I have noticed that my alternator might not be powerful enough for my car. i am not sure if it stock or what. it was on the car when i bought it, and after the 302 swap i didnt see a need in changing it out What is stock Amperage for the stock alternator....and\ what is a good replacement for now adays. i have an optima battery in it reasons 1. turn signal on and the amp draw on the ampmeter bounces up and down all over the place... 3when idling 2. hit the brakes and the ampmeter bounces all over the place when idling when everything is running at idle, stereo, fan, turnsignals...it starts charging the battery as if the battery is going dead and whn i drive down the road the charge goes off and shows full battery. i am sure that a good 70 amp alt woudl work, but what are some alternators that you all have used or do use in your mavs.... thanks
The stock alternator puts out about 15 amps at idle and 60 amps max. I just a bit ago finished installing an alternator from PA Performance. It puts out 60 amps at idle and is rated at 95 at speed with 120 amps max draw. It does everything it is supposed to do and well. I was impresed when I put the voltmeter on after I finished the install and turned everything on at idle. It does what the manufacturer says it'll do. I highly recommend this system.
Some of the early cars with manual trans and no air had only 35 amp units (like mine). Almost no output at idle, ran off the battery at stop lights. I installed a GM 80 amp 1-wire unit I got from JC Whitney on sale for $70.
My original Motorcraft was a 38 amp.....j-u-n-k. Then I put in a 61 amp motorcraft....slightly better junk. Finally had enough and put in a Tuff-Stuff GM 10si aftermarket 100 amp hooked up with the ignition turn on wire and the voltage sensing wire.....excellent. The old external regulated ford alternators are simply too weak to be of any use. Although the new 3G alternators by PA Performance are great (as described by Wes). After putting the headlights on relays, and all high drain items (nos solenoids, 2 stereo amps,electric fan) on a underhood fused panel block....I finally have a decent system. The small original 12 guage power wire that feeds the rest of the car (dash, interior lights, tail/brake lights, and heater fan) no longer has to carry the high drain items. Despite the good performance from the 10si....the PA units also look great and probably makes even more power at idle than the high amp 10si (40 vs 50-60 for the PA).
I pitched the voltage regulator and all of the wiring attached to it. Ran a 8 AWG wire from the rear of the new alternator to the battery side of the starter solenoid. Really cleans up the looks of the engine compartment.
