So my understanding is that on a 914-6, the original alternator does not have a voltage regulator on the alternator but instead, the VR is on the circuit board in the 2.5" tall rectangular tin enclosure.

The 911 engines have an integrated VR on their alternators, I believe.

So when you go to replace an alternator on a -6 and all you can find is one for a 911 with an integrated VR, how is the wiring different? What happens at the circuit board?

The notes on Pelican regarding their alternators just says "some wiring mods may be necessary", which is kinda vague.

any thoughts?

only the later 911's have an internal voltage regulator
I'm pretty sure the 3.2's do... I'm not sure what year it changed though

I know the mid 70's 911's also had an external regulator like a 914 or like a stock 914 wiring harness has

I think the 911 changed to the internal VR around the 75 models...that's when the size of the alt changed...so the 75 up would have internal VR
you may find some info on the 911 Registry site.... as brant mentioned the early 911 were just like the 914 with an external VR and many have hot rodded their early 911 to 3.0 3.2 and above and have done the electrical conversion...

CORRECTION:

From the Bird...
http://www.pelicanparts.com/techarticles/1...Replacement.htm

All 911s up to 1981 had external regulators and from 1982-on, the alternators had built-in ones.

This is the one on the 75' MY I remember....
Voltage Regulator - Marchal, (On Alternator)
Part #: 911-603-913-01-M120

Back in the mid 80's I bought a 74 2.7 short block and bought an alternator with an internal regulator in it. At that point I dumped the relay board and wired everything direct. Didn't need anything on the board for my six.

Sorry... didn't realize it was a real six!! You will want to leave it stock.

Yes, the -6 voltage regulator is on the relay board just like the rest of the cars.

Mark, is the regulator the same for both the 4 and the 6 cylinder cars? Sorry to hijack this thread.

Greg

Porsche didn't change to the internal regulator on the 911 models until the '82 model year. And the regulators for the early 911s ('70-'73) and the 914-6 are the same, P/N 911 603 206 02 (if they're Bosch), but the 914-4 regulators are a different part number.

Greg,
They do show different part part numbers BUT they are pretty much interchangeable. Now the only Bosch regulator available is one one for the 911 but it shows to work for the 914 too.

Larry is correct...

From the Bird...
http://www.pelicanparts.com/techarticles/1...Replacement.htm

All 911s up to 1981 had external regulators and from 1982-on, the alternators had built-in ones.

This is the one on the 75' MY I remember...it was a Marchal alternator with a regulator attached to it.
Voltage Regulator - Marchal, (On Alternator)
Part #: 911-603-913-01-M120

Does anyone know if there is a problem running the internal regulator with the original external? I would guess that it would not hurt a thing.

I thought the internal reg started with the mid year 2.7. My 77 2.7 has an int-reg alt.
when i bought it. Here's some alt info. You can run the int-reg on the earlier cars but the rear air deflector needs to be modified to fit over the reg.

I went back to the ext-reg as it's a real pain in the rear to change the alt in a 914-6.

this may help -

beware - there are some incorrect "upgrade" wiring diagrams out there - i learned it THE HARD WAY - had to R&R the alternator a second time due to wrong diagram supplied by vendor with my new alternator

DO NOT try to run both the oem regulator along with the new IR setup

- if you are obsessed with the look of originality - just clip off the wires or the blades that feed it in your relay plate

(fortunately, i have a "firewall porthole", so was able to do it without totally dismantling the top of the engine)

. pictured: a new 911 Valeo on my 2.7 with webers (... have since upgraded to a 3.2 motronic)

Click to view attachment

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Thanks for the info but I believe I'm going to go with a remanufactured alternator that still uses an external voltage regulator so that all of the wiring and circuit board remains unchanged. Besides, the current wiring is sized for a 50-55 amp alternator and I've already changed to LEDs to lighten the load.