1971 Valiant, Help choosing what alternator amperage I need?

[Kolbjorn]

Hi, I have a 1971 Valiant. I am planning on adding AC to the car. I already have a 2 speaker system in the car (JBL GTR-104). While I am converting the front brakes to disc, I decided to check my alternator because I've also had some charging issues. I take it to auto parts store, and it reads 'failure'. The computer didn't give any information on how many amps it was generating.

So I want to get a new one. But since I plan on adding an underdash AC, a thermostatic controlled elec. fan later and with my speaker system already installed I figured I need a higher power alternator. Maybe someone has done similar modifications to their car and could point me to how many amps I need? I see ones online at 95-110 amps. Do I need that much? I've read that higher power amps can melt stock wiring, so I plan on upgrading the wiring. Any help would be appreciated. I looked around on here for a little before posting but couldn't find anything however if someones already covered this I'm sorry. Thanks

 

[72bluNblu]

If the plan is to eventually run a stereo, AC and a standalone electric fan with enough CFM to cool your car you'll probably need something in that 90-110 amp range. A decent electric fan by itself can pull 30+ amps at start up. And if the AC's going, the stereo's on and you step on the brakes and have the headlights on you're pulling some serious juice.

I run a 100 amp alternator on my Duster with dual electric fans from a Ford Contour doing all my cooling. The stock wiring, if it's in good shape, can hold up to that for awhile. But long term using one of @crackedback 's alternator wire arounds and bypassing the stock amp gauge or replacing it with a voltmeter would be the smart thing to do. I ran the stock wiring for a couple years without melting down my bulkhead connector, but I installed crackedback's wire around a couple years ago and recently did the full MAD style bypass and replaced the amp gauge with a voltmeter.

 

[67Dart273]

There is ZERO chance I'd run over about 50A on factory wiring and even then only "if" it's in good shape. The dividing line FOR THE FACTORY back then (when they were new) was 65A those units got special wiring known as "fleet police taxi" which semi bypassed the troublesome bulkhead terminals.

Look up this article on the problem, and then yeah, Crackedback sells a nice kit to bypass the thing. If you do so yourself, you need to keep fuses/ breakers in mind to protect the wiring

Catalog

 

[Kolbjorn]

I think I'm gonna go with a 110 amp alt and get a wiring kit as well. Voltmeter sounds like a good idea. Thanks for the replies!

 

[crackedback]

The biggest thing with our cars is the OEM alternators suck at providing adequate power at idle/low speeds. You want something that has a decent output right out of the gate. Total amps is not as important, although, most of the higher amp units also start out with improved low end output.