Fuel Gage - volatge senstive?
 

I really don't want to scratch the 6v versus 12v scab, but here we go.
Does the fuel gage even care about volatge? It seems to me that it shouldn't. Both the sending unit and the gage are basically variable rehostats. I did the conversion on my 40 deluxe and need to do the dash next. I've read many posts about the conversion and using voltage reducers, it has me wondering.

Re: Fuel Gage - volatge senstive?
 

Yes, it does.

They are not variable rheostats at all. They operate on the principle of differential heating. There are bi-metallic strips (a strip of metal with two different kinds of metal on each side bonded together that have different coefficients of expansion). When heated, they bend and when bent, produce a different tension required to move.

Pick up a Ford Service Bulletin - it explains the operation well.

Bottom Line: You need 6V to the gauge for it to operate properly. You can get close with a dropping resistor, but I'm of the opinion that the gauges work much, much better and far more accurately with a constant voltage regulator. The 7806 CVR produces 6V output with an input of 10-18V or thereabouts. This gives far more accurate gauge readings than even the stock 6V system because the voltage is steady and constant. You need one per gauge - although different CVR will have a higher output current and can run all three gauges - oil pressure, water temperature, and fuel gauge. These are cheap enough (<$.50/each) to run one for each gauge and keep a spare or two in the toolbox.

Your voltage gauge requires a dropping resistor of approximately 60 ohms. You need to use an accurate, precision, wire-wound resistor of exactly 60 ohms for this purpose. The el-cheapo radio shack carbon resistors are not nearly accurate enough to use for this and the precision resistor will only cost a few dollars at most. This will put your "green band" right at about 13.5-14V on your gauge.

Re: Fuel Gage - volatge senstive?
 

Do you have a good source for the 7806 cvr?

Re: Fuel Gage - volatge senstive?
 

No, you don't need three. I've been running all three gauges in my '53 on one 7806 for years and it hardly even gets warm using a simple heat sink.

The photo shows two 7806 regulators; the second one was for a 6-volt tach I was using back then. It has since been disconnected.

Re: Fuel Gage - volatge senstive?
 

I'm building a complete new 12 volt system in a 40 standard now. I bought the 12 volt conversion guide booklet from Drake. It is written by Fifth Ave Antique Auto Parts in Clay Center Kansas and is quite complete and thorough. They reccommend their "Runtz" voltage drop ( approx. $18 each ) for all the instruments but the volt guage. They reccommend having the volt guage converted to 12 volt which I am having done now at ADT Instruments Intl. Inc. in Bloomington Minn. They restored the complete cluster as well.

John

Re: Fuel Gage - volatge senstive?
 

Use of a 7806 requires some fabrication and is available here----

http://www.ebay.com/sch/i.html?_nkw=...tage+regulator

as well as other places.

You can get a ready made regulator here.----

http://macsautoparts.com/early-v8-voltage-reducer-reduces-12-to-6-volt-v12871/camid/F30/cp/340RW35U1000017/

Re: Fuel Gage - volatge senstive?
 

Here is one from Vintage Auto Garagehttp://ep.yimg.com/ca/I/yhst-1746754...216_900079.gif

Re: Fuel Gage - volatge senstive?
 

This will also be helpful re: volt gauge conversion.
http://www.fordbarn.com/forum/showth...olt+conversion

Re: Fuel Gage - volatge senstive?
 

Here is another one that wont break the bank, it does all your gauges, you only need one.

http://www.ebay.com/itm/271008367259...84.m1586.l2649

Re: Fuel Gage - volatge senstive?
 

You can also use a stock one for a 57 to 59 Ford. They work great.
Butch

Re: Fuel Gage - volatge senstive?
 

Yes, you can get by with one, but you're running pretty close to max capacity for it. These things are super cheap, so the extra $.50 to get two more will hardly break the bank...A good heat sink, which it appears you have, helps a lot though.

The Runtz is expensive and is just a resistor. The voltage output varies with the voltage input and current through it. It is a poor choice for gauges, although they do work satisfactorily for most folks.

By "volt gauge", are you referring to the "Batt" gauge on a '40? If so, a precision 60-ohm resistor is all you need to "convert" it. No changes or alterations to the gauge itself.


The factory (instrument reducer) IR is a chopper style. It works too, but again, is a poor choice for gauges, IMO. For original style gauges that used a chopper, it works fine. And will probably work satsifactorily for most folks too, but it's not the most accurate thing in the world and if you buy it new at NAPA (vs scrounging in a junk yard), they're expensive.

Re: Fuel Gage - volatge senstive?
 

A Ford B9MZ-10804-C or NAPA IR1 regulator works perfect and supplies a 6 volt pulsed signal to the gauges. It is a stock ford art for 1959 and I have used them many times with excellent results.

Re: Fuel Gage - volatge senstive? CVR Explnation please
 

Ok what is the "C" in CVR

C=?
V=Voltage
R=Reducer

a little slow this AM :eek:

THANKS

:)

Re: Fuel Gage - volatge senstive? CVR Explnation please
 

Constant
Voltage
Regulator

Re: Fuel Gage - volatge senstive?
 

Many people do use them with good success. However, it's a poor choice for gauges, despite being an OEM part (my opinion from an electrical/electronics perspective only - nothing more - take it for what it's worth (exactly what you paid for it)). The chopper or pulsed signal cannot provide the most accurate reading. Accurate enough? Probably. But they're $30 (unless you scrounge one in a junkyard) and the CVRs are pennies. New technology. Sometimes it is better. ;)

Re: Fuel Gage - volatge senstive?
 

51 MERC-CT
Let's see I got one out of three correct thats 33 1/3 % Correct.
that's about the same test scores I got in High school. LOL LOL

THANKS
now if I can just remember where I file this it will be Ok.

Re: Fuel Gage - volatge senstive?
 

I was unaware that the fuel gage and sending unit are bi-metal units. I would appreciate a more complete explanation of how they operate. Does the Drake sending unit use a bi--melal strip also?

Re: Fuel Gage - volatge senstive?
 

Check this out : https://forum.hetclub.org/uploads/Fi...de0f4d6d0a.pdf.

Re: Fuel Gage - volatge senstive?
 

Derby, here's a post that will answer your question. It tells how gauge and sending unit work on the bi-metallic principle. Scroll to #4.
https://www.fordbarn.com/forum/showt...k+sending+unit

Re: Fuel Gage - volatge senstive?
 

Many thanks. Just what I needed!

Re: Fuel Gage - volatge senstive?
 

I am starting on gauges for our '40 pickup. I've read a lot of posts on this subject, so I think I understand most of the issues. I will have to use an aftermarket gauge, since the original will not fit into the new tank. I've gotten a couple of sending units recommended here (Carpenter and Yogi's). I've also gotten some of the MC7806 voltage regulators ($0.39 each). I've got 4 different gauge clusters, but most sat out in the weather and look nasty. I need a good working gauge to figure out how to adjust the sending unit arm length and height. How can I test these gauges to find one that works? Can I briefly touch 6v across the contacts to see if the needle moves? When they don't work what is normally the problem and how do you fix it?

Re: Fuel Gage - volatge senstive?
 

Use a 1.5 volt battery and you should get a half scale reading

Re: Fuel Gage - volatge senstive?
 

I played with several gauges today. With the face off, the oil pressure and fuel gauge appear to be identical. The temperature gauge appears to be a mirror image. All measure about 10.5 ohms through the windings, however, the needle doesn't move with 1.5 volts. So I still don't know whether I've got any good gauges, but the consistent 10.5 ohm measurement suggest they should work. Any ideas?