# External vs Internal Voltage Regulator



## 68 GTO 4spd (Apr 26, 2014)

Hey all, 

I need to replace my alternator pretty soon and I was debating on switching over to a internal regulated Alt.

I'm running twin electric fans and would like to some day do a "hidden" stereo system and such, so I would like to go a little overkill on the new alternator. I would also like to keep the external voltage regulator mounted for a stock appearance even if the wires to it are just dummy wires.

Is there any reason to stay with stock vs internal? Any considerations that I should be debating? I found this link on a "kit" to install it : Reproduction Wiring Harnesses for America's Muscle Cars 
Go to "F.A.Q.s and look at *I want to install an Internal Regulated Alternator* and the then part number Part # 27555.

Or would you do the cut and hack method (only cleaner) of something like in this link : External to Internal Voltage Regulated Altenator Conversion - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Thanks for your input


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## PontiacJim (Dec 29, 2012)

*NEVER HACK & CUT!*:nono:

And that's my final answer. So you know what to do, right.:thumbsup:


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## BearGFR (Aug 25, 2008)

I did just what you're comtemplating. I kept the VR on the firewall, but I'm running a 105 amp CS130 alternator on my '69 now. It was beyond simple to do, the 'GEN' indicator light still works like it's supposed to, and unless you're really looking for the differences you won't see them. I didn't have to change out any wiring in the engine harness, either.

I converted mine when it became obvious that the factory 65 amp alternator just wasn't going to get the job done, not after adding twin electric fans that can pull 30 amps - each.

Bear


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## 68 GTO 4spd (Apr 26, 2014)

Thanks guys

For better or worse the electric fans were already in the car when I got it. They keep the car around 185 to 190 so it seems they work ok.

Bear, How exactly did you "re-wire" it to work. You have the exact setup I want to get. :thumbsup:

Also, do any other wires need to be beefed up to handle a high output Alt?

Thanks again.


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## 68 GTO 4spd (Apr 26, 2014)

Bringing this back up for a second.

I finally got around to switching out the old Alternator for a powermaster 150amp internal. Everything works very well but my autometer gauge is still only showing 14v to 14.1 with everything running (fans, lights, power amp, and msd ignition. 

Looking at the wiring only a small wire connects to the positive post on the alt and I "assume" that it eventually makes its way down to the starter and fuse panel. The only "thick" wire is run between the battery positive and the starter.

There is no direct large wire going from the alt directly to the battery. Would this be smart to run a large guage wire direct? To take advantage of the new Alt?


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## BearGFR (Aug 25, 2008)

Dang - how did I miss your question for a whole year?? Sorry about that!!!

14 to 14.1 volts is plenty. In order to charge the battery, all you need is for the alternator to put out more voltage than the battery does (this is how it "forces" energy back into the battery). That "small" wire on your alternator is probably pretty healthy, like a 10 or an 8 gauge wire. If you chase it, you'll find it gets back to the battery via the starter. I've got two wires coming off my alternator now. One is off the positive output that we just talked about, the other runs back to the old external voltage regulator connector (which I've actually jumpered around so that it doesn't actually do anything, but left installed just for looks) - from there it goes to the circuit that controls the GEN light on the instrument panel. I believe this same circuit is how the field of the alternator gets energized. The VR that is inside the alternator does its job by turning this connection on and off to control the alternator output. If you want to beef up the connection between the alternator output and the battery, the way to do it would to be replace the EXISTING output circuit with heavier gauge wire, but I'm not sure it's worth the trouble. If your battery stays up and your headlights don't gradually dim on a long drive with "everything" else running in the car, then you're getting everything you need out of it.

Bear


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