Alternator/Headlight Upgrade

[Jeff Pozorski]

I have followed the threads regarding replacing the stock alternator with the 7127 model, but I don't recall reading if the 7127 will work in the Manta. Has anyone tried it? It must be an easier install as the Manta engine compartment is much larger to work in than the GT.

[oldopelguy]

Works great in the Manta.

[kmon]

Hi everyone, I was just curious if i could use a large gm alt instead of the delco style. The pictures from a few of the installs look pretty tight with even the smaller style. How much larger are the late model alternators, I havent been able to find a side by side comparison anywhere. Thanks for the help.

[houserc]

I would tell you to go to your local auto parts store and look at them both side by side. The parts guy I talked to was more than happy to help me out with this. Any model larger than the "7127" Delco-Remy 63 amp alternator from NAPA will have a difficult time fitting effortlessly into the area.

You can read one of the posts earlier of an install with a larger alternator, but check out the sizes as they come out of the box. Anything larger than the 63 amps will have a larger housing.

To install and remove my alternator, I have to either rotate the distributor or remove it. That depends on how your distributer was installed in the lower cog during assembly. My engine has been overhauled and the mechanic had the cog rotated one tooth that made it difficult to install or remove the alternator. The difference in the Opel Alternator and the GM is the mounting brackets are offset on the opel and the GM is 180 degrees out, top and bottom.

Do you need more than 63 amps? What would you be running? (Or is this a Tim "the toolman" guy thing?)

[jimsky]

I agree. I was just able to get the Delco 63 amp alternator installed if I removed the coil & holddown bracket. There was only one orientation of the alternator that would allow it to slide down into position. I had no desire to remove the distributor.

The 63 amp alternator is more than enough for me. Bright headlights, fast spinning blower motor...even at the same time! I've installed a decent 4 speaker stereo, and an electric cooling fan. The Delco has done just fine, and you can't beat the price.

[kmon]

Well, I have a few projects that are going to suck a lot of power. Dont give me too much flak, but I'm planning on doing carputer install with a touchscreen in the dash. That alone draws over 20 amps. I would also like the overhead for a nice stereo (probably do that later down the road, when the gt fund is looking healthy again).

Great idea houserc, I'm going to run down the parts store possible tommorow to check out the difference. In the mean time, how much clearance do you have around your new gm alts. I really dont care how much i have to tear apart to get it in as long as it fits (no cutting on the car!)...Also, I should be going with a dis ignition with the new engine so thats gives some more room.

[houserc]

Look at the picture Jimsky posted in the sixth entry of this thread. See if you can print that off full size and look at the same area of your GT to compare.

The alternator is pretty close to the wheel well area. I dropped mine over a little more to have a different top mounting bracket.

Two things to look at involve geometry of the setup;
The top mounting bracket comes up right under the distributor. So, an alternator much larger will require, possibly, some fabrication of the top mount.
The top mount of the alternator will get out of sight of the top mounting bracket pretty quickly with the angles and position you set it all up at.

Let us know how you come along with it.

[garrymc]

Originally Posted by Washout Thanks to all who contributed to this thread. I went to Autozone this morning and with a list of parts from here I bought everything I needed for the conversion. One trip, got everything, it took me about 2 hours for the complete job, start to finish. Everything worked just as advertised! Grand total for the whole job was $80.20. That's pretty cheap for such a big upgrade. Thanks again guys, this is one heck of a site.

Hi Washout,

Do you have the Autozone part number handy ? Could you give us a run down the parts you got there ?

Garry

[houserc]

Entry 26 give a quick list of what is needed along with a couple of other entries.

All you have to do for the alternator is as for the GM alternator of 7126. It's a standard GM alternator.

Good luck. You'll enjoy the upgrade

[kmon]

Just to let you guys know, I checked the dimensions between the small and large style gm cases. They seem to be pretty close, circumference of roughly 19" vs 21", depth of the larger case is slightly longer but that shouldnt matter. The mouting holes are almost the same distance apart as well, I think im going to go ahead and order the larger case and install it sometime over the next 2 months, more news on progress as it happens.

[jordan]

jimsky, I did the conversion about the same way you did, copper bushing in the alternator witht he OEM bottom bracket and the autozone top bracket. the only problem is the top bracket rubs on the distributor, did you bend yours the same way the stock bracket was or just use spacers? also does the red wire from the pig tail go to the field stud along with the field wire? and the white wire from the pig tail go to the blue/white from the idiot light?

[soybean]

I too went to a GM alternator as others here have done which has worked so far. The way I mounted mine was, I took the original lower bracket off to use as the pattern. On the new alternator, I put a piece of duct tape on one end, mixed up a batch of JB weld, poured and dabbed it in with a piece of wire until it was full, put another piece of duct tape over the open end and let it set up,(couple of days). Then put the bracket and alternator onto the drill press and drilled out the hole the original bracket size was. Upon assembly I put two washers in the back to make up for the length difference.
On the top assembly since the rubber bushing was gone, I drilled a chrome universal bracket to fit the hole size of the end of the original metal part of bushing and spaced out the area where the rubber was. The bracket was about a quarter inch away from the distributor and the belt is even. The belt was a Dayco 15358. The last photo is one I found someone else had done modifying the upper bracket It was in my Alternator file. Don't know who to give credit to. Very nice.Also the fourth picture is not mine, I think its jimskys.
The Red wire is jumped to the battery terminal. Really needs to go to a terminal block with a fusible link installed, then to battery.
The original Opel wire is attached to the Battery terminal.
The white wire is attached Blue/ wht wire for the idiot light. Another good thread here in the forums in charging. Everything needs to be on fusible links. You don't want to burn up fuse box. I'm in the process of going through the wiring in the front of the car while the engine is out and upgrading it, and running the headlights through relays off an aftermarket terminal block and using the original wires to power the relays. I figure between the fuse at the block, and a fusible link from terminal block to headlights should protect everything. Pardon my long litany. Jarrell

[jordan]

Well it's in and working as far as I know, the headlights are brighter but when I turn on the headlights and the stereo is on the stereo goes off momentarily from the new needed surge of electricity, is this normal?

[greensmurf20]

jordan: my sterio did the same thing in my first GT. it was a Pioneer CD deck, ended up being a bad ground to the deck its self. i had stock alternator, only reading this thread as i plan on the GM alt this winter. altho we had different alts i think my problem may be relevant to yours.

[GT-Freak]

I just did an alternator swap yesterday. It really cleans up the engine compartment, no external regulator and wires. Looks great. It cost me $63 total. I used the stock lower bracket because it sets the alternator lower than the Chevy bracket (more room), plus it's stronger. WOW. Lights. This is a huge improvement.

What I did:
- Used a drum sander to remove material on top of stock bracket at the front alternator bolt hole (about .070").
- Sleeved the Delco alternator with 3/8" tube and used the stock bolt.
- My Delco alternator came with a plastic fan. So I used the drum sander to trim .060" off the perimeter of the fan. (Hold the fan longitudinal with the drum axis.)
- Used two 5/16" washers (about 0.1" total thickness) in front of the alternator to space it back for proper belt alignment. Used one washer in back to fill the gap.
- Rotated the back of the alternator 90 degrees to make the plug vertical. (They come stock in 3 o'clock or 9 o'clock.)
- Attached the ground wire to a housing bolt on the alternator. The Delco ground bolt is big and would require a new end that I didn't have.
- Modified a Mr. Gasket pre-'69 Chevy upper alternator bracket like other posts. I have a 10# BFH and 10" 50# BF vise for making the bends, which helped. I drilled a small hole vs. the about 5/8" hole to fit the stock nuts/washers. Then used a regular nut against the block (see ground wire below) and stock outer nut flipped backwards for more belt clearance. I made the bracket longer than stock (1/2" from brake stinger housing), as there's plenty of room and it's easier to get the longer belt on. It also made the bracket slot center over the alternator, which is ideal.
- The coil must be removed for installation. And the distributor loosened to rotate the vacuum advance out of the way. I marked the dizzy placement in advance.
- Wiring is straightforward as posted before.

What I'd do differently:
- Use a Chevy size lower bolt (3/8" dia.)
- I'd make offset washers from round aluminum bar stock (about 3/4" dia. x 3/4" long) to replace the stock rubber spacers. Drill Chevy size bolt holes in the washers with minimal edge distance. Epoxy them in, hole to high side, located front-to-back to properly place the alternator. And probably pin them also. This way there's no grinding on parts, no using washers and sleeves, no locating special fans, just bolt in a stock Delco alternator.
- Make a REAL ground wire and fasten it to the big ground bolt on the alternator. The stock wire is a JOKE. The 63 amp alternator may make up to 75 amps. How is 75 amps going thru that little end on the stock ground? This is why I used a nut between the upper bracket and block.
- I'd run the red pigtail wire (voltage signal) back to the fuse box.
- Everything else I'd do the same.

Hope this helps someone.

[markandson]

I followed the advice of this thread a bought a Delco 7127 63amp alternator. I also use the universal GM alternator bracket that looks like an "F". What I did differently than everyone else was the upper bracket. I used half of the stock bracket and half of the GM universal upper bracket for small block chevys. I cut 4 notches in the GM bracket and bent it into a smaller radius, it was shortened as well and then welded the the first half of the stock bracket. If I had it to do over again, and I might, I would cut more notches and bend the bracket even further so it would not rise up next to the distributor.

[guyopel]

Hi I am in the process of posting a new & better alt. choice using a GM
"CS" 105 amp alternator the case is smaller than the org. Opel alt.
( 135 mm dia. for Opel and 120 mm dia. for GM ) I have installed this with a
Chevy alt. bottom bracket and using the stock opel bracket . This is a one wire hookup and the charging light in the Opel is still used. The "CS" 105 alt.
is a better charging alt. at idle than the "SI" 63amp alt. and can respond to high amp. draws in traffic or poor weather I.E. wipers, coolant fan ,headlights, radio or etc. on at the same and at low speed . I have many photos to resize and do the write up to cover all questions and see if there is any interest.Hope this helps on your upgrades. Guyopel

[markandson]

Bummer , I would have done the better one. How much does the new one cost?

[guyopel]

The one I installed was a rebuilt unit and parts ( bracket , alt.plug )
was about $100 to $120.Guyopel

[wildone1]

Have any of you tried the one wire alt from jc whitney it just has one wire to the battery used one in my 69 worked real well

[pvcar]

well there are many alternators out there that use only one or two wires ur main battery wire and an exciter wire and the ground usally runs thru the main mounting bracket. theres a nice 80 amp one ive seen used to use on the 70's early 80's chevy trucks and then the current one they use know forget the amprage but they use it on the later 80's model chevys works pretty good and is the same size as the gm alt. i put on my gt, pretty easy to install as well, only had to modify the lower bushings, just look around and make sure u get one that has the right upper mounting locatin for your adjusting bracket.

[namba209]

From one of my maintenance manuals for the later GM products, late 80s and up, it says the alternators that have riveted case halves are lower than 100 amp ratings and the ones with bolts holding the case halves together are greater than 100 amps. But then if you get a reconditioned or rebuilt alternator, all bets are off.

[namba209]

A quick and dirty way to find out the amps is to check with your local auto parts store, there are usually 2-3 different alternators that will fit a car, so it should fair easy to look for the part/model number when you're out at the recyclers. HTH.

[maglinjosvinn]

would anyone care to elaborate on the 'bypassing the amp guage' comments. i trully don't follow. i got hte 7127 ac delco alternator and the pigtail that goes with it. i'm going to go ahead and mount the monstrosity in the car, regardless. slightly nervous about damaging what i consider 'priceless' (snicker) equipment by totally foobaring it.

and correct me if i'm wrong here plz.

Large stud on back of alternator -> stud on starter where battery connects.

run a ground wire from back of alternator to block or whatever...

Red wire on pigtail loops back to the stud.

white wire gets spliced wit hthe blue white stock wire runnning to the amp guage light.

which reminds me. HOW hehe... does connecting the alt to the trouble lamp also 'excite' the alternator?
...
and why would having the amp guage included in teh circle cause an issue. i just couldn't make sense of that site. (isn't exactly car savvy)

[markandson]

If I remember correctly it is the red wire that loops, as you describe it, that excites the fields within the alternator. The trouble light connection is just a bonus, you don't really need it to have the system work. It's been awhile since I read all the stuff you are reading, but I believe this to be correct. The thing about having the Amp gauge in the circuit is that when you kick up the amperage capability of the whole system and then don't fuse it, but run a relatively long wire through the dash, there is a possibility of overload and fire.