ettev

Besides the obvious smart-butt answer, what are the differences between a 42 amp and 61 amp alternator?

For my original 1970, 42 amp alternator can I rebuild it using the 61 amp internal parts such as voltage regulator, rectifier, diodes, brushes, capacitor, etc and get 61 amps out of her? Or are the stator and rotor units different from the 42 to 61 amp units? Looking at the GM parts book, it appears as if I install a stator from a 61 amp unit in my 42 amp unit that all other internal components are the same between the two.

Can anybody confirm this or let me know if they've done it? I want to keep my case looking stock and indicating a 42 amp unit, but want more juice out of her.

Thanks in advance.

ettev

Up ya go.

ROD NOCK

You can use the 61A guts for rebld, and use the 42A case and rotor as this will give you a 61A alt.
You should mark inside the case as to what you've done, so future rebuilders won't freakout. :eek:

KenSny

Ask these guys, maybe all you need to do is move the diodes. That's all that you need to do to upgrade a 61a to an 80a.
http://www.alternatorparts.com/

GaryS

You can make the guts of your alternator just about any amperage you want, within reason. I had a 66 alternator rebuilt to 100 amps. Same coast as the orginal low amps.
Gary

Sigforty

Where do yall get the rebuild kits? I figure after I get my car back I am going to need a more powerful alternator.

lars

The amperage output of the alternator is determined by the number of windings in the rotor and stator. You can't increase output by switching regulator or diodes - that will do nothing for you. The regultor does not control amperage output - it controls voltage. In order to increase amperage, you have to switch out the rotor and stator.

ettev

So are the rotor and stator from a stock 61 amp GM alternator the same physical size as the 42 amp unit? In other words, will they be a direct swap fit, or are they larger?

mrvette

lars, in fact i'ts a matter of the wire gauge, diameter, more than the number of turns....but that may vary a bit dependinng on what the regulator is capable of, ....and of course the physical limitations of the space available for the wire in the iron ring comprising the stator....fatter wire is more space and less room for good magnetic coupling....these factors all add up to just why the CS series alternators are so poor in reliability...the biggest factor is cooling...and small diameter alternators have no room for airflow, making thicker wires and small airgaps for the magnetic coupling, and more powerful magnets out of the rotors (through the regulator, that's all the regulator does...increase and decrease the field strength of the rotor, thereby determining the VOLTAGE output of the stator)....and of course through the crappy diode/rectifier packs for the final output....

it has been shown to my by local reputable rebuilders over the years that the only type diode packs worth a damn are the type with welded leads, they seem to withstand the internal heat and lack of cooling much better than the soldered types.....as they show signs of gross overheating to the point of either melting or oxydizing the solder and opening up the connections....

I say the best arrangement would be an external diode pack....but that's another story/thread....

so back to the starting sentance....i'ts the gauge of any wire that determines the current it can carry,...that and the available cooling....if there is inadequate cooling...like any small diameter alternator putting out the same power as a larger alternator...the small one will fail much sooner.....no debate...it's laws of physics....
sorta like ricers vs HEMIs or BBCs....etc....

GENE

ROD NOCK

Assuming you have the same (10) series alt, it should be the same, GM built both a 42 amp and 63 amp ratings in the 10 series. But to verify this, the part no.s would have to be checked. The next easiest way is to measure inner/outer stator diameter, rotor diameter/depth. So to verify, take the 2 units apart, and measure both stators and rotors. Check the cases for same physical features too. This will tell you for sure if the physical fit will be compatable. Don't forget to mark the outside of the cases (upr and lwr) before disassembly so you reassemble them the same!
Good Luck! :chevy

SteveG75

I used a kit from http://www.alternatorparts.com to rebuild my 42 amp into an 85 amp. Same rotor, different stator. Took about 45 minutes including pulling the alternator out of the car. Works very well when the Spal fans kick in, especially at night with the lights on.

Spook

Since no one else said it...

About 19 Amps!!! HAHAHAHAHAHA.. :crazy:

Hopefully you got your answers. Personally I dont see any reason why the guts of the 61 wouldnt be interchangeable with the guts of the 42. But then wouldnt it be a female canine if you only got 51 amps. :crazy:

Spook
:reddevil