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On my 79 with a 5.0 i'm running a lot of accessory big, stereo fans fuel pump and my 75amp Alt is not pushing enough amps. when i'm sitting at a stop light and turn my flasher on I can hear my pump and fan surge really bad.
How big of a Alt can I ad to my truck with out burning my wires out.
I was thinking about one of the 140 amp alts they sell at Summit or jegs.
What do you guys think?
Thanks a bunch
You can put as large a alternator as you want, but you are correct, you will need to upgrade the wiring. A large alt will do no good with small wiring.
Speaking of which, that could be your problem right now. How do you have all this high amperage stuff wired up? You could possible do a little re-wiring, and with a little bump in idle speed, be ok with the alternator you have now.
Try replacing the alt to battery wire, the motor to chassis, and the chassis to battery wire with at least 4ga wire. If you still want a bigger alt after that, figure out what your draw is. If the 75amp alt is stock, the I'd suspect Ford to have spec'd it around 65 amp draw. Add your accessories to the 65 and this will get you close to your power consumption. Then add a little head room for future upgrades and you'll have your alt picked out.
With those Powermaster Alts, pick Natural, black or polished finish. Other coatings hold in heat and can cook the bearings. The 140's can usually take the heat, but the 200s were always problems for us with any coating.