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I need a larger Alternator. 1-Wire only way to go?

70_Fastback

70_Fastback

Hell Bent for Speed
My stock alternator (55 amp ... ?) is not cutting it, nor keeping up. I notice my volt meter dropping ever so slightly the more I drive it.

I see a drop in the gauge when the E fan kicks on. And even more so in the evening when in conjunction with the fan on, turning on the headlights drops it too.

Is there a stock type, high ampacity alternator that has exterior regulation as a direct replacement to the OEM alternator, or is my only alternative to swap to a 1-wire style alternator with internal regulation?

If I have to change, what wiring modifications will be required to go from exterior regulation to integral regulation?

Any specific ampacity suggested? 100? 160?
 
I'm by no means an expert on charging and electrical systems. I'll rely on Midlife when I need him, or hope he'll be there with some advice. I bought a Chrome 100amp internal regulator alternator a while back. About 150 bucks worth! I figured I'd need higher output due to running halogen headlights, single or dual electric fans, maybe even electric windows(I said maybe!). But Bruce at Surefire Restoration here in Houston(I'd like to consider him a friend, he has helped me so often with restoration tips), he said I didn't need 100 amps, he even kind of laughed that I had bought such an alternator! He told me to run the highest output alternator (60+) with the standard external v-regulator, and that should be just fine. I was worried about having to modify the wiring, that's when he said just use the stock stuff and that will be just fine, afterall that's what's been used for a long time and has been proven to be ok. He put it better than the way I worded it. So I bought a stock alternator as above and the stock v regulator(I love the way it looks on my radiator support~like it's supposed to be there! Well that's about all I can say~ If an argument should arise, I'd have to call Bruce to defend me! :doh
 
The stock is ok until you add non stock/original windows, cooling fans, and other high demand items. The cooling fans themselves draw a pretty high load upon startup. I would say you would want to look at the load possibilities and use the correct unit. If the stock still fits the demand, good. If not, upgrade.
 
Reading your post on another forum, you definitely have a bad Voltage Regulator, as your battery is not being charged. The 65 amp alternator should be fine, so long as your electric fan is run via relays directly from the battery (and not the underdash fuse box). The only time you should see a higher need for amperes than 65 is when your fan kicks on (transient load upon starting the fan), in which case your battery should easily cover the extra load.

If you find your volt meter reading lower than normal when the fan is running vice when it is not, then upgrade to 100 amp alternator.

Whenever one upgrades an alternator, never assume that the existing wiring is sufficient to handle the extra loads. The upgraded alternator is for non-stock accessories, and they should be wired directly from the battery with its own circuitry. Current loads are determined by the draw of the various components: you can't shove more amperes down a wire than what is needed.
 
I went ahead and ordered a new 100-Amp, exterior regulated alternator. I will go a head and buy another regulator as well. This one is a brand new one though. And just an FYI, the ignition system, fan & headlights all come direct from the battery now and are controlled via relays from the ignition switch.

I tested the voltage output from the alternator last night - direct from the BAT terminal on the back and it read 1.3 volts at idle and 3.0 volts at varying higher RPMs. I was working the throttle so I couldn not see the tach. But when I was talking to Sluggo, he noted that I need to bring the alternator into full field to test it corecctly. I guess that I did not do. Is the correct way to jump the 2 teminals as stated in the other post Mid? Then read the voltage?

I actually unplugged the first harness, connected from the alternator, when I did my read directly from the alt.
 
Someting's not right...you should see 13.5-14.5V at idle, and with the engine running with higher RPM's, the voltage should be at the higher range. 1.3 and 3.0 V seems very very wrong.

Are those numbers typo's and should be 13.0 and 30.0V (without and with the bridged wire)? If so, then the alternator is probably OK.
 
Not typos Mid. And likei said, that was NOT bridged or jumpered. And it was 1.3V @ idle. Do I need to jump it to full field it to get an accurate reading?

thanks
 
You had one probe on the BATT terminal of the alternator, the car was running (idle), and the other probe on a good grounding point? Something is still wrong, as the BATT terminal of the alternator should be connected to the positive post of the battery via the starter solenoid.

By jumpering the A to F plug on the disconnected voltage regulator plug, you're essentially fooling the alternator to output all available voltage to the battery (without being regulated). If you've done exactly that, and the alternator is only putting out 3.0 V, your alternator is one bad puppy.
 
That 1.3V reading was with the alternator completly disconnected from all systems. A stand alone reading.
 
Oh. The test has to be done with the engine running, but the VR plug disconnected.
 
And it was was running. The alternator was spinning via the belt, just not connected electrically to the car wiring.
 
Well then, I would strongly suspect your alternator is bad, probably the diode pack.
 
Sorry to beat a dead horse... BUT, if I'm understanding you correctly, even with the voltage regulator unplugged and the engine idling - the alt should have been putting out more than 1.3Volts at idle?
 
Yeah...it should be putting out something on the order of 18 volts!
 
Ah, ok. so that makes me *hope* that my voltage regulator is good then & I just had a faulty alternator.

The new alt should be here mid week - so I'll get it changed then and report back.


:pop
 
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