DIMMING LIGHTS---still!!!!!

[moparmac]

Upgraded alternators to the 78 amp, relayed the headlights, and the cars voltage at stopsign drops to 11volts. Is there something else wrong??? I also have the battery in the trunk and supplied diagram shows my connections. Any other suggestions before I start building a new harness???

[ehostler]

the 78 Amp alt is not strong at idle. Many of the alts had poor charge cahacteristics at idle. rebuilt alts to to have poor charge cahacteristics at idle as well.

Try an alt that is 100A or better. If you can find one, try using a smaller alt pulley, as it will make the alt spin faster at idle.

[usdart]

A loose or missing ground strap will cause this also.. I know there is one from Engine to body,passenger side rear of engine. There is also one under the steering column. Anybody else think of any???
Dave

[frederick_76]

I thought thats the way old Mopars are.

[mtrv8n]

I find that idle must be at 850-1000 rpm to keep the lights steady.
Yes, old mopars are that way, doesn't mean it has to stay that way. Powermaster has alternators that put out more amps at lower rpm's, rather than high rpm. I'm not sure if those are two wire, which is what you want for the street.

[ehostler]

Keep the powermaster crap and buy the 130 AMP MOPAR alt that keeps coming up on ebay. They have alot of them, because they are converting brand new vans into ambulances. There is a complet thread in the archives as how to do the conversion. When all is said and done, the conversion will cost no more than $150. As you have already upgraded the regulator and done the filed wiring, the upgrade should cost no more than $100.

The nice thing is that if this alt should EVER fail, you can replace it at any auto parts store, and get the exact same thing in exchange. If you try to exchange the powermaster, you will just get a normal GM alt in exchange.

[dkn1997]

Ed's got it right, if you cannot find it on ebay, try emailing the place some of us got them from:

trucknrv@truckandrv.com

or try searching ebay for seller truckandrvsupply.

for 75, you cannot beat it!!!!!!

before you go nuts, if that is a rebuilt 78 amp you got- make sure it is good. I have read in many places that the generic rebuild is inadequate at best- something about not changing everything that needs changing.......

On that powermaster, according to another guy on the board, it is not a bolt in either, he had to rig up some brackets, and still pay 200 bucks!!!

[6pakman]

ok guys heres the real deal. old mopars do that becauce over time your chassie grounding gets old and surface rust takes over and gives you a poor chassie to body ground. there is really no way to get around it except to remove all the rust and get clean metal to touch each other. yes that means a unibody restoration. lots o time and money.a better alt will help BUT, you will not get those lites to really shine like they do today.it just wont work. you can replace all the wiring in the car, that will help a bit but if those grounds do not have a solid metal serface across the car, you will STILL get the same problem.all that alternator is going to do is give you more amperage but the more you pull from it, the more resistance to ground you get.it will be very important if your running high volt ing. the best thing you can do is just run new grounds to all the voltage points in your car. direct from the battery.

[coolcarz]

Also make sure you have a good ground on your voltage regulator, where it mounts to the firewall, and the ground wires for the lights clean up those connections, and make sure you have some new halogen lights, the connection to your alt has to be correct too, look at your wiring diagram see that the alt field wires are on the right ones... I have a 65 amp alt in my 71 duster lights are good , after i cleaned the connections and replaced the lights... before that I had the same problem.. it holds around 14 volts now though... with smaller crank pulley too!!

coolcarz

[PRO]

everybody who mentioned a poor ground wins a prize!!!!! keep in mind also that an alt gauge in time may build resistance,to check simply run a 10 gauge wire from the alt "batt" terminal to the battery positive post,if your charging voltage increases then its bad,by the way what a lame diagram due to the fact theres NO voltage regulator shown!,I always run a ground from the batt neg post to the VR mounting bolt,also dim headlights can be a poor ground on the radiator support in the headlight harness(near the batt)........PRO......

[ehostler]

As the headlights are fine, when the engine is at speed, however his voltage drops to 11 volts, when at a stop sign, either the engine is idleing low, the wrong size pulley is on the alt, or the alt is unable to provide sufficient current at idle RPMs (not uncommon for a rebuilt alt).

I say that it's not uncommon for a rebuilt alt to be tha cause, as I've seen it too many times. Heck when I had to replace the Alt in my '96 Ram, the rebuilt alt has a hard time keeping up at idle. Don't tell me that it's bad grounds, as the original alt was not having this problem (until it failed that is).

[dkn1997]

I just got back from a friends house, and man, are those headlights bright!!

You gotta change out that alt!!

check out the attached pics in the tech archives of the previousely mentioned post "alternator conversion"

look at the one titled voltmeter. that says it all. 35 year old wiring, no resto done to car, and this thing puts out like the town whore!!!! that pic was taken w/car at idle, all accessories on.

[coolcarz]

So if it was the pulley size, what size would he have ... his pulley is too small... or to large? just wondering. I replaced my alt 2 pulley to a single pulley , it looks smaller then the 2 pulley , and i also have a smaller pulley on the crank, but it seems to charge fine and keeps the volts up to 14 .. but re did all the grounds also... before it was not that great.. for sure...

coolcarz

[usdart]

Pulley,SCHMULLEY. He's got a draw on his alternator to find.
Need an alternator draw test,or take out your fuses one at a time until the gauge reacts. This will tell you which component to test and investigate.
Don't take offense I didn't mean to come off harsh, but before you blame stock size pulleys I would look elsewhere.. I have a 78Amp alt on my small block Dart w/air. no problem with low charging voltage,but when you run air you need to bump the idle up to account for the extra drag on your engine. Most cars are equiped with an idle solenoid for this purpose.
I also found some wires that had been scabbed on under the dash. The previous owner fancied himself an auto electrician (I guess).
There is also an issue with wire size and age when you add more Amps. I would be very careful as your old wiring may not tolerate 130amps. FIRE>>

[Bigfoot]

Returning from work the other morning in the driving snow my lights were also flickering when I came to a stop and the discharge light came on until I pressed the gas a bit. I had the headlights on, the rear defroster on ,as well as the radio, the windshield wipers as well as the defroster. With my punny 60 amp alt. it was loaded down. I think I will also change my pulley to something a bit smaller to bring up the rpms because changing to the next size of alt. is 78 amps or so and I wouldn't think that changing to a higher amp output will make any differnce until you are off idle.

[ehostler]

Originally posted by usdart
Pulley,SCHMULLEY. He's got a draw on his alternator to find.
Need an alternator draw test,or take out your fuses one at a time until the gauge reacts. This will tell you which component to test and investigate.

Hmmm... I know for fact on multiple cars that I've dealt with, the (no longer stock) pulley was normally the problem. That was done by testing out the entire electricla system to find that there were NO mystery current draws.

Don't take offense I didn't mean to come off harsh, but before you blame stock size pulleys I would look elsewhere.. I have a 78Amp alt on my small block Dart w/air. no problem with low charging voltage,but when you run air you need to bump the idle up to account for the extra drag on your engine. Most cars are equiped with an idle solenoid for this purpose.

It is rare to find a 30+ year old car with the stock pulley still in place. It is often changed out with the alt. On many occasions you end up with the wrong size pulley. Also, like I said before, a poorly rebuilt alt, often is unable to keep up with high demands at idle. That is one other reason to go with a smaller pulley on the alt.

There is also an issue with wire size and age when you add more Amps. I would be very careful as your old wiring may not tolerate 130amps. FIRE>>

Which is why would need to read the Alternator thread in the archives, before doing an upgrade to a 130 Amp unit. It DOES mention the use/need of a 4g wire from the alt to the battery lead, on the starter relay.

And as stated by dkn, the 130A alt does an awsome job of keeping up with demand, at idle.

[dkn1997]

you tell 'em Ed!!!!!!

[turbododge]

Right on Ed. I drove these cars when they were new, and they all had dim lights at idle, unless they had the cop car option, which was a big alternater and an idle speed up solenoid (or manually operated speedup). Cleaning connections, fixing grounds, etc. is a good idea, but is not likely to fix the problem. The best solution is a better alternater, next best is to spin the one you have faster with a smaller pulley.

[usdart]

I have never had a pulley problem on an alternator. But then I probably have not changed as many as you.I don't think I will follow your good advice. I can't afford a 130amp alternator anyway. My car does just fine on my original wiring so I don't think I will change any of it yet. You guys are obviously way smarter than me so I will no longer offer my little bit of (what I thought to be) help. You are doing things at a different level(Race or Drag) than my car will ever be.
If you don't mind I would like to remain a member so that I can use your expertise as it pertains to my particular situation.
"you gotta know when to fold 'em"

If you need a friend, I can be that!

Thank you so much for all your past help you gave me,I love the site and my MOPAR>>>

[dkn1997]

ummmm........ahhhhh.....

[ehostler]

$75 for a new 130A alt isn't too expensive. That's about the cost of 2 rebuilt 40A units. They currently have 5 more of these alts up on ebay. They've been selling alot of them, since the alternator conversion thread (now in the archives) first started.

If my car were strip only, I wouldn't care about a charging issue. My car is mostly street driven. It sure would be nice to not watch the headlights dim at every stop light/sign.

Everybodies views and opinions are always welcomed. It's just that many of us have had experiences contrary to yours. If your charging system works great and the headlights don't dim (when sitting a stop sign, with your foot on the brake, and still in 'D') then you have the rare exception and should be proud of that fact.

[usdart]

I just put a new 78 amp on for $34.00. My car is my transportation to and from work. I am trying to slowly make it look and drive better. It does turn heads now and I get an occasional thumbs up (I think it is a thumb). If it does dim at a stop I haven't noticed it since the Battery and Alternator change, and all the little cobbled together electrical issues I have resolved over time.
I turned EVERY bolt myself,mistakes are made and I pay for them but it is MY car. I am very proud of my little A body because I raised it from a Six to an eight w/disc brakes,bucket seats,console,Rallies,and every part under the hood is new down to the washer bottle. Much more to do but then that's what a hobby is ..
I would really like more HP but budget won't allow it (YET). My little 318 with edelbrock intake and carb will have to do for a while.
Now you probably know more than you wanted to but I like to brag on my old Dart..

[ehostler]

I never used to give the little 318 alot of credit. Then I saw what cuda66273 has done to his. OK, so it's not really streetable but, he's got that 318 running in the 12s and hopes to have it into the 11s next season.

Most of us have broken a knuckle or two, working on our beasts. That's the only real way to appreciate the car. OK, so we've cussed at them and kicked their tires, as well... LOL

[BILL THOMPSON]

The wiring should go battery to master cut off then out to the car use at least a 2 gauge wire from the battery to the master cut off then 2 gauge(min) to the starter sol a large charge wire 4 gauge
at least + 2 gauge to the starter your loss is probably in the wire we run a 78 amp on our car + have no problem running the motor fan inside fan fuel pump and the electronic ign if you have more than that I would install a newer bosch or nippondenso they will work with only minor mods to your brakets + spacers + go up to 120 amp but if you have the basics you should be fine with the 78 amp.full feild the alt to see if it's working(start the car disconnect the regulator(important to have a volt meter hooked to the battery get someone to watch the voltage while you ground the green wire with a test lead if the voltage heads for 15 + volts the alt O.K and you could try a regulator make sure you don't leave the test lead on to long as it can cause damage also check your ground on your regulator housing.)

[darren509]

Sorry to but in guys, but on a 71 car with after market elec. ign., does my voltage regulator need to have a good ground also ? Kind of a sloopy fit now.

[ehostler]

The regulator should have a good ground, regardless of year or ignition system.

[superdart]

Originally posted by Bigfoot
I think I will also change my pulley to something a bit smaller to bring up the rpms because changing to the next size of alt. is 78 amps or so and I wouldn't think that changing to a higher amp output will make any differnce until you are off idle.

Actually a higher amp alt will make ALL the difference in the world at idle. I have installed a 100 amp alt in my Dart. I had to disconnect my factory amp guage because my new ALT charges at 40 amps AT IDLE, which is higher than my amp guage goes MAX. I have a Mopar (MSD) BLaster II coil, electric fuel pump, and I'll be putting electric cooling fans on it. I had my ALT rebuilt at a local shop for only $100. and it works great.

[barracudadave67]

Check out this site for electrical info on aging cars. get your lights brighter and get rid of your amp gage.

www.madelectrical.com/index.shtml

it sounds good to me
B.C.D.67

[plydus340]

I had a 70 sport fury with the same problem. Try checking the voltage regulator. Good luck!

[timty2]

Working though this same problem myself on various mopars (72, 68 and 69) I found most aftermarket alternators were very weak. Even purchansing chrome high buck units or having them rebuilt at various shops did not solve my problems or made them worse!

After I worked out various grounding issues (In each case, this was a gradual improvement, one connection at a time). I also found the alternators from NAPA were inexpensive and worked outstanding at idle! This includes both single and dual field alternator styles.

While I agree those 130 amp alternators are probably the best solution, the output of the EXISTING alternator, regulator, and all the gounds as well as the contact resistance at the fire-wall bulkhead connections must be checked before changing anything else.

If the regulator mounting screws are stripped, run a ground test wire from the alternator case to the regulator case and test the output again. In addition, verify the battery ground is a low resistance connection to both the block and chassis... and make sure the ground strap is intact from the chassis to the block. (Each must have connections clean from oil, acid deposits, rust, etc...)

I would recommend making sure every basic issue checks out before throwing different pully sizes or high current alternators at this problem! It is too soon for that becasue you have not isolated the problem yet!