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'41 Special Charging Troubles


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The generator in my 41 mod 47 has made squeaking noise since I got it a little over a year ago. I bought a replacement generator last year but inertia set in and I didn't get to it till this year. The old one was making so much noise I had a hard time tuning and balancing the new carb setup. I had to swap out the pulley and I put the new generator in the car. No charge. I polarized the generator, no change. I put the old one back in. No charge. Polarized that one, no difference. I took both up to the generator shop and they checked them out. Both are good. I bought a NOS Delco-Remy regulator. Put that in and it made no difference. I didn't think it would but I thought I had to try.

About the Amp meter: When I start the car the amp meter used to show a charge and gradually drop to zero. Now it shows a very slight negative charge with the engine running and does not move as rpms are increased. If the headlights are on it shows discharge. Increasing the rpms makes no difference.

Battery: Voltage at the battery is 6.25. Voltage is 6.25 at the regulator Batt terminal engine off. Engine on, 6.15 V.

Gen shows 0.00V across the Arm terminal to ground. Gen to block no resistance i.e. ground is good.

The wiring harness is a little crispy-crunchy so I ran a pair of new wires from the generator to the voltage regulator. No difference. I double checked that the it was hooked up correctly. It's all good.

 

I am stumped. What do you guys think?

 

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There are two methods for polarization.   One for internally grounded generator field coils and one for externally grounded  generator

field coils.     Your unit  has externally grounded field coils.

 

So......which polarization method did you use ??

 

Jack Worstell

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Jack, I was told it was internally grounded and so I used that method. I hope I didn't fry anything. I am a little concerned because output at the generator is 0.00 volts right now. That is measured from the armature terminal to ground.

 

Don, I checked the ground on the regulator and it is good.

 

 2carb, Jumper wire? from where to where? I did use a jumper wire from the field wire but at the regulator end. I jumped it to the batt terminal on the regulator. Got a healthy spark too. I've been keeping the battery well charged.

 

 

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Posted (edited)

Jack,

 

I called the generator repair shop and shop manager agrees with you, the generator is externally grounded. I polarized the generator by momentarily jumping the Gen to Batt terminals on the regulator. Still no charge. I checked the voltage output at the regulator and at the generator both 0.00 volts. Got the generator blues. If the governor doesn't shut everything down I'm going to take it into the shop.

 

Dave

Edited by Dave_B
added content (see edit history)
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Dave....I have heard that you can take the field wire off of the regulator and

( with the motor doing about 1000RPM)   touch the end of this field wire

briefly to ground.

If then the ammeter shows charge....then the trouble

is in the regulator.  And if no charge...

then the trouble is in   the generator

 

 

 

This doesn't fix the problem but it does narrow the search

 

I have never done this test  myself...but I'm fairly sure

it should work

 

Jack Worstell

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Sounds to me like it's time to get into the regulator, even if you've replaced it with a new or rebuilt one. If the gen shop tested both generators and they were both putting out the correct volts and amps and were reinstalled correctly then the culprit is either the regulator or the wiring.  Is the regulator new ,rebuilt or the same one that is on the car? Just my 2cvents worth.

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Posted (edited)

Jack, Bloo and company,

I drove it up to Baltimore this morning on the battery to the shop that checked out the generators. The I95 traffic was light, thankfully. I got there and they were able to take me right away. The tech (old guy with slightly more hair than me) came out with a helper and his multi meter and got right to work. We all kept our distance like we're supposed to. He checked a few things out and in about 15 minutes he had sussed out. Now here is the embarrassing part of the story...... The wires at the generator were reversed. Damn I'm sure I checked that out but I still I had it backwards. Mark you were right, it was the wiring. That was what I was thinking too but I forgot Occam's Razor, the simplest answer is most likely the right answer.

 

Sorry to get everyone excited for nothing. Anyway, Here's the good news, it was a 75 mile round trip, 95% of which was interstate at 60-65 mph, I used 4.48 gallons of gas. Do the math, 16.74 mpg. Something must be wrong here that can't be and yet there it is. I'll keep an eye on it and see if I can repeat those results.

 

Thank you, all. You guys are the best.

Dave

Edited by Dave_B
math correction (see edit history)
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Dave glad you got it figured out and fixed. The guy who taught me my mechanics early on stressed the phrase "START WITH THE SIMPLE AND WORK TO THE COMPLEX" !!! Don't ask me how many times over the years that I've forgotten that. We are all guilty on that account.......LOL!!! Laughing with you not at you !!! 

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On 3/24/2020 at 12:13 PM, Dave_B said:

Jack, Bloo and company,

I drove it up to Baltimore this morning on the battery to the shop that checked out the generators. The I95 traffic was light, thankfully. I got there and they were able to take me right away. The tech (old guy with slightly more hair than me) came out with a helper and his multi meter and got right to work. We all kept our distance like we're supposed to. He checked a few things out and in about 15 minutes he had sussed out. Now here is the embarrassing part of the story...... The wires at the generator were reversed. Damn I'm sure I checked that out but I still I had it backwards. Mark you were right, it was the wiring. That was what I was thinking too but I forgot Occam's Razor, the simplest answer is most likely the right answer.

 

Sorry to get everyone excited for nothing. Anyway, Here's the good news, it was a 75 mile round trip, 95% of which was interstate at 60-65 mph, I used 4.48 gallons of gas. Do the math, 16.74 mpg. Something must be wrong here that can't be and yet there it is. I'll keep an eye on it and see if I can repeat those results.

 

Thank you, all. You guys are the best.

Dave

 

Dave -- Congrats on your impressive gas mileage in your '41!  Reminds me of the time an old Nash owned by a friend of mine pulled some astonishing mileage on a trip, having traveled many miles on the first leg of the trip while needing very little gas to refill the tank.  Too good to be true, of course.  Turned out a little later that a plugged tank vent (combined, presumably, with a very healthy fuel pump) had caused atmospheric pressure to partially crush the tank!!! 

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