Late model alternator on a 73 GTV? - Alfa Romeo Bulletin Board & Forums

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post #1 of 9 (permalink) Old 06-19-2003, 01:59 AM Thread Starter
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Question Late model alternator on a 73 GTV?

Hello everyone

After testing the alternator with my newly acquired used engine analyzer , my alternator is only generating 18 amp of power, which is way under the stated amp of the alternator (35? 40??)

How do I test on the voltage regulator? Want to check that too before cashing out for a new alternator.

If it turns out to be the alternator, I would love to put a 65 amp one from a 80 spider (so I can run some electric fan & AC later on), would that be a perfect fit? Or some modification required?

Any suggestion on how to remove the alternator? The CarDisc I have doesn't really help.

THank you!!
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post #2 of 9 (permalink) Old 06-19-2003, 02:13 AM
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Removing an alternator should be pretty straight forward. I believe there are three bolts holding it on, a pivot bolt, a bolt on the adjuster bracket and then a hold-down locking-type bolt. I'd disconnect the batt, unplug the alternator harness and then start loosening the bolts. When re-installing an alternator, I try to use a long wooden stick like an axe handle to pull the alternator tight and then wrench her down.

I have not changed an Alfa alternator, but I've replaced them in Hondas, Toyotas, a Pontiac, a Buick and a Chevy. They were all pretty much the same as far as removal and installation.

Speaking of engine analyzers, thanks to your previous thread I started searching eBay. I picked up a new Craftsman unit for twenty bones! I have yet to break it out and play around with it. Well actually I did play with it once. I clipped one lead to my tongue but got no results on the meter.

Kai Schorr
105.36 : 1967 Giulia Sprint GT Veloce
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post #3 of 9 (permalink) Old 06-19-2003, 03:23 AM
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Hey Alfa_Chan:

Don't know about swaping between years on the alternator. I would think it would be identical as far as fit. I know 84 and 78 have the same bracket and shoulder bolt assembly. Later alternators had internal regulators so you would need to remove the old if you go this route.

When you take your old alternator to the rebuild shop, take your voltage regulator as well. Any good alternator rebuilder will be able to bench test your voltage regulator and they can also build up your stock alternator to put out more amps.

Best Regards,
John M
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post #4 of 9 (permalink) Old 06-19-2003, 05:21 AM
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You might consider going even later than '80 for your replacement alternator. On the Challenge car, I wanted to clean up the underhood appearence a little, and found out that the last series of Spiders used an alternator with an internal regulator.

Drop in installation, very easy.

I'm assuming you have the battery in it's stock location, as well as the fan shroud, so replacing the alternator does not appear that easy, but fear not...

Take out the battery, and its tray (if you can), and you'll see quite a bit more of the alternator.

The hard part will be holding the front of the main support bolt while not removing the shroud- try to be creative- its a 19mm or 3/4" head. Once you have the rear nut loose, then go after the top support system- they are all 13mm nuts/bolts.

Then remove the belt, finish removing the bottom bolt, and carefully work the alternator out.

Installation is reverse of removal.

As for the "upgrade"- if you go with the internal regulated alternator, all you need to do is keep the green wire that goes in and out of the regulator- this "powers" the idiot light on the dash. Connect the large red wire to the correct post, plug the gree wire in, and you are done.

So far, the alternator seems quite good, as we heat soak it much harder than a normal car (the turbo sits right over it...).

Good luck!!
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post #5 of 9 (permalink) Old 06-19-2003, 01:21 PM Thread Starter
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Thank you everyone.

I think I will try to find a place where I can upgrade my existing alternator before taking things apart.

Kai, you got a great deal! I was impatient and bid on the closest ending date one, I paid $20 for a used unknown brand one, and it took 2 weeks to get to my home.

Just went to Sears in Burbank last week (father's day sale), and saw the Engine Analyzer IN STOCK and on sale!
Going to get a timing light, but the price really scared me - $100??
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post #6 of 9 (permalink) Old 06-19-2003, 03:21 PM
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Eric's post is pretty comprehensive. You might want to consider this advice that was given on the alfadigest:

(Credit to Dean of Florida on the Alfa digest for this, I hope he doesn't mind me reposting it)

"The alternator (70 - 75 amp) from a '90 - '94 Spider will bolt on to your
'81. I've used that unit on both my '74 and '87 Spider's without
trouble. Of course the biggest improvement came on the '74, as it
originally had a 35 amp unit. Now I can use the H4 high beams, defroster fan, wipers, and the stereo all at once. I had one tiny problem on both cars, though, which was easy to remedy. The fan on the new alternator (at
least on both of mine) was ever-so-slightly larger than the original, so it rubbed (barely) on the washer under the head of the main mounting bolt, and also slightly on the bottom edge of the adjustment bracket. A little filing, of the washer and the bracket fixed things right up.

Besides the extra current output, the other difference is that the new alternator has its voltage regulator built-in. For the new alternator wiring, first remove the old regulator and the harness that connected it to the old alternator. Keep them or trash them, but they don't need to be on the car any longer. There will be one wire (green) left unattached in the car's harness, which is for the alternator light. Run a green 14 ga. jumper from it to terminal 'D+' on the new alternator. Finally, run a red
8ga. wire from the 'B+' on the alternator to the '+' side of the battery, using ring connectors on both ends. Since your battery is in the trunk, run the wire along the rear edge of the chassis crossmember to the big '+' terminal on the starter. My '87 has a junction on the left inner fender, where all the high-current 12V+ leads converge, but I don't think your '81 has that. If it does, use that as the termination point of your alternator's B+ wire. The reason for the new, larger wire is two-fold. First, you've got more current, so you need more wire. Second, the original wire always was too small, and by now, it's probably corroded.

Also, I should tell you that others have used GM/Delco, Ford, or Chrysler alternators of various current output, which are usually available for less than $50. Some minor machining is usually necessary, and I didn't know if that was an option for you. I prefer to stay with a Bosch, anyway, as it's 100% bolt-on, and it looks original.

Here's a source for the alternator:

$83, including core charge, and a 3-year warranty. Don't forget to
disconnect the ground wire from your battery before doing anything, and ask if you have any questions.


Lutz, FL"
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post #7 of 9 (permalink) Old 06-19-2003, 04:39 PM Thread Starter
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Thank you so much NikosF!!!

I will take everything off - radiator, alternator after Fuddruckers!!

Can't wait!
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post #8 of 9 (permalink) Old 06-19-2003, 05:55 PM Thread Starter
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Bosch AL16X 65 amp is the one I'm looking for.
$233.99 from Kragen with a core charge of 61.

I have searched both 1992 and 1973, they both show AL16X as the alternator. However, 92 one listed as INTERN VOLT REG, while the 73 AL16X list EXT VOLT REG. Same price!
Should I get the one with INT Volt regulator for the same price??
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post #9 of 9 (permalink) Old 11-24-2004, 04:39 AM
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Alternator Source

If you want a reliable replacement alternator that you can pick up at any local auto parts store for ~$22 with a lifetime warranty-check this out: Look under my Spider restoration page and then select AC conversion. At $22 its a throw away item if it ever goes bad. The machining can be done easily even without a milling machine-it just takes a little more time.
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