My 85 Cutlass Supreme Brogham Coupe with 68K miles still has the original alternator ("generator"). With the (converted) a/c running and at idle, the turn signal flasher is VERY slow. Was originally equipped with rear defogger. I'd rather replace the alt than rebuild it, and possibly upgrade it. Any suggestions as to a replacement alt/upgrade of the 78 Amp original 12si Delcotron? Are there any recommended wiring upgrades if I go higher than 78 Amps? I'm not looking for anything as high as 140, but thought I'd ask. It's in a warm climate currently, with no aftermarket addons besides the converted a/c, which is run constantly. Thanks!

 

You can get aftermarket versions of the 12SI that go to 100 amps or more. You can also get a CS130 that bolts to your existing brackets. These came from the factory with 105 amps. NAPA sells a short harness that adapts from the CS130 plug to your 12SI plug in your factory harness.

In any case, 78 amps should be plenty for your car. I suggest you start looking at ground wires and ensuring that all connectors are clean. I have the same 78 amp 12SI in my 84 and it has no problems keeping up with the factory power options, including stereo, A/C, and rear defogger.

 

Thanks for the tips! Overdue for a wiring check and clean...

 

Stock ALT should be plenty for a stock car, or even with some mods. If you added electric fans, then that is different...

Do a test by measuring voltage at the battery and the alternator both at high load (AC on high, lights and brights on) at both idle and 2000RPM. As long as the voltage is above 12.8, ALT is working as it should.

BTW, even my Caddy's owner's manual makes it clear that at idle, that lamps may dim SLIGHTLY when AC is on high or other power hungry accessories are on.