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Dim headlights on a 1947 Lincoln


djwlz
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I have a 1947 Lincoln Continental, and it has always had dim headlights.  It was rewired many years ago, with period correct type of wiring.  One mechanical minded person suggested I change out the headlight switch, which is not easy on these cars; in fact it appears the radio has to come out to do this.  Does anyone have experience with the electrical system on these cars?

Thank you for reading this.

Don 

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I am sure there will be more educated advice given that can help. I can only offer a simple approach to the problem.

First, make sure all your grounds are tight and clean/metal-to-metal. Even check inside the bulb sockets to see if there is any oxidation and clean up the contacts.

Also, is the generator working? Is it charging the battery? 

Normally with a generator if you rev the engine the lights will get brighter. Is that happening?

 

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  Ya'll would not care for what I would do. So a compromise.  For a check.  Locate the closest junction/connection to the headlight. Run a jumper from the hot post on the battery.  Jumper wire to be at least a 12 gauge. Brighter?   Yep, too much resistance in the system. Now you know. At this point, I would install relays, triggered by the original circuit.

 

  Ben

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You can use a volt-ohm meter: Attach one lead to a good ground and then with the lights on use the other lead follow the wiring from the battery to the lights and see where the voltage drops are. Those are the spots with high resistance that need to be dealt with.

 

Or, if that is too difficult and you don't mind inauthentic wiring install new heavy gauge wiring from the generator or battery with relays to control it all.

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Dim headlights are most often a sign of a bad ground. Use a power probe from your local mechanic to supply power to the back of the headlight while it is off. If the light is brighter with the jump from the power probe you have a power supply / resistance issue on the feed side. If the light remains dim, its a ground issue or bulb problem(unlikely). Also just jump a power and ground to the light to check brightness incase there is a bulb issue. Should be simple to figure out.

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16 hours ago, Buffalowed Bill said:

If your car has old sealed beams exchange them for new ones. I don't know why, but sealed beams do loose their illumination capability over time.

Nor do sealed beams even begin to match the brightness of automobile lighting available today. 

 

I guess what I am saying is that what seems dim today may have been standard and acceptable back in 1947.

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With the lights on put your hands on the plug socket at the seal beam. If it feels warm it is an indication of poor ground. I do not know the colour of the wires at that particular spot but most likely the ground wire is black and the end is usually grounded on the body (fender) If so remove and clesn the ground . All 12 volts suffer from poor grounds. Needs frequent service, especially battery cables.

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16 hours ago, trini said:

With the lights on put your hands on the plug socket at the seal beam. If it feels warm it is an indication of poor ground. I do not know the colour of the wires at that particular spot but most likely the ground wire is black and the end is usually grounded on the body (fender) If so remove and clesn the ground . All 12 volts suffer from poor grounds. Needs frequent service, especially battery cables.

 

Trouble is the fender may not make for a good ground either.

Do your testing with a substantial clip lead and start at the battery ground side.

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My go-to tool for 6V wiring issues is a 10-foot length of 10-gauge wire with alligator clips on the ends, used to temporarily supply a better ground--among other things.  Even before the VOM.  If the lights brighten, figure out what to clean or how to add a permanent supplemental ground.  Sometimes it's necessary to try different areas for the ground, such as frame.

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