The Ford Barn

joedaless · 05-18-2015, 05:52 PM

Hi All,
I recently changed to 12 volt on my 41 Ford Coupe. I now have a non working sending unit. My heat and cold gauge now when I shut the car off goes all the way to H when it is off. The charging gauge stays right in the middle when running . When I put the lights on it is discharging a little bit. Can anyone tell me what I did wrong. Me and the electrical parts on my antique cars never got along. Any and all help will be very much appreciated.
Thanks ,
Joe D

51 MERC-CT · 05-18-2015, 06:02 PM

Quote:

Originally Posted by joedaless

Hi All,
I recently changed to 12 volt on my 41 Ford Coupe. I now have a non working sending unit. My heat and cold gauge now when I shut the car off goes all the way to H when it is off. The charging gauge stays right in the middle when running . When I put the lights on it is discharging a little bit. Can anyone tell me what I did wrong. Me and the electrical parts on my antique cars never got along. Any and all help will be very much appreciated.
Thanks ,
Joe D

To start with do you have a voltage reducer or reducers to the gages?

Ol' Ron · 05-18-2015, 07:30 PM

Painless wiring has a module for the 6V instruments. Drops the 12 to 6V

Sid the Maineiac · 05-18-2015, 07:51 PM

NAPA has a Voltage reducer part #vt6187, I believe these were used on late 50's Fords.Won't hurt to call!

4ford · 05-18-2015, 08:28 PM

what kind of alt do you have? voltage reg? and yes the voltage reducers are a must

AnthonyG · 05-18-2015, 09:05 PM

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If you didn't use a 12V to 6V resistor/reducer on all requiring 6v then you probably fried or damaged everything requiring 6v. You needed a 12 V coill & light bulbs, & any gauges or electric motors like your heater blower, using electric would need the voltage reducer You will be okay with the amp gauge if it's what you're calling your charging gauge as amps are amps 12V or 6V doesn't matter as long as you didn't change the wiring and run it thru the wrong direction. If so it will register backwards. if your starter is 6v no prob it can take the 12v and it will run twice as fast wich will start your engine great.

35 coupe · 05-18-2015, 09:16 PM

I did my 50 f1, put a Runtz diode on all gauges, got them on epay and they come with instructions not hard to do, go on positive side of guage one for every guage, 10 to 12 bucks each

Drbrown · 05-18-2015, 10:25 PM

You didn't say .... did you also change your system to negative ground ?

wga · 05-19-2015, 07:28 AM

Search 12v conversion on this site.

Cecil/WV · 05-19-2015, 07:46 AM

The mistake was changing it to 12v.

bchrismer · 05-19-2015, 08:16 AM

Joe,

I'd hate to even guess, based on the opening post. Without telling more about "what" you have done, and "how" you did it, everything else is just a guess.

I'd love to help you figure it out, but I would need to know more about the "what and how" of your 12v conversion.

Here's a page that I used, somewhat as a guide, when I did a total rewire of my '40 stake truck. http://www.oldengine.org/unfaq/six12.htm

19Fordy · 05-19-2015, 09:01 AM

Joe, The first thing I did was install a CVR from Ron Francis. That allows the gauges to still operate on 6V. Then to make the BATT gauge function properly I isolated it from all the other gauges and installed a resistor in the 12V wire that feeds it so the 12V voltage would be reduced to 6V. In a 40 Ford the BATT gauge is a voltmeter, not an amp meter. Check out posting #6 here.
https://www.fordbarn.com/forum/showth...olt+conversion

Mike51Merc · 05-19-2015, 09:37 AM

Call me crazy, but as far as I can see you haven't described anything wrong. Temp gauges are normally to the right on "H" when shut off, unlike a fuel gauge which goes to the left to "E".
The "charging gauge" ammeter should be in the middle when running and slight discharge with lights on.

JSeery · 05-19-2015, 01:08 PM

Nothing from the original poster after the first post!?

chap52 · 05-19-2015, 01:14 PM

That ammeter gauge has a "very slight" movement. But you will need a voltage reducer as advsed above.

Mike51Merc · 05-19-2015, 01:50 PM

Quote:

Originally Posted by chap52

That ammeter gauge has a "very slight" movement. But you will need a voltage reducer as advsed above.

Ammeters don't get voltage reduction in any case.

V8COOPMAN · 05-19-2015, 01:54 PM

Quote:

Originally Posted by Mike51Merc

Ammeters don't get voltage reduction in any case.

Fact! DD

supereal · 05-19-2015, 04:03 PM

Ford gauges are operated by a heating element that surrounds a bimetal strip. If the voltage isn't reduced to six volts, the gauges will be destroyed in a short time. As said above, the '40 used a voltmeter, not an ammeter, so a series resistor must be used to place the needle in the green section. If the deflection of the gauge is large, place a voltmeter across the battery and watch the level under load, such as headlights, to see if the generator or alternator output is sufficient, and the regulator is working.

05-18-2015, 05:52 PM	#1
joedaless Member Join Date: Jun 2010 Location: Clinton Connecticut Posts: 41	I changed to 12 volt Hi All, I recently changed to 12 volt on my 41 Ford Coupe. I now have a non working sending unit. My heat and cold gauge now when I shut the car off goes all the way to H when it is off. The charging gauge stays right in the middle when running . When I put the lights on it is discharging a little bit. Can anyone tell me what I did wrong. Me and the electrical parts on my antique cars never got along. Any and all help will be very much appreciated. Thanks , Joe D

05-18-2015, 07:30 PM	#3
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,985	Re: I changed to 12 volt Painless wiring has a module for the 6V instruments. Drops the 12 to 6V

05-18-2015, 07:51 PM	#4
Sid the Maineiac Senior Member Join Date: May 2010 Location: Norridgewock,Maine Posts: 657	Re: I changed to 12 volt NAPA has a Voltage reducer part #vt6187, I believe these were used on late 50's Fords.Won't hurt to call!

05-18-2015, 08:28 PM	#5
4ford Senior Member Join Date: Jun 2012 Location: Eagan mn Posts: 132	Re: I changed to 12 volt what kind of alt do you have? voltage reg? and yes the voltage reducers are a must

05-18-2015, 09:16 PM	#7
35 coupe Senior Member Join Date: May 2010 Posts: 373	Re: I changed to 12 volt I did my 50 f1, put a Runtz diode on all gauges, got them on epay and they come with instructions not hard to do, go on positive side of guage one for every guage, 10 to 12 bucks each

05-18-2015, 09:05 PM	#6
AnthonyG Senior Member Join Date: May 2013 Location: Pa. Posts: 2,217	Re: I changed to 12 volt Sponsored Links (Register now to hide all advertisements) If you didn't use a 12V to 6V resistor/reducer on all requiring 6v then you probably fried or damaged everything requiring 6v. You needed a 12 V coill & light bulbs, & any gauges or electric motors like your heater blower, using electric would need the voltage reducer You will be okay with the amp gauge if it's what you're calling your charging gauge as amps are amps 12V or 6V doesn't matter as long as you didn't change the wiring and run it thru the wrong direction. If so it will register backwards. if your starter is 6v no prob it can take the 12v and it will run twice as fast wich will start your engine great. __________________ Nomad Last edited by AnthonyG; 05-18-2015 at 09:56 PM.

05-18-2015, 10:25 PM	#8
Drbrown Senior Member Join Date: Oct 2013 Location: Glens Falls NY Posts: 1,355	Re: I changed to 12 volt You didn't say .... did you also change your system to negative ground ?

05-19-2015, 07:28 AM	#9
wga Senior Member Join Date: Jul 2010 Location: Yorba Linda, CA Posts: 962	Re: I changed to 12 volt Search 12v conversion on this site. __________________ Henry Ford designed the flathead without the aid of a computer.

05-19-2015, 07:46 AM	#10
Cecil/WV Senior Member Join Date: May 2010 Location: Gerrardstown, WV Posts: 2,298	Re: I changed to 12 volt The mistake was changing it to 12v.

05-19-2015, 08:16 AM	#11
bchrismer Member Join Date: Apr 2011 Location: Springfield, MO Posts: 77	Re: I changed to 12 volt Joe, I'd hate to even guess, based on the opening post. Without telling more about "what" you have done, and "how" you did it, everything else is just a guess. I'd love to help you figure it out, but I would need to know more about the "what and how" of your 12v conversion. Here's a page that I used, somewhat as a guide, when I did a total rewire of my '40 stake truck. http://www.oldengine.org/unfaq/six12.htm __________________ HotRodHundred.com Reliability Runs It's about the drive!!! StreetRodder.Net The FUN is in the RUN!!!

05-19-2015, 09:01 AM	#12
19Fordy Senior Member Join Date: May 2010 Location: Coral Springs FL Posts: 11,604	Re: I changed to 12 volt Joe, The first thing I did was install a CVR from Ron Francis. That allows the gauges to still operate on 6V. Then to make the BATT gauge function properly I isolated it from all the other gauges and installed a resistor in the 12V wire that feeds it so the 12V voltage would be reduced to 6V. In a 40 Ford the BATT gauge is a voltmeter, not an amp meter. Check out posting #6 here. https://www.fordbarn.com/forum/showth...olt+conversion Last edited by 19Fordy; 05-19-2015 at 12:11 PM.

05-19-2015, 09:37 AM	#13
Mike51Merc Senior Member Join Date: May 2010 Location: Northeast Pennsylvania Posts: 1,582	Re: I changed to 12 volt Call me crazy, but as far as I can see you haven't described anything wrong. Temp gauges are normally to the right on "H" when shut off, unlike a fuel gauge which goes to the left to "E". The "charging gauge" ammeter should be in the middle when running and slight discharge with lights on.

05-19-2015, 01:08 PM	#14
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: I changed to 12 volt Nothing from the original poster after the first post!?

05-19-2015, 01:14 PM	#15
chap52 Senior Member Join Date: Jun 2013 Location: Marana Arizona Posts: 1,829	Re: I changed to 12 volt That ammeter gauge has a "very slight" movement. But you will need a voltage reducer as advsed above.

05-19-2015, 04:03 PM	#18
supereal Senior Member Join Date: Jul 2014 Location: Iowa Posts: 1,634	Re: I changed to 12 volt Ford gauges are operated by a heating element that surrounds a bimetal strip. If the voltage isn't reduced to six volts, the gauges will be destroyed in a short time. As said above, the '40 used a voltmeter, not an ammeter, so a series resistor must be used to place the needle in the green section. If the deflection of the gauge is large, place a voltmeter across the battery and watch the level under load, such as headlights, to see if the generator or alternator output is sufficient, and the regulator is working.