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Discussion Topic:
It was Smoking
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Dream38v8 |
08-25-2026 @ 1:11 PM
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Member
Posts: 240
Joined: May 2016
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I know I connected something incorrectly. My question is what did I do wrong?
I got the car running a few weeks ago. I noticed the gauges would work intermittently. On my last drive I noticed the amp gauge was not charging, but if I turned on the lights it would discharge. I ran a test. I disconnected the positive battery cable and the engine stopped. Hence a bad generator. I replaced the generator brushes and reconnected the cut-off and battery. As I was attempting to start the car the amp gauge was negatively pegged. I turned the car off and the gauge returned to 0. I tried to start the car again. This time smoke came from under the dash and hood. I tuned the car off and disconnected the battery. The cut-off was smoking and the plus the ignition wire to the solenoid. Smoke under the dash appeared to be coming from the back of the gauges. After the smoke cleared I crawled under the dash. The wire from the wiring harness to the amp gauge was disconnected. I looked as if the connector had burned or melted off. Also the yellow plastic wire covering was melting through the wiring harness. I know the car will require a new cutoff, solenoid and under dash wiring harness. What else? As I stated earlier what did I do incorrectly? The first pic is from under the dash and the second is at the solenoid,
Ray
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Dream38v8 |
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08-26-2026 @ 12:28 PM
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Member
Posts: 240
Joined: May 2016
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Today I had time to do a little investigating. I took the generator apart and it looks fine. No loose wires and none touching the outside case. The one new think I found was the cutout connection. It looked as if it was extremely hot. The outside are around the connection has smoke damage.
Any ideas.
Ray
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flatfoot |
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08-27-2026 @ 9:37 AM
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Member
Posts: 304
Joined: Mar 2011
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What year is the car you are working on?
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Dream38v8 |
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08-27-2026 @ 10:12 AM
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Member
Posts: 240
Joined: May 2016
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Flatfoot, my car is a 1938 Fordor Deluxe.
Ray
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Dream38v8 |
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09-07-2026 @ 1:50 PM
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Member
Posts: 240
Joined: May 2016
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I'm thinking the issue was caused by the cut-off shorting out. Therefore I am considering replacing the generator and associated electrical gear with a 6 volt alternator and electric fan. I am seriously considering making this switch since '38 is not a show car. Any comments on what else to consider regarding my proposed switch.
Thank you,
Ray
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carcrazy |
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09-07-2026 @ 4:56 PM
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Senior
Posts: 2152
Joined: Oct 2009
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You might want to consider going with a 12V negative ground electrical system using an alternator.
The disadvantages associated with going to 12V are you will have to change some of the 6V items in the car like the battery, starter motor, coil, all light bulbs and any blower motors or overdrive solenoids.
The advantages of going to 12V are you can use a common alternator from a GM car as either a new or rebuilt unit that will have 63 amp current output. The alternator you want to use is most likely the GM Model 10 SI which has a built in voltage regulator. This was standard on all GM cars and trucks built from 1973 through 1985. You will want to use a DA Plug (it is a Diode) which prevents the alternator current from flowing backward through the ignition circuit after you shut the engine off. If you buy a rebuilt alternator from one of the auto parts stores like AutoZone, you will have to pay an additional core charge of $10 to $15 because you won't have a core to trade in. Once you have the car converted to 12V, you will be able to use modern 12V accessories to make the car a reliable everyday driver. These accessories include radios, cruise control and if you want it, air conditioning.
Many more items need to be addressed when doing a 6V to 12V conversion. A good source of information about this swap is "The Official 12-Volt Conversion Guide" by Randy Rundle of Fifth Avenue Antique Auto Parts.
This message was edited by carcrazy on 9-7-26 @ 5:07 PM
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Dream38v8 |
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09-08-2026 @ 5:31 AM
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Member
Posts: 240
Joined: May 2016
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Thanks Carcrazy for the info regarding switching to a 12V negative ground system. I plan to stay with the 6V positive ground system. The next owner may want to keep the car original. Currently the only non stock items are the Fender headers and fog lights. Hence the car is very original. What I am looking for is info needed to accomplish the change to an alternator. . What else is required besides the fan and alternator? What vendor has the best equipment and support?
Ray
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51504bat |
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09-08-2026 @ 6:18 AM
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Member
Posts: 395
Joined: Apr 2020
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First off, I'm a 12 volt guy but understand if you want to remain true with 6 volt positive ground. I've used these guys for 3 alternators, 2 for flatheads and one for the 302 in my '54 Ranch Wagon. Worth checking them out. IMO
https://www.qualitypowerauto.com/item_24/6-Volt-Alternators-Positive-Ground.htm
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Kens 36 |
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09-08-2026 @ 7:39 AM
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Member
Posts: 431
Joined: Oct 2009
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Are there issues to consider with the fan mounting on the alternator?
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carcrazy |
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09-08-2026 @ 4:41 PM
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Senior
Posts: 2152
Joined: Oct 2009
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You can buy a 6V alternator from Fifth Avenue. It will be a 6V negative ground unit but that shouldn't present any problems unless you have a modern electronic vibrator in you radio. The original mechanical radio vibrators will work fine with either positive or negative ground.
Fifth Avenue also offers a 6V electrical cooling fan with metal mounting straps to allow you to mount the fan motor to the sh*ll of the radiator rather than to the radiator core. They also offer everything else you need to install an alternator on your engine. Other vendors also offer the pulley and mounting bracket for the alternator. Some of the other vendors may have less expensive parts.
https://fifthaveinternetgarage.com/index.php
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