When do you need to upgrade the alternator???
 

My dad's 74 owner's manual indicates 66 Amps, or optional 88 amp unit.
The chassis electrics are basically stock, except for 55/60 headlights, normal radio, Odessy smuggler's box battery and twin EDIS ignition, (2x20 amps) and EFI, (13 additional amps).
AC was deleted in favor of a front cooler, but may go electric AC if i win the lottery.
I've built and wired a few houses, but sizing the electrical panel and sizing the alternator are clearly different.

Appreciate any advice,
chris

If you go electric AC you'll probably go the Classic Retrofit way. They sell an upgraded alternator suited to requirements of their electric AC.

I upgraded to Classic Retrofit. I have a voltmeter in my car and would watch the volts drop whenever the a/c compressor cycled on (Griffith's 4 condenser system w/electric fans on three of the condensers). This combined with headlights, upgraded stereo amplifier, etc drove me to the high capacity alternator. Very happy with it.

Here is the link: https://www.classicretrofit.com/en-us/collections/upgraded-alternators/products/copy-of-porsche-911-high-output-175a-alternator

If you get a fan housing with the thinner back spacer, not Carrera, but SC 80/83 you can use the larger alternator with on board VR.
Bruce

How much, is enough, (AMPS) ??
 

Thanks Guys,
Classic Retrofit makes solid stuff - I've got their fuse panels installed.
Bruce, You've been around the block a few times, Without electric AC, how big an alternator do you think will work, given my set up??
Thanks,
chris

add up the ants of everything that uses electricity and multiply by 3.
100 watt high beans = ~9 amps each or 18 amps
cdi or msd ~ 5 amps
~running lights
radio
etc.
alternators are designed to duty cycling, on and off, and from what I can determine my 75 was designed for 33% on and 66% off.
of course when you start the car the alternator will run 100% of the time for a bit to get the battery recharged but once that is done the alternator will run about 33% of the time..
I assume it needs time to cool off.
175 amps would be great but a 70 amp should get you about 33% unless you have a super large amp and maybe electronic suspension with hydraulic pumps.

Without going to Carrera, I prefer the 80/83 unit with onboard VR and it’ll install on all housings from 75 on with the 19mm back space. The heavier threads on the shaft and the 8mm Allen center is a plus too.
Bruce