They didn't have 3G alternators in the 60's, but they had air condition. Who said you had to upgrade to 3G? I don't know of any reason you would have to up grade to 3G but what Daze says makes a lot of sense.

Last edited by wsinsle (11/30/2013 10:55 PM)

Your car is already wired for the alternator it had from the factory.  A 3G might be a better alternator but, do you need one?  No, the one you have, or one justlike it wound for higher amps, will do the job just fine.

I have had an original type on my 66 forever, and I am running A/C, power windows and power locks.  Never had a problem with anything.

On my 66 F-100 truck, I am using a 3G alternator since I got one with a 5.0 serpentine setup I bought, plus I have to rewire the truck anyway.

The big difference in my book is you can buy a 90 amp original type alternator for under $100 and the 3G will cost you alot more, unless you find one you can trust from a salvage yard.

Sure, modern electronics are better than old stuff, right?  I just had to replace the electronically controlled radiator fan in my 2011 Ford Flex with 50,000 miles on it due to an electronic part failing.  The ability to design modern electronic systems that will go forever is surely there, but I think Ford and everyone else has built in some planned failures so they can sell their ridiculously high mark-up replacement parts.

hmartin025 wrote:

IMHO, a regular Alternator will work just fine. However a 3G alt has some advantages as stated.
Howard

+1    In most applications it is probably overkill.
Unless running a Taurus or larger fan, mine supposedly can pull up to 90 amps on hi speed startup.

Probably why MS doesn't have a problem with his.

I got a cool chrome one from Skip White Performance. 100% LIFETIME warrenty....no pro-rated Pep Boyz deal-e-o! Wayy better price too!
6sal6

I may be wrong, but I think he is adding AC to his car and he was told that he needs to upgrade his alternator (or generator?) to support the AC.   I think he is also asking whether he can just get a same type as original alternator but with higher amperage such as those seen on ebay....

If you have a generator, I would upgrade to an alternator.

If you already have the stock alternator, I would see if you have charging problems after the ac is installed before proceeding to swap it out. It might not even be an issue for you if you don't have alot of modern electrical drains on the charging system.

Some wiring mods might be needed if you decide to go with the original style alternator with the higher amperage. they are usually 1 wire setups, although some are not. Some are small case and others are large case which might require some trimming on a bracket.  I would be concerned about what the amp output is at idle and not just the total amps it can produce.  You don't want the battery to discharge at idle due to insufficient amps at idle. So beware the case size ( small or large), the wiring type ( 1 wire or original multiple wires), and idle amp output of stock alternators with higher amperages.  Also when ordering, get the correct pulley type, v belt or serpentine belt. 

Additional considerations:

Are you running underdrive pullies?  They will also affect charging at idle as well.

Do you have a dash cluster with the light or the amp gauge?  
 

I think yall are making the wiring change out to be harder than it is. Graft the harness coming off of the 3G alternator to the old alternator harness on the mustang. Yellow to black/yel (to the A terminal - doing it this way it reads the voltage at the starter solenoid for the regulator). Red/grn to white (to the I terminal). Cut the voltage regulator connector off and connect the white wire to the Red/grn wire(that feeds switched power to the alternator when you turn on the key). You don't need the ground wire in the original harness feed anymore. Connect the heavy feed cable directly to the starter solenoid and you are done.

Yes, it is overkill, but I have had too many cars over the years that the lights dim when I turn on the wipers, or the radio (really loud). I like always seeing the voltage at 14 no matter what. even with the radiator fan, heater fan, A/c fans on so the warm air blows on my face, the headlights, radio and wipers on all at the same time and still have plenty of power. I know if it stalls for whatever reason I will be able to start it again.

BobN