anyone know stock '68 alternator amp output
- Thread starter Dave NEO
- Start date
-
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 25,642
- Reaction score
- 12,930
slantys were.....................26
all others......................... 34.5
except HD and A/C, were ..41
and Special Equipment was 51
All tests are at 1250 rpm, and at 15 volts at the alternator stud.
This is a test point and not the maximum output.
So says the 69 FSM
I other words the output may vary with rpm,and where you measure it, and at what voltage, and maybe even on the alignment of the stars,lol
all others......................... 34.5
except HD and A/C, were ..41
and Special Equipment was 51
All tests are at 1250 rpm, and at 15 volts at the alternator stud.
This is a test point and not the maximum output.
So says the 69 FSM
I other words the output may vary with rpm,and where you measure it, and at what voltage, and maybe even on the alignment of the stars,lol
Last edited:
thnks - I wasn't very detailed - barracuda, 383 motor. Just want to eventually replace with something rated close to what original may have been rated at vs. something that a lot higher output, so looking for what they were rated at. So you are saying they were all rated at 51A or less?
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 25,642
- Reaction score
- 12,930
Per the test method, that is what the FSM says. Read it carefully.
Just bolt any round-back on,and you are golden. The regulator will take care of everything. If a dual-field alternator is used,then the second terminal is just to be grounded.
As to square-backs, anything that bolts right on will also work, but the higher output ones, IIRC have their own required regulators.
Pre-1970 alternators were single field, and used mechanical regulators. I highly recommend to get rid of that little trouble maker. The dual-field system is practically trouble free, and the retro-fit is easy. You just add one wire and a special plug for the electronic regulator;easy-peasy. Kits are available from Mopar.
Just bolt any round-back on,and you are golden. The regulator will take care of everything. If a dual-field alternator is used,then the second terminal is just to be grounded.
As to square-backs, anything that bolts right on will also work, but the higher output ones, IIRC have their own required regulators.
Pre-1970 alternators were single field, and used mechanical regulators. I highly recommend to get rid of that little trouble maker. The dual-field system is practically trouble free, and the retro-fit is easy. You just add one wire and a special plug for the electronic regulator;easy-peasy. Kits are available from Mopar.
lots of good info - thanks - was thinking of protecting old wires from too much current, though if I am not drawing a lot the system should be taxed I think.. plus if I understand you correctly, the new regulator should be helpful for this as well..
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 25,642
- Reaction score
- 12,930
IMO you should be more concerned about the connections. Getting rid of the factory ammeter, and the iffy bulkhead connection of that circuit, should be top priority. There is a thread here somewhere. I think it's called something like the
Madd bypass
Madd bypass
that was excellent. Well written for anyone to follow. It also confirmed my albeit simplistic notion/approach that I do not want to generate with a high output alternator more amperage though the system (especially if not needed) than was provided by the original alternator. Besides just old wiring and iffy connections on a car this age, there are design flaws in the amp gauge arrangement/circuit that put the gauge and the circuit under a lot of ....'duress'. Anyway, thanks for pointing out that thread. At a bare minimum I'll know what and where to keep an eye on.
mopowers
Well-Known Member
How much of an improvement is the dual field alternator and VR? What is the improvement from?
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 25,642
- Reaction score
- 12,930
well, many people me included, have had the mechanical VRs stick on, and overcharge the battery, and start blowing light bulbs. But mostly the set points are too low. The headlamps end up being very dim, and the battery suffers from chronic undercharge.. They also seem to be temperature sensitive.
The electronic VRs solve all those issues. You can, or used to be able to, retrofit a VR designed for the old single fields. IDK if they are still available. You can retrofit an isolated field 70up alt into an older chassis by grounding the one extra brush terminal. But you,normally, would not try to fit an older alt into a 70up chassis.
The new VRs control the ground circuit to the field, varying the field strength to affect the charging. The older mechanicals varied the field strength on the power side. The alternator doesn't care which side is regulated, but the VRs sure do. The electronic VRs seem to last for decades. The alternators too, just requiring occasional bearings and brushes, all very cheap parts. The front bearing needs a special puller to replace, but the puller is cheaper than a rebuilt alternator! Go figure! The rest of the alternator parts are practically engineered to last ,oh let's see I think mine is a 70's model,actually,so 50 years on the same armature and field coil. OOps I think I replaced the field once,not sure exactly,lol, which car that was in. It mighta been in my 73 Swinger. Hyup, time marches on........Actually, this current alt may be the same one that was in my 73,heehee. In which case it has been in nearly continuous use since new. WOW!
The electronic VRs solve all those issues. You can, or used to be able to, retrofit a VR designed for the old single fields. IDK if they are still available. You can retrofit an isolated field 70up alt into an older chassis by grounding the one extra brush terminal. But you,normally, would not try to fit an older alt into a 70up chassis.
The new VRs control the ground circuit to the field, varying the field strength to affect the charging. The older mechanicals varied the field strength on the power side. The alternator doesn't care which side is regulated, but the VRs sure do. The electronic VRs seem to last for decades. The alternators too, just requiring occasional bearings and brushes, all very cheap parts. The front bearing needs a special puller to replace, but the puller is cheaper than a rebuilt alternator! Go figure! The rest of the alternator parts are practically engineered to last ,oh let's see I think mine is a 70's model,actually,so 50 years on the same armature and field coil. OOps I think I replaced the field once,not sure exactly,lol, which car that was in. It mighta been in my 73 Swinger. Hyup, time marches on........Actually, this current alt may be the same one that was in my 73,heehee. In which case it has been in nearly continuous use since new. WOW!
Last edited:
First your alternator output. As far as I know, no remafgr' has ever sorted through the different parts. So if you have a remfged alternator it can be any one of the 3 different output ratings ( 36 and 42 the most common ).
Now about wiring harness concerns... Resistance in circuitry causes heat. In many cases that's by design. Your thermal gauges are a good example. A mere 3 volts pulsing through this circuit generates heat in 3 resistor coils to move 3 gauge needles.
Same resistance happens at weak connections and in some cases the location of that is also by design.
To bypass the old weak connection at the fusible link and bulkhead connector outside in the engine bay will simply move that weak link to other locations inside the cabin.
Sure some amp gauges have failed but no more frequent than ignition switch connections, headlight switch connections, on and on. I do have issue with the amp gauge, how they are wired into a system. Its failure will shut down the whole car. So I wont argue with replace it with a volts gauge ( madelectrical pages wont help with that ).
Nobody will periodically service and maintain a wiring harness. Service and repair as required is the norm.
I just never will see the madelectrical method ( drill through and shove continuous wire though the bulkhead ) a proper service repair. New wire terminals are available. Previously unused ports in the bulkhead connectors are present. Thus a proper service repair is doable.
Now about wiring harness concerns... Resistance in circuitry causes heat. In many cases that's by design. Your thermal gauges are a good example. A mere 3 volts pulsing through this circuit generates heat in 3 resistor coils to move 3 gauge needles.
Same resistance happens at weak connections and in some cases the location of that is also by design.
To bypass the old weak connection at the fusible link and bulkhead connector outside in the engine bay will simply move that weak link to other locations inside the cabin.
Sure some amp gauges have failed but no more frequent than ignition switch connections, headlight switch connections, on and on. I do have issue with the amp gauge, how they are wired into a system. Its failure will shut down the whole car. So I wont argue with replace it with a volts gauge ( madelectrical pages wont help with that ).
Nobody will periodically service and maintain a wiring harness. Service and repair as required is the norm.
I just never will see the madelectrical method ( drill through and shove continuous wire though the bulkhead ) a proper service repair. New wire terminals are available. Previously unused ports in the bulkhead connectors are present. Thus a proper service repair is doable.
another article for reference - hits nail on the head for my '68 conv. . fwiw
Electronic-Voltage Regulator And Alternator - Mopar Muscle Magazine
Electronic-Voltage Regulator And Alternator - Mopar Muscle Magazine
It is a crap shoot whether a parts store alternator has the matching rotor and stator. Of if they even did anything more than clean the exterior and spray it with some paint. In some ways better off with a junk yard find and replace the bearings and brushes as needed. Or you can buy a real numbers matching restoration, but of course those carry a premium price.
To amplify on what was stated earlier in this thread, the test specs and the labeled (or claimed) amp rating never match because they are done at based on different points in the performance curves. Power out is controlled by the guts (rotor and stator), rpm and voltage to the field windings. Amperage output is based on demand. So to reiterate a point made earlier in this thread, a higher output alternator will not neccessarily place more load on connections. It could put more amps through a poor one in some circumstances.
1968 Plymouth Alternator specs from page 8-96 of the Service Manual.
Field Current draw at 12 V: 2.38 to 2.75 amps (max)
Current Output:
Standard w/ slant 6, 26 Amps
Standard all others, 34.5 Amps
Heavy Duty or with A/C, 44 Amps
Special Equipment, 51 Amps
All above are allowed plus minus 3 Amps for temperature variation.
Current Output above is measured at the alternator with the engine at 1250 RPM and 15 Volts. If current is measured at Battery, output is expected to be approximately 5 Amps less. Voltage is controlled by a variable load (carbon pile) across the battery.
The outputs are not the maximum current.
Change the rpm, or change the voltage to the field and the amps out can be changed.
The newer style alternators do in general seem to be slightly more efficient.
The 'square backs' are easier to service.
It is unclear why Chrysler chose to switch from regulating the hot side of the field windings to the ground side when they switched to an electronic voltage regulator in 1970. But that is the entire difference between the 'single field' and 'two field' systems. As far as performance goes, either approach works equally well and can be done electronically.
Fairly in-depth discussion at ST, including a link to 70s or 80s Dodge shop manual * which actually shows the factory test outputs by nominal amp rating (instead of the descriptions such as "Heavy Duty").
How Alternators are "Upgraded" • Speed Talk
At some point, Mopar Performance found their electronic regulators for the single field wire systems were not surviving. Their solution apparently was to say it was a race only item.
Nowadays many replacement regulars are electronic guts instead of points. The question then is of quality. For that reason, when my last p-part died I switched to a NAPA Echilen equivalent VR1001 (listed for Studabakers) and just picked up a Standard VR 128 as backup. Both made in the USA and have a good reputation.
One of the worst situation for an ammeter circuit like ours (shunt at the meter in the dash) is using the alternator to recharge a fully discharged battery while driving.
*Hotlink of shop manual image from photobucket. Original posted by KThaxton in the Ramcharger truck forums. http://i438.photobucket.com/albums/qq109/kthaxton_photo/scan-2.jpg
To amplify on what was stated earlier in this thread, the test specs and the labeled (or claimed) amp rating never match because they are done at based on different points in the performance curves. Power out is controlled by the guts (rotor and stator), rpm and voltage to the field windings. Amperage output is based on demand. So to reiterate a point made earlier in this thread, a higher output alternator will not neccessarily place more load on connections. It could put more amps through a poor one in some circumstances.
1968 Plymouth Alternator specs from page 8-96 of the Service Manual.
Field Current draw at 12 V: 2.38 to 2.75 amps (max)
Current Output:
Standard w/ slant 6, 26 Amps
Standard all others, 34.5 Amps
Heavy Duty or with A/C, 44 Amps
Special Equipment, 51 Amps
All above are allowed plus minus 3 Amps for temperature variation.
Current Output above is measured at the alternator with the engine at 1250 RPM and 15 Volts. If current is measured at Battery, output is expected to be approximately 5 Amps less. Voltage is controlled by a variable load (carbon pile) across the battery.
The outputs are not the maximum current.
Change the rpm, or change the voltage to the field and the amps out can be changed.
The newer style alternators do in general seem to be slightly more efficient.
The 'square backs' are easier to service.
It is unclear why Chrysler chose to switch from regulating the hot side of the field windings to the ground side when they switched to an electronic voltage regulator in 1970. But that is the entire difference between the 'single field' and 'two field' systems. As far as performance goes, either approach works equally well and can be done electronically.
Fairly in-depth discussion at ST, including a link to 70s or 80s Dodge shop manual * which actually shows the factory test outputs by nominal amp rating (instead of the descriptions such as "Heavy Duty").
How Alternators are "Upgraded" • Speed Talk
At some point, Mopar Performance found their electronic regulators for the single field wire systems were not surviving. Their solution apparently was to say it was a race only item.
Nowadays many replacement regulars are electronic guts instead of points. The question then is of quality. For that reason, when my last p-part died I switched to a NAPA Echilen equivalent VR1001 (listed for Studabakers) and just picked up a Standard VR 128 as backup. Both made in the USA and have a good reputation.
One of the worst situation for an ammeter circuit like ours (shunt at the meter in the dash) is using the alternator to recharge a fully discharged battery while driving.
*Hotlink of shop manual image from photobucket. Original posted by KThaxton in the Ramcharger truck forums. http://i438.photobucket.com/albums/qq109/kthaxton_photo/scan-2.jpg
Last edited:
I see recommended for this car per references I've used is a 60A rated one which will be close enough for my purposes -thanks for all input - good discussion. I happen to like the dash ammeter - reminds me of the one on headlamp of my '72 Triumph....yes, plenty of issues with that arrangement as well...sometimes the best solution is carrying a fire extinguisher.
-
