I've been toying around with swapping over to 12v on my 41 truck. I have a 12v generator and coil from a 54 truck that tests good. Instead of going through the expense or hastle of fabbing an alternator bracket and using an alternator that doesn't look factory I thought it might be a good idea to use the 12v generator. I have 12v regulators laying around so that shouldn't be an issue. I could probably just swap the regulator and leave the 6v generator. It would work. I have the good 12v though so... I know I'll need new bulbs and a voltage reducer for my cab fans. Any reason I wouldn't want to do this? I like the idea of the motor spinning over faster and other benefits of the 12v system.
A 6V generator won't last long (if at all) trying to make 12 volts. 12V Delco-Remy generators have red painted ID tags- - - -6V units have black ones. The internal wiring of both armatures and field coils is different. There are also different amperage ratings for generators- - - -and the regulators might have to be adjusted to match up with the generator capacity. Don't "assume" you can just bolt up mismatched parts and expect them to play well together. Drop me a PM and I'll be glad to help you with the conversion- - - -I've been working with generator/regulator systems since the early1960s, as well as spending 30+ years teaching automotive electricity. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
A 6V generator won't last long (if at all) trying to make 12 volts. 12V Delco-Remy generators have red painted ID tags- - - -6V units have black ones. The internal wiring of both armatures and field coils is different. There are also different amperage ratings for generators- - - -and the regulators might have to be adjusted to match up with the generator capacity. Don't "assume" you can just bolt up mismatched parts and expect them to play well together. Drop me a PM and I'll be glad to help you with the conversion- - - -I've been working with generator/regulator systems since the early1960s, as well as spending 30+ years teaching automotive electricity. Jerry
Thanks Jerry. No assumptions being made. I went to school for electronics eons ago so I'm pretty comfortable with these things. I'm mainly posting because I know there are nuances with some of the old systems. Right now I have a 6v system that doesn't seem to be charging. I pulled the regulator and went through it already. Filed the points etc. It was very clean inside otherwise. I tested the 12v gens that I have in the garage, but I haven't tried putting power to the one in the truck to see if it'll spin. I measured voltage at the reg, but only got battery voltage (6.24v) on the batt and gen/arm connections. It was ~5v at the field. This was after revving it a little and also polarizing. I'm thinking the gen might need some attention at this point. I'll pull it to test and maybe put some brushes in, but this is where I'm wondering if I should just throw a 12v gen and reg at it.
"Clean"????? All that crud on the base looks like at least one of the coils has melted down. Have you checked the coils for continuity? Connect an ohmmeter between the Field terminal and the base of the regulator- - - -you should get close to zero resistance. Opening either of the spring-closed points will jump the resistance up to at least 2-3 ohms- - - - -they're wired in series. The coil behind the ARM terminal controls maximum amperage- - - -25-30 amps on most 6V systems. The one behind the FLD terminal controls max voltage against a fully charged battery- - - - -usually about 7.5 V. If the generator is OK, removing the wire at the FLD terminal and grounding it should make the voltage at the ARM terminal increase with engine RPM. Filing regulator points is a VERY bad mistake. It will make them stick. I use a strip cut from an index card or something similar to burnish regulator points, or if the points can be disassembled, clean them with a pencil eraser. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Not sure about the crud you're seeing. It looks pretty clean in person considering the age. Do you still see the crud in this pic? That's when I first opened the lid and seems to have better lighting.
I see a lot of residue where the coil assemblies are riveted to the base, like melted insulation from at least one of the coils. Those point assemblies look like they're permanently attached- - - -no way to remove the movable contacts for cleaning. Earlier versions were assembled with screws, not rivets. Regulator points are silver, not tungsten like ignition points, and they operate with a slight wiping action so they self-clean. Filing them creates scratches that cause them to stick instead of wipe. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
I see a lot of residue where the coil assemblies are riveted to the base, like melted insulation from at least one of the coils. Those point assemblies look like they're permanently attached- - - -no way to remove the movable contacts for cleaning. Earlier versions were assembled with screws, not rivets. Regulator points are silver, not tungsten like ignition points, and they operate with a slight wiping action so they self-clean. Filing them creates scratches that cause them to stick instead of wipe. Jerry
Understood. You might be seeing residue from me spraying contact cleaner that hadn't dried yet. Thanks for the info.
1. Connect an ohmmeter between the Field terminal and the base of the regulator- - - -you should get close to zero resistance. Opening either of the spring-closed points will jump the resistance up to at least 2-3 ohms- - - - -they're wired in series. Field to ground: 14 ohms closed. 32.6 ohms open. No change to field ohms test.When Gen/Arm points are pressed. GEN/Arm to gnd : Short to ground when closed. Bad point connection. Inconsistent measurements. Generator itself is cooked too. .4 vdc from gen/arm. 1mv when field is grounded.
2. The coil behind the ARM terminal controls maximum amperage- - - -25-30 amps on most 6V systems. The one behind the FLD terminal controls max voltage against a fully charged battery- - - - -usually about 7.5 V. If the generator is OK, removing the wire at the FLD terminal and grounding it should make the voltage at the ARM terminal increase with engine RPM. I'll give it a try when I reinstall it, but I think the regulator has a lot going on. I might just replace it.[u][/u]
That'll do it every time... At least one of the brushes wasn't even touching the commutator. It looks like a few mud wasps got pretty cozy in there. Everything tested well and should clean up nicely. I ordered some new brushes. Bushings and bearing are good. I'll pull, degrease and relube them. A coat of paint and it'll be good to go for another 100k miles...
Pretty crusty. Did you check the armature for proper magnetic induction with a growler? That's an essential test that all rebuilding shops do. Just using an ohmmeter isn't sufficient.
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Pretty crusty. Did you check the armature for proper magnetic induction with a growler? That's an essential test that all rebuilding shops do. Just using an ohmmeter isn't sufficient.
If a generator will "motor" it will also charge. Jerry
Last edited by klhansen; 03/27/20257:32 PM. Reason: fixed link
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Good resource, Jerry. I edited your post to include a direct link.
Mr. Rogers does a pretty good explanation.
I see there's also a link on that page for testing voltage regulators. Might come in handy for someone as well.
The same motoring test for generators is in the 47-51 Truck Service manual also. I did that when I rebuilt my generator with new brushes and bearings.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Back in the dark ages when I learned my trade at my father's shop, most starters and generators were rebuilt "in-house"- - - -right down to changing bushings, field coils, etc. Armatures got growler tested, commutators lathe turned, and checked for shorts, grounds, etc. We also did a limited amount of regulator repair, particularly on the 6-coil heavy duty Delco-Remy units a trucking company sent us for rebuilding and recalibration on a 6 month cycle. The generator and regulator combo was assigned a unique ID number, and they were swapped out on a time or mileage basis, depending on the kind of service the truck was used for, long haul or local. The company claimed its "on road" charging system failures dropped by over 90% after going to that maintenance routine. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
I just gave away a 6v and a 12v generator - I converted to a 12v alternator.
~ Rick
1947.1 GMC EC152 [228ci + 4spd] "Love at Last" Follow in the DITY 1968 Firebird [350-4 + th400] 2022 Tacoma I've been more of a car guy - but always wanted to get an old pickup
