My 1970 fleetwood with 29k miles is not charging at idle, the engine and carb is all set to factory specs, and runs perfectly, but the alternator does not charge at idle. It’s a brand new alternator, and we put a new regulator as well. Does anyone know what the stock part numbers is for the original alternator? I’m looking to put an original “delcotron†alternator from 1970 back in the car but I can’t seem to find what would be the best for the car.
Tony,
It's been a long time since I've done it but it's not that difficult to rebuild most of the things which go bad in an alternator from the 70's. When I did it the only thing which was tricky was figuring out you needed a tooth pick to keep the brushes held in until the assembly was together. If yours is original to your car you may wish to consider it. I didn't change the bearings. I suspect there's someone on the site who likely knows how to check each part... or a google search away.
Are you sure it's not charging at all? It was with an internally regulated alternator but a friend showed me a trick for knowing if the alternator is charging. If it is you can feel a magnetic pull by placing a screw driver tip close to the front snout while it's running.
Scott
Here are the stock part numbers.
Is it charging at normal speeds?
Is the Ignition Light illuminated on Start-up and run?
If the engine is idling too slow, that could be the cause of the poor performance, as it does take voltage to get an Alternator working, as against a Generator, which will charge from really low revs, and with no voltage.
Bruce. >:D
Quote from: The Tassie Devil(le) on December 31, 2020, 01:06:04 AM
If the engine is idling too slow, that could be the cause of the poor performance, as it does take voltage to get an Alternator working, as against a Generator, which will charge from really low revs, and with no voltage.
Bruce, are you not a bit confuse here? 1970 car has an alternator, the generator, which does not charge at idle, was a thing of the past.
Quote from: Roger Zimmermann on December 31, 2020, 03:33:18 AM
Bruce, are you not a bit confuse here? 1970 car has an alternator, the generator, which does not charge at idle, was a thing of the past.
No confusion at all. I was just highlighting the difference between an Alternator and a Generator in the actual charging department.
Bruce. >:D
Tony,
Do yourself a favor and pull the alternator and make a visit to your local shop that overhauls alternators/starters/etc. They will do a few simple tests in no time.....then, you'll know ex actually what the problem is. ....walt...tusla,ok
AutoZone also checks alternators, IIRC. Assuming there are none of the "old school" shops in your neck of the woods.
Hello Anthony,
Was the charging system working properly before you installed the new alternator and regulator? If not, and you suspected a bad alternator and or regulator (thus your replacement of the parts), you may want to look again at the wiring, grounds, and battery to see if any of these components is in need of maintenance.
Respectfully submitted,
Christopher Winter
the engine was detailed (repainted factory colors and cleaned) and some parts were changed out to look nicer. So my original alternator is long gone. I would like to get a factory 1970 alternator in order to have a better looking engine bay, then perform tests with that. The idle is perfect, and the GEN light does not come on while running (bulb does work) My concern is that this replacement alternator is too low of an amperage for a FWB
I have seen low alternator output caused by failure of some diodes
in the 6 diode main output rectifier. It still had some output on the
still functional diodes.
The solution at this location would be an upgrade to an internally
regulated alternator. Much simpler to maintain. Bruce Roe
Quote from: bcroe on January 05, 2021, 02:33:35 PM
I have seen low alternator output caused by failure of some diodes in the 6 diode main output rectifier. It still had some output on the
still functional diodes....
Bruce Roe
Bruce,
I had the same issue on a 1968; partial output due to a diode problem. In my case the dash light was barely lighting and coming and going as I recall but I had partial output.
Scott
All my dash lights are really dim would my alternator cause that too?
Quote from: O. Ramirez on January 09, 2021, 11:38:09 PM
All my dash lights are really dim would my alternator cause that too?
Try rotating the headlight switch knob. I think the dash light dimmer was still on the headlight switch. The knob should be rotated every now and then to clean the contacts.
Glen
Yeah I do that and it dims even more maybe it’s supposed to be that dim I just wish it was brighter. Like I can hardly see the the lighting on it at night. It would be nice if it was a little brighter
Quote from: O. Ramirez on January 10, 2021, 12:37:58 AM
Glen
Yeah I do that and it dims even more maybe it’s supposed to be that dim I just wish it was brighter. Like I can hardly see the the lighting on it at night. It would be nice if it was a little brighter
I have the same problem, old lights, old dash being looked at with old eyes I guess.
That headlight switch, that controls the brightness of the dash lights, is like $30, clean all the contacts with DeOxit.
I have a new switch in the "I'll get to it" pile. Directions for replacement are in your shop manual.
Still not bright enough? Change the dash lights to LED.
Quote from: O. Ramirez on January 09, 2021, 11:38:09 PM
All my dash lights are really dim would my alternator cause that too?
On my "new" '72 coupe, I had the same problem. It seems that the design is the culprit: I cleaned everything for the same result. Finally, I replaced all the bulbs with LED ones. I used the type 194-NWHP5 from Super Bright LEDs Inc. What a difference! They are even dimmable.
My Cadillac is a 1979 but I had instrumentation lighting issues. I was fairly certain it was burned out bulbs so when I took the dash out to do the heater core I checked everything and replaced the burned out bulbs. It looks great now.
If there's a little bit of a soft/ slow / almost like slow rolling waves type change in intensity, without touching the switch, there is a possibility it's your charging system but if they're constant but not bright enough, regardless of switch rotation, it could be ground/ contact at the bulb or burned out bulbs. I also thought about LED's but I was concerned about areas being too bright and a potential for a dimming issue. Roger mentioned he found something which dims normally. If it also provides even lighting, without noticeable bright spots, then I would stick with exactly the version he found or I would use the original type.
Scott
Scott, there is no bright spot; the illumination is what I expected. I once bought halogen bulbs type 57. What an error! Especially on newer cars, those bulbs radiate too much heat, fatal for plastic instrument clusters.
going back to the original discussion, someone recomended that I may have a bad connection somewhere, When I originally got the car back from the shop, I went to put the headlights on and nothing happened. Theres a harness that I touched on the firewall that immediately got the lights to turn on, He said it is possible theres still a bad connection so the car is not grounding properly, does anyone have a way to test this theory out?
Quote from: Tonyv_73 on January 14, 2021, 11:13:34 AM
going back to the original discussion, someone recomended that I may have a bad connection somewhere, When I originally got the car back from the shop, I went to put the headlights on and nothing happened. Theres a harness that I touched on the firewall that immediately got the lights to turn on, He said it is possible theres still a bad connection so the car is not grounding properly, does anyone have a way to test this theory out?
A general grounding test, run the engine (to get alternator output), turn on a
lot of load such as lights with high beam, heater motor, rear defroster. Check
DC voltage between alternator case, engine block, car body, and battery negative.
You should see much less than 0.1V everywhere. Typical grounds are to the car
body from along the path bat neg to block/starter, and from engine/trans bolt to
the firewall. Adding more cannot hurt.
From there, check individual device grounding to the body. Bruce Roe
Typical GM wiring scheme for that era was 3 fusible link wires from the battery terminal on the starter that feed everything. Being at the starter is close enough to the road that that area can get wet and road grime. Also means those wires have to get close to exhaust parts so easy to be damaged if the person replacing the starter doesn't take extra care to get the wires back in their original routing with original shielding.
The 3 circuits are:
1- to the headlight switch for the headlights only, all other lighting controlled by the switch gets feeds from the fuse box.
2- to the fuse box for the stuff that is always on
3- to the ignition switch and then to the fuse box for the stuff that comes on with the key.
Knowing that can really help narrow down issues especially if every system on the car doesn't seem to be effected.
The regulators take a 'reading' from somewhere in the system and its at this point that they are trying to maintain their set voltage. In the internal regulator era that I think started in 73 they more often than not just checked the voltage at the back of the alternator itself on the wire that went to the battery. External days the point was further from the battery so lot more chances of other loads and connections along the way to effect things. You also have a fair amount of wire between the regulator and alternator where there could be connections.
Quote from: TJ Hopland
The regulators take a 'reading' from somewhere in the system and its at this point that they are trying to maintain their set voltage. In the internal regulator era that I think started in 73 they more often than not just checked the voltage at the back of the alternator itself on the wire that went to the battery. External days the point was further from the battery so lot more chances of other loads and connections along the way to effect things. You also have a fair amount of wire between the regulator and alternator where there could be connections.
An external regulator takes its voltage measurement referenced to the body where
it is mounted, so a poor body ground can throw it off. Bruce Roe
so could this cause the car to run on low voltage (11.9v) when the headlights/heat/radio are on at low idle
Grab a set of jumper cables and start adding grounds in various places see if anything changes.
Here are some photos of what im dealing with, seems that the alternator isnt really doing much, this was with no accessories on. Brand new alternator brand new regulator (ive tried about 3 different regulators and 2 alternators and had the same issue) . If anyone sees anything suspect let me know. (the 13+ volts was when I was racing the engine)
Did you try adding some grounds like with a set of jumper cables while you had your meter set up like that? Try hooking both cables to a good clean spot on the engine near the alternator then put one on the neg battery and find a spot on the body for the other. As noted try the body of the regulator too. If there is no change then not likely a ground issue.