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Oldopelguy,
Early in this thread you mentioned about upgrading the alternator using GM stuff as follows:

Well, since Bob brought up alternators....
I just borrowed a friends digital camera and I am taking some pictures of a simple way I use to back-fit Opel motors with a 60, 85, or even 140 amp GM alternator. I've even got the wiring figured out so the charge light on the dash will still work. I'll get the picture and some detailed drawings posted when I get them worked out enough to be presentable and double-check the parts fit into a GT. (What works in my Kadett or Manta only sometimes fits into a GT.)

I'd be very intrested in you sharing any info that you have on this upgrade. I want to upgrade my GT alternator and from what I've found out the GM Delco 10si style alternator is a great way to go. Internal regulator, good output even at low idle speed, well designed and cheap too. How did you do it? I'm all ears.
 

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Discussion Starter #2
Awesome! Whatever details you can provide about your upgrade will be appreciated. Alternator part number, digital photos of the installation, mounting bracket mods, wiring hookup...whatever you can provide would be great. I want to upgrade my GT's alternator before I consider replacing the belt driven cooling fan with an electric cooling fan. Thanks!
 

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I ordered part # 17294 (100 amp powermaster chrome alternator) from www.srbymichael.com (uninstalled)
Kudos to Bob Legere for determining how to get the idiot light to work with a 1 wire alternator . Per his post "On the side of the one-wire alternator you will notice a black plug cover. Remove the cover and you will see two terminals. The terminal that is closest to the battery terminal is the #1 terminal. Simpy run the wire from the light to the #1 terminal on the alternator. That's it!"


I also bought a ultima #01-0043 (65 amp rebuilt alternator) from O'Reilly's for $37, plus a $10 core charge. Instead of grinding on the housing to fit on the stock bracket, I had a pair of aluminum bushings drilled with an offset hole. So far no problem has evidenced itself by using that bushing instead of rubber.

I think you can just look for a GM 7128 alternator.
 

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Discussion Starter #4
Excellent. Thanks for the information. I'm off in quest of an alternator. Too bad about your GT there. Do you have plans to get it back on the road? I've heard that this is a "universal alternator mounting bracket" available. Anyone out there have a website address for this item? Thanks again.
 

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my method

While the Opel alternator bracket can be made to work, it works best with an offset bushing in place of the rubber one. I have in the past used aluminum, steel, teflon, poly, and JB-weld to fabricate the offset bushing, and surprisingly all worked about the same. (JB-weld needed an inner bushing from the hardware store.) The bushing should be made to accept the slightly larger GM alternator bolt.

The last 2 installs I have done have been slightly different. I have used the $12 chrome alternator mounting bracket from Autodrone, or any other local parts place, instead of the Opel unit. This is the one shaped like an "F" in cross-section and mounting with 2 bolt holes. The holes aren't exactly the right distance apart, but 5 minutes with a rat-tail file to enlongate the holes towards each other solves that problem. The front hole will get close to the rear mounting tab, and require using an allen headed bolt, but all the bolts on my engines have already been swapped to allen anyway, so no biggie. This will firmly mount the lower "main" tab of the alternator.

The upper tab of the alternator is slightly more difficult. Opel alternators have their mounting tabs set at @ 150 degrees apart, and GM alternators are straight across from each other. The Opel adjuster simply isn't long enough to reach the GM alternator's adjustment tab and will have to be replaced. The difficulty with that is the arc for the adjuster needs to be pretty severe to clear the alternator's fan. Chrysler vehicles with the slant-6 have an adjuster that works fine, and is easy to find in almost any junk yard. Get one of these, mount your alternator and call it a day. You may find that you need a slightly longer belt, too.

Alternately, and how I do it now, you can get the universal chrome adjuster that was hanging next to the alternator mounting braket and adjust it to work. It is @5" too long, so a new hole will have to be drilled farther from the non sliding end than the origional and the excess cut off. Now the braket will fit, but the arc won't clear the fan properly. Now is the only difficult step: Remove the fan and pulley from the alternator and replace the fan with one from a late-model smaller GM alternator. (The fan I use is from the alternator fitted in the '89 Cavalier and the like.) Lots of autoparts stores have extra fans and pulleys laying around that they will just give you if you ask, or you can take a 5/16 allen wrench and a 5/8 deep offset wrench with you to the junk yard and get it yourself. When I get alternators for Opels I just do the swap myself in the yard so I only have to buy the one alternator.

I would love to get some pictures for everyone, but the cord for my digital camera is MIA....

Now, the wiring:

The easiest wire to hook-up is the main wire for power output from the alternator to the rest of the car. This is the same red wire with the same lug as before but now on the new output post of the new alternator. The GM alternator has a built-in regulator, and the Opel doesn't, so the extra Opel one has to go. Remove it and the 3 wire harness from it to the old alternator, carefully cutting the one remaining wire to the regulator from the cars harness, leaving as much as possible in the car. Typically this is a light blue wire with a white stripe, and it is from the "idiot light" in the dash. Your new alternator has 2 spade terminals in the side near the back. I have no idea what colors you will end-up with for the mating plug for these terminals, but if you get the $4 new replacement plug at the auto store they will be red and white. Looking at the alternator from the back, the terminal on the left should be labeled (1) and the wire *should* be white. The right terminal should be labeled (2) and *should* be a red wire.
-Terminal 1 (the left one, should be a white wire) is for the idiot light and "turns-on" the voltage regulator, and that wire is to be connected to the blue/white wire from the GT.
-Terminal 2 (the right one, should be red) is where the alternator field gets it's power. This wire needs to be connected to somewhere where there is always going to be power, like the output terminal of the alternator. (When the alternator isn't spinning there is power on this terminal from the battery and when it is spinning there is power there from the alternator.) Put a nice big terminal lug on there and attach it to the output post with the other big red wire.

Now, assuming you mounted the alternator securely and wired it as above, the car *should* operate exactly as before, with brighter lights, easier starts, and wipers that work when the headlights and fan are on.
 

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Discussion Starter #6 (Edited by Moderator)
Well just got back from a test drive of my GT with upgraded alternator. I really didn't know the dash lights and directionals were suppose to be that bright! The headlights are brighter too. Excellent, I'm very happy with the results.

I ended up using a "7127" Delco-Remy 63 amp alternator form NAPA, their p/n is 213-4011B. Cost was $33.99 with an $11.00 core charge.

I used the Opel OEM bottom bracket and a universal chrome top bracket. The fan on the 7127 will interfere with the Opel OEM bottom bracket so I just ground the offending spot off with a grinder and took the highest points off the fan with a dremel for good measure. The universal top bracket had to be cut down in lenght and needed a new mounting hole drilled in it.

Since the Opel OEM bottom bracket hinge slot is a bit bigger than the 7127 tab that fits into it, I made up the difference with washers. Additionally the hinge bolt hole in the 7127 is a bit bigger than the Opel OEM hinge bolt I made up the difference with a thin tubular bushing.

A new $2.00 alternator pigtail connector, a couple of simple electrical connections already discussed and I was done. Now I'm ready for the electric cooling fan, and electric fuel pump.
 

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70's Opeler, back 4 more!
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I followed your lead Jimsky and went with the "7127" Delco-Remy 63 amp alternator from NAPA, (p/n is 213-4011B). I think the cost was in the $40's in my area and the core charge was about the same.

I decided to replace the lower bracket with a GM bracket. I had to drill a hole in the rear and use a rattail file to open it up to match the block hole pattern. This allowed me to use a bolt that fit the alternator, so no shims or bushings and I did not have to grind away on the fan fins or the OEM bracket. The stock fan belt worked, but I think a shorter one will do a better job.

I did have a heck of a time getting the alternator down into position. I ended up pulling the distributor in order to get enough room for the alternator to drop down in.

The only problem I am having now is the alternator is not charging.

I'm not sure if there is something I have overlooked or not hooked up correctly. The wiring was pretty straight forward and I am getting a reading on the dach gauge for negative charge or usage.

I travel, so my time to wrench is limited, but I think my first job is to make sure I have the wiring correct. After that, I am thinking of taking the alternator back to NAPA to verify the output.

Any suggestions would be greatly appreciated.
 

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Discussion Starter #8 (Edited by Moderator)
The alternator we both used is a "three wire" regulator. One of the wires is the "voltage sensing" wire. This is the input of the regulator circuit. The intent is it can be connected to an external point in the wiring harness to compensate for voltage drops across the power distribition wiring. I just hooked up this wire to the B+ terminal on the back of the alternator. If you don't connect this wire and just leave it unconnected the alternator will put out what you're telling it to put out "zero volts" or no output. Did you connect up the voltage sense wire?

I found I could take the alternator in and out if I removed the coil and it's mounting bracket. Then there is one orientation and you can get the alternator in and out.
 

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70's Opeler, back 4 more!
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Thanks for the reply, Jimsky.

I hooked the output wire up to the same terminal lug as the old alternator. I ran a jumper wire from the output lug to the Number 2 spade, or the Field.

There were two other wires connected to the old alternator. One was a ground and I connected that to the ground bolt on the new alternator. The second was the sensor and I connected it to the Number 1 spade.

What I am not sure of, and this is due to limited time and getting in a hurry, is if the old voltage regulator is removed. I am guessing that it may not be.

Again, I have to wait for Friday to get back to the garage due to travel.

Thanks again,

Chris
 

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Discussion Starter #10
The old OEM external voltage regulator has to be removed and disconnected for this upgrade. This upgraded alternator has an internal voltage regulator, the old voltage regulator is not needed.

The three wires of the alternator are as follows:

Main Alternator Output - terminal post/ring lug connection.

Two Pin "Pigtail" Connector:
#1 marked on case - Dash Charging Light Circuit
#2 marked on case - Voltage Sense/Excite Connection

And there is a ground connection, but I guess they don't count that in the "three wire" description. Just connect as the old alternator was done.

I hooked the main output connection (ring lug) right to were the old alternator connected.

I then with the help of a schematic from my trusty Opel 1973 service manual, I identifed the charging light wire and hooked that up to #1 on white plastic pigtail connector.

The last wire on the pigtail, #2 I just crimped a ring lug to it and connected it to the main alternator output terminal post.

That's it. I'd check your wiring before pulling the alternator out. Good luck!
 

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70's Opeler, back 4 more!
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I was able to work on the alternator today. I was a little concerned because all the wires were connected correctly and all looked well.

I took the alternator back to NAPA and had them test it. Turned out it was only putting out about 6 volts some of the time and 4 most of the time. The new alternator was tested prior to me taking it home and it worked fine.

BOY! What a difference in the amp gauge. I never knew the gauge could move that far over.

Also, I changed the distributor to accomodate the regular removal of the alternator. I had to move the worm gear over one cog in order to move the vacumn advance unit over to allow the alternator to move in and out.

Thanks for all.
:D
 

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Discussion Starter #12
Glad to hear it all worked out. Now you can consider those nifty upgrades that require current that the old alternator couldn't handle: brighter headlights, electric cooling fan....

Speaking about the dash mounted amp guage; check out the following link and scroll down to the article on "Bypassing and eliminating factory full flow type amp guages".

http://www.madelectrical.com/electrical-tech.shtml

My amp guage and wiring was burnt and crispy when I got my GT. Loose connection I guess. At just 25 amps of current 0.1 ohms of resistance will generate over 60 watts of heat. Try putting your hands around a 60 watt light bulb and you'll understand.

I ended up bypassing the guage much the way the article describes. I bought a cigarette lighter mounted illuminated digital voltage "guage" (about $15) to monitor the status of the electrical system. Cheap, but it's accurate, I calibrated it with my DVM.

There are some other good articles on that website worth checking out.
 

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Just finished my Chevy alt conversion. It came out looking nice and neat. But.......I wired it up as others here have done with the red from the pig tail to the output lug and the white to the Opel's blue and white that goes to the amp meter. Yes, it charges, but only after I rev it once. In other words, If I start it at idle and don't punch it past about 1500, it's not charging. After that it can go back to idle and continues to charge. Really charge, compared to the old 28 amp!

The papers that came with it mention it needs keyed voltage to the white wire also. The say it usually comes through the indicator light. I noticed that my indicator light on the gauge is out. To tell the truth, I never even noticed that there was a light! Could this be my problem? Will I hurt anything running it like this, as I am not ready to pull the whole dash out to change the bulb?

ThanX,
James
autoX next Sunday
 

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Okay, I got lots of replies that, yes, you need the bulb to excite the circuit. Now here's the question, do I have to pull the whole dash to change the bulb or is there an easier way? Can just the instrument panel be removed?
Thanks,
Jc
 

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JC;
You have to pull the dash panel, i.e., drop the steering column, etc
 

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James,

Actually, I think you can replace the charge indicator and low oil pressure bulbs without dropping the steering wheel. You still have to remove all the front screws and the inner screws at the bottom (just above the console, from the sides), and maybe the speedo cable, but then just tilt the front panel forward to get at the bulbs. If not, it isn't that much work to drop the wheel.

Let us know.
 

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Early GT Dash Removal

Jame PM'd me and mentioned that his GT didn't have the screws that I had referred to. Early models (I thought pre-1970) had various differences, including the dash. Here are a series of photos taken of the 1969 FSM providing the procedure for removing the early dash
 

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