The Ford Barn

Cartravel · 05-07-2015, 03:22 PM

I am having trouble with the generator/regulator on my Allard. It is a 12v Lucas generator and a CAV (similar to Lucas) voltage regulator or control box. These units have only a cutout and voltage regulator (no current regulator), otherwise it should be similar to a Ford regulator. I have tried several tests – some from the Lucas manual, some from the Ford “Generator and Starting System Manual, 1933-47” and some others I’ve found on the net.

First, I measured the resistance of the armature at 0.7 ohm and the field at 7.6 ohm. I don’t know what the specs should be.

Test 1: (from Lucas manual) to test armature – disconnect leads at generator and measure voltage from armature to ground. Since the fields have only residual magnetism, I should get only 2-3 volts, I get 2.4, so it passes that test.

Test 2: (from Lucas manual) to test fields – leave voltmeter in place from previous test and connect armature to field measuring current between them. I should be able to speed the engine up to get 12v on the voltmeter with less than 2 amps flowing to the field. I can get no more than 2.5v when I speed it up and amperage is negligible. So, it fails that test. Test shows open in field coil, but I measured 7.6 ohms.

Test 3: (from the net) – Leave voltmeter as above (between armature and ground). Connect lead from field to ground. I get about 15v at idle and >35 if I rev it. This says the generator is good.

Test 4: If I run it as a motor with 12v to the armature and the field grounded. It runs fine and consumes 4.3 amps.

Test 5: From Ford manual – Connect ammeter between armature and terminal on regulator and connect armature to field. I get nothing.

I ran most of these tests before taking the regulator and generator to the only shop in town that deals with this old stuff. They went through it, not sure what they replaced and pronounced both the generator and regulator good. I took the generator back a second time. They put it on some sort of machine and said this means it is good. I think the machine may have been like my motoring test. So, I guess I’m on my own to figure this out. I think there is a problem with the fields, but don’t know how I can get it fixed. Any thoughts?
Thanks,
Larry Young

Lawrie · 05-07-2015, 03:51 PM

If you have access to the ford service bulletins,they list the info on the resistance on the field coils and armature,for 6v,I just did some work on my spare 33 6v generators and the field resistance was only 1.2 ohms by the book,so yours seems a lot higher,I don't know if 12v would be that different,the service bulitin says if the resistance is high look for a bad connection on the wires in the field coils.
one thing I found if the wires to the brushes were not routed nicely one would hold off the output brush from the armature.
also make sure the regulator/cutout is earthed well and maybe run a wire from the generator case to the regulator cutout earth.
lawrie

Kurt in NJ · 05-07-2015, 08:56 PM

What trouble are you having?/
With Lucas gen and lucas regulator that I have worked on to "full field" the generator to make max output power is put to the field wire ----but perhaps your gen has been modified??

there are baisically 2 different types of systems, one the field wire is grounded to make full output --with this type the internal end of the field wire is connected to the non grounded brush (armature terminal)---the other the field is grounded inside the generator

What Lucas generator is the car using?

Cartravel · 05-07-2015, 10:37 PM

The problem is that it shows no charge at the ammeter. I will check the model in the morning. Should be same as Ford Pilot and probably others. Yes, of the two types this should produce full power when the the field and armature are connected. But mine seems to work the other way (power with field grounded). The generator has not been modified, but I did change to negative ground. Should this require modification of the wiring? I think it did charge after that change, but stopped working later on. TIA

Cartravel · 05-07-2015, 10:46 PM

The Ford manual only has a few 12 v generators. They have higher resistance (5-6 ohm field) than the 6v generators. I have not been able to find the specs for this one, but they don't seem to be too far out of whack.

GB SISSON · 05-07-2015, 11:20 PM

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Us British motorcycle owners know why the Brits drink warm beer. It's because they have Lucas refrigeration....

koates · 05-08-2015, 02:32 AM

Cartravel, You are probably being over technical by doing all those resistance and other tests. All you need to do to test a lucas generator is the following. On the car, disconnect all wires off the generator terminals. Using a small jumper wire connect the generator field terminal to the gen armature terminal. The poms call the armature terminal the dynamo terminal. Connect your analogue voltmeter (works better than a digital meter) negative to ground as you said that's how the battery was connected. Connect positive voltmeter lead to gen armature terminal. Start engine and rev to say 2000 RPM and voltage should go quickly up to 30 to 50 volts. If it does not produce this voltage then the generator is faulty. If the field coils inside the generator have been modified then connect the field terminal to ground and repeat the test. I don't know why that modification would be done because the generator would not work with the lucas or CAV voltage regulator which requires a field to armature circuit not a field to ground circuit. What is the history of this Allard car ? Is the generator original to the car ? Did it ever work during your ownership. Allards were originally Positive to ground battery. Let me know the results of this test and then we can proceed further. Regards, Kevin.

old Tom · 05-08-2015, 08:24 AM

I do not think the field is making magnetism. Full fielding it is simple. With it running at 1/2 throttle, and the wire connected to the armature, jump battery voltage to the F terminal. The output should be above battery voltage. Do this for a minute or so only if it is charging. If no change, the field is open. (usually the field has 4 ohms or so of resistance. Jim

Tests 2 and 5 sound like something applicable to a "B" circuit charging system. Test 3 applies to an "A" circuit system. The reported results seem to indicate it is an "A" circuit generator that is working properly. Ford used a lot of "B" circuit systems. Do you by chance have an "A" generator mated with a "B" regulator? That won't work. Check what you actually have and make sure you aren't doing mix-n-match with the wrong parts. Unless you get more specific with "having trouble" help will be limited.

Cartravel · 05-08-2015, 08:55 AM

This car was restored about 20 years ago. I bought it a few years later. The charging system did work. I have converted it to negative ground. I have already done the tests suggested and agree it acts like a type A when it should be a type B. Don't know how that could happen unless the generator shop rewired it wrong. I'll check the wiring.

Bruce Lancaster · 05-08-2015, 09:41 AM

A and B refer to USA Ford and delco types...this may or may not be either. USA Ford info does NOT connect here at all, this thing is Lucas and not used on any USA or Canada Ford, not covered in our literature! Posts 7 and 8 seem useful, forget USA Bulletins and the A-B thing.
If you can't sort it I think it may be covered in the postwar Ford England shop manual covering Pilot and big trucks...PM me and I'll see if I can dig it up. Ford England had, I think, stopped using Ford Canada/USA type electrics by the period after WWII and I think was mostly or all Lucas on theri flathead V8's they made up to about '55.

Cartravel · 05-08-2015, 11:15 PM

Ok, thanks for the suggestions. I took the back off and sure enough the generator was wired wrong. Since it did work in the past and no one but the local shop has touched it. I've concluded they wired it up wrong, despite their claims to the contrary. I was led astray by doing tests for a type B, when it was wired as a type A. I knew which type I was supposed to have. When the full field test didn't work the first time I took it in for repair. Whew, they sure cost me a lot of time, but I did learn something.

05-07-2015, 03:22 PM	#1
Cartravel Senior Member Join Date: May 2010 Location: Larry Young, Tulsa, OK Posts: 202	Generator/regulator on British flathead I am having trouble with the generator/regulator on my Allard. It is a 12v Lucas generator and a CAV (similar to Lucas) voltage regulator or control box. These units have only a cutout and voltage regulator (no current regulator), otherwise it should be similar to a Ford regulator. I have tried several tests – some from the Lucas manual, some from the Ford “Generator and Starting System Manual, 1933-47” and some others I’ve found on the net. First, I measured the resistance of the armature at 0.7 ohm and the field at 7.6 ohm. I don’t know what the specs should be. Test 1: (from Lucas manual) to test armature – disconnect leads at generator and measure voltage from armature to ground. Since the fields have only residual magnetism, I should get only 2-3 volts, I get 2.4, so it passes that test. Test 2: (from Lucas manual) to test fields – leave voltmeter in place from previous test and connect armature to field measuring current between them. I should be able to speed the engine up to get 12v on the voltmeter with less than 2 amps flowing to the field. I can get no more than 2.5v when I speed it up and amperage is negligible. So, it fails that test. Test shows open in field coil, but I measured 7.6 ohms. Test 3: (from the net) – Leave voltmeter as above (between armature and ground). Connect lead from field to ground. I get about 15v at idle and >35 if I rev it. This says the generator is good. Test 4: If I run it as a motor with 12v to the armature and the field grounded. It runs fine and consumes 4.3 amps. Test 5: From Ford manual – Connect ammeter between armature and terminal on regulator and connect armature to field. I get nothing. I ran most of these tests before taking the regulator and generator to the only shop in town that deals with this old stuff. They went through it, not sure what they replaced and pronounced both the generator and regulator good. I took the generator back a second time. They put it on some sort of machine and said this means it is good. I think the machine may have been like my motoring test. So, I guess I’m on my own to figure this out. I think there is a problem with the fields, but don’t know how I can get it fixed. Any thoughts? Thanks, Larry Young

05-07-2015, 03:51 PM	#2
Lawrie Senior Member Join Date: May 2010 Location: Qld, Australia Posts: 4,212	Re: Generator/regulator on British flathead If you have access to the ford service bulletins,they list the info on the resistance on the field coils and armature,for 6v,I just did some work on my spare 33 6v generators and the field resistance was only 1.2 ohms by the book,so yours seems a lot higher,I don't know if 12v would be that different,the service bulitin says if the resistance is high look for a bad connection on the wires in the field coils. one thing I found if the wires to the brushes were not routed nicely one would hold off the output brush from the armature. also make sure the regulator/cutout is earthed well and maybe run a wire from the generator case to the regulator cutout earth. lawrie

05-07-2015, 08:56 PM	#3
Kurt in NJ Senior Member Join Date: May 2010 Location: on the Littlefield Posts: 6,156	Re: Generator/regulator on British flathead What trouble are you having?/ With Lucas gen and lucas regulator that I have worked on to "full field" the generator to make max output power is put to the field wire ----but perhaps your gen has been modified?? there are baisically 2 different types of systems, one the field wire is grounded to make full output --with this type the internal end of the field wire is connected to the non grounded brush (armature terminal)---the other the field is grounded inside the generator What Lucas generator is the car using?

05-07-2015, 10:37 PM	#4
Cartravel Senior Member Join Date: May 2010 Location: Larry Young, Tulsa, OK Posts: 202	Re: Generator/regulator on British flathead The problem is that it shows no charge at the ammeter. I will check the model in the morning. Should be same as Ford Pilot and probably others. Yes, of the two types this should produce full power when the the field and armature are connected. But mine seems to work the other way (power with field grounded). The generator has not been modified, but I did change to negative ground. Should this require modification of the wiring? I think it did charge after that change, but stopped working later on. TIA

05-07-2015, 10:46 PM	#5
Cartravel Senior Member Join Date: May 2010 Location: Larry Young, Tulsa, OK Posts: 202	Re: Generator/regulator on British flathead The Ford manual only has a few 12 v generators. They have higher resistance (5-6 ohm field) than the 6v generators. I have not been able to find the specs for this one, but they don't seem to be too far out of whack.

05-07-2015, 11:20 PM	#6
GB SISSON Senior Member Join Date: Jan 2014 Location: Orcas Island Washington Posts: 4,916	Re: Generator/regulator on British flathead Sponsored Links (Register now to hide all advertisements) Us British motorcycle owners know why the Brits drink warm beer. It's because they have Lucas refrigeration.... __________________ Owner/Operator of 'Jailbar Ranch' on the side of Mt. Pickett. Current stable consists of 1946 1/2 ton pickup turned woodie wagon with FH V8, 1947 Tonner Pickup (red) mostly stock with exception of a cummins 6at turbo diesel, 1946 Tonner Pickup (green) with 226 cu in 6 cyl flathead, 1979 Toyota landcruiser wagon, completely encased in 1947 Ford Jailbar sheet metal. Ok, cornbinder rear fenders..... 'Rusty ol' floorboards, hot on their feet' (Alan Jackson)

05-08-2015, 02:32 AM	#7
koates Senior Member Join Date: May 2010 Location: Melbourne Australia. Posts: 2,078	Re: Generator/regulator on British flathead Cartravel, You are probably being over technical by doing all those resistance and other tests. All you need to do to test a lucas generator is the following. On the car, disconnect all wires off the generator terminals. Using a small jumper wire connect the generator field terminal to the gen armature terminal. The poms call the armature terminal the dynamo terminal. Connect your analogue voltmeter (works better than a digital meter) negative to ground as you said that's how the battery was connected. Connect positive voltmeter lead to gen armature terminal. Start engine and rev to say 2000 RPM and voltage should go quickly up to 30 to 50 volts. If it does not produce this voltage then the generator is faulty. If the field coils inside the generator have been modified then connect the field terminal to ground and repeat the test. I don't know why that modification would be done because the generator would not work with the lucas or CAV voltage regulator which requires a field to armature circuit not a field to ground circuit. What is the history of this Allard car ? Is the generator original to the car ? Did it ever work during your ownership. Allards were originally Positive to ground battery. Let me know the results of this test and then we can proceed further. Regards, Kevin.

05-08-2015, 08:24 AM	#8
old Tom Senior Member Join Date: May 2010 Posts: 195	Re: Generator/regulator on British flathead I do not think the field is making magnetism. Full fielding it is simple. With it running at 1/2 throttle, and the wire connected to the armature, jump battery voltage to the F terminal. The output should be above battery voltage. Do this for a minute or so only if it is charging. If no change, the field is open. (usually the field has 4 ohms or so of resistance. Jim Tests 2 and 5 sound like something applicable to a "B" circuit charging system. Test 3 applies to an "A" circuit system. The reported results seem to indicate it is an "A" circuit generator that is working properly. Ford used a lot of "B" circuit systems. Do you by chance have an "A" generator mated with a "B" regulator? That won't work. Check what you actually have and make sure you aren't doing mix-n-match with the wrong parts. Unless you get more specific with "having trouble" help will be limited.

05-08-2015, 08:55 AM	#9
Cartravel Senior Member Join Date: May 2010 Location: Larry Young, Tulsa, OK Posts: 202	Re: Generator/regulator on British flathead This car was restored about 20 years ago. I bought it a few years later. The charging system did work. I have converted it to negative ground. I have already done the tests suggested and agree it acts like a type A when it should be a type B. Don't know how that could happen unless the generator shop rewired it wrong. I'll check the wiring.

05-08-2015, 09:41 AM	#10
Bruce Lancaster Member Emeritus Join Date: May 2010 Location: Madison, NJ Posts: 5,230	Re: Generator/regulator on British flathead A and B refer to USA Ford and delco types...this may or may not be either. USA Ford info does NOT connect here at all, this thing is Lucas and not used on any USA or Canada Ford, not covered in our literature! Posts 7 and 8 seem useful, forget USA Bulletins and the A-B thing. If you can't sort it I think it may be covered in the postwar Ford England shop manual covering Pilot and big trucks...PM me and I'll see if I can dig it up. Ford England had, I think, stopped using Ford Canada/USA type electrics by the period after WWII and I think was mostly or all Lucas on theri flathead V8's they made up to about '55.

05-08-2015, 11:15 PM	#11
Cartravel Senior Member Join Date: May 2010 Location: Larry Young, Tulsa, OK Posts: 202	Re: Generator/regulator on British flathead Ok, thanks for the suggestions. I took the back off and sure enough the generator was wired wrong. Since it did work in the past and no one but the local shop has touched it. I've concluded they wired it up wrong, despite their claims to the contrary. I was led astray by doing tests for a type B, when it was wired as a type A. I knew which type I was supposed to have. When the full field test didn't work the first time I took it in for repair. Whew, they sure cost me a lot of time, but I did learn something.