an alternator or a good brand please let me know. Thanks.

napa sells a good one.As far as putting a higher amperage ,it all depends if you run big ass sound system,electric rad fans or air cond.If so , your answer is yes

I need a new alternator for my 69 big block chevelle, my old alternator was a 55 amp, I was wondering if it would be a smart to upgrade to an 80 or 100 amp? Also, if any one knows of a good place to get an alternator or a good brand please let me know. Thanks.

What kind of charging system do you have currently, externally regulated (which is original) or internally regulated?

I need a new alternator for my 69 big block chevelle, my old alternator was a 55 amp, I was wondering if it would be a smart to upgrade to an 80 or 100 amp? Also, if any one knows of a good place to get an alternator or a good brand please let me know. Thanks.

You are gonna need bigger wires under the hood in the charging circuit when you get to the 100 amp range. Don't fool with these 1 wire alternators...dumb move.... they don't perform at low engine speeds. They are meant for farm equipment with little or no accesories. They look cute with just one wore but they realy are impracticle for street use ESPECIALLY with a lot of accessories like a radio and a heater, signal ligts and other things that ya need everyday. Just not a good idea for low RPM operation in town.

A one wire doesn't start charging till you hit 12-1500 rpm and that is the knock on them. I put one in my street rod in 1999 and it has worked flawlessly since. I also put a 100 amp model on my Chevelle back in the spring and it has worked fine. I usually rev to 2000 or so within a few minutes of starting my cars.

I got a chrome 100 amp unit off Ebay for $67 + $10 shipping. I believe they are now making a unit that charges higher at idle. A friend has one of those ordered for his 32 ford which runs fans and air and hasn't been charging enough. I will know more about after he gets it and uses it for awhile. The 100 amp 1 wire requires a #8 wire from the alt out to the + battery cable.

If the 55amp alt kept the battery charged well enough for good hot starts prior to it going bad then you dont need any more amps & can keep it simple in that case.

But if your planning on installing items that will put more load on the charging system in the future then ni would opt for 70-80 amps for some breathing room.

I had the stock original 37 amp alt on my 69 rblt & upgradded from 37 to approx 70amp at my local automotive starter/alt rebuild shop.

That would be the easy way to upgrade your alt for better/faster battery charging/recovery which is especially good inbetween mult starts @ night and if you have been in traffic with a fair amount of idling so you get quicker battery recovery when you get moving again.

I have also seen brand new (not rblt) alts on ebay that i think were 55 & or 63 +amp for like $60-$70 if you dont care about matching #'s.

Scott

Thanks for the help guys, sounds like this would be a good time to upgrade, for the future.

1964 through at least 1967 Cadillacs had an external regulator 70 amp alternator that is cosmetically and physically identical to your 37 or 55 amp Chevelle alternator. It is a direct bolt - in, but puts out an additional 15-23 amps. I believe the large body B-O-P products from the 60's and early 70's would do exactly the same thing.

For my part, I find this to be a nice upgrade in that keeps it stock appearing, but give a bit more performance. BTW, all V8 Delco alternators from the 1960's are physically interchangable for GM products. Same bracket holes, same wiring, same physical size for stators, rotors, etc. just make sure you have the correct pulley. Pulleys are also interchangeable.

If you are worried about numbers matching or keeping your "original alternator" in your Chevelle but really need the extra juice, here's a tip. Disassemble your 55 amp alternator, swap the stator, rotor and diode assembly from a Cadillac 70 amp into your numbers correct stamped Chevelle housing. No one will know but you, and you'll have a 70 amp output in a 55 amp numbers matching housing. Kind of a "sleeper" upgrade. :-)

As far as finding a hi amperage Delco externally regulated alternator for parts to do the swap, I believe the first design OEM GM internal regulator appeared in 1972 or 1973, so any pre-72 GM V8 Delco products should be fine. If you must do this on the cheap, then good reusable Delco alternator cores still fairly easy to find at the boneyard, and are really cheap there. Also, you can sort through the rebuild cores at your local auto parts store, (if you are friends with them and if you know what you are looking for.) In my experience, Delco stators rarely fail, so you're really just looking for that 70 amp stator. Find one at the boneyard or core bin at your local auto parts store. Just bring something fairly close to replace the core you want, or buy it outright, if they'll let you. Buy the diode set new. Buy the proper diode set new for the heavy duty alternator. Don't put your old diode set from your 55 amp alternator on a 70 amp stator. They won't handle the current and will eventually fail, plus new USA made diodes are actually superior to the 30 year old diodes, due to improvements in diode manufacturing technologies. (imagine that!)

Alternators are easy to rebuild, and Delco rebuild parts are far better than Chinese copies. Do it yourself and end up with a high output American-made alternator that will serve you for years, rather than one of those Chinese copies that wear out in a year or two, due to bad metallurgy, imprecise tolerances, and slave-labor produced electronics with poor operational tolerances. All the 1960's early 70's Chevelle shop manuals have instructions for alternator service, which will show you how to do it.

In spite of what some other folks said on this post, I must say that I prefer internally regulated OEM GM alternators, (Not Chinese copies) but if you must run an external for some reason, I strongly recommend that while you are at it, you upgrade your external regulator on your Chevelle to an electronic regulator. I believe a Wells VR715 is aboug 12 bucks? It is also a direct bolt into your stock harness. If you must use an external regulator design, be aware that electronic regulators are far superior to mechanical regulators in terms of system performance.

Why electronic regulation? Well, first, your alternator's amperage rating is only part of the equation. Cyclical regulation of the alternator's output by a mechanical regulator means that the alternator in reality has a duty cycle (it's either on or off as the mechanical regulator sets a low voltage point when the alternator "kicks on" and a high point where it "kicks off") In contrast, electronic regulators maintain a precise reference voltage to your alternator at all times, causing it to work "just enough" to keep the system at the optimum charge point. The end result is extended alternator life, better battery life, and more stable operation of your electrical accessory systems, plus you eliminate electronic noise caused by arcing of those clattering coils in your mechanical regulator. (That's on reason why there's a condenser on the stock regulator, besides being there to extend the life of the points in your regulator.)


Finally, I read with interest the several comments here indicating that "one wires (internally regulated) GM alternators don't charge at low rpm". I have run many first-design OEM GM internal regulator alternators, such as those found on mid 70's and up Impalas, GM trucks, and other V8 GM applications, and they most certainly charge at all engine RPM. I cannot, however, vouch for Chinese copies that are being sold on ebay, or later model OEM, which easily could have a low RPM limit switch. Nevertheless, there ARE OEM GM internally regulated alternators which do not drop out at low RPM. You just have to find them.

Cheers,

cbg

1-wire does charge at low rpm just needs revs to start working. loss of light (2nd wire) circuit causes this.

1-wire also does not include a voltage sensing circuit so it does not compensate for voltage drop in charging wire. add 3rd wire for this feature. this can be important at idle with high current demands.

Peter