1955 ford Ranchwagon Fuel sending unit

[poolplayer1]

I had ordered a universal fuel sending unit and also a 12 volt fuel gauge for this car.The sending unit works on eighter 6 or 12 volt,according to them.I went ahead and replaced both and also put 10 gallons of gas.10 gallons is about half tank on this car. I checked the fuel gauge and it reads full.
This is not right.I really think the problem is the sending unit. It came with instructions and tells how to cut the float arm according to the depth of the tank. I did all that and still does not read correct. My old sending unit was all corroded and the fuel gauge needle was broke.Has anyone here bought a sending unit and gauge that worked on their car? I converted my wagon to a 12 volt system.Or,if I find the origional 6 volt sending unit and 6 volt gauge,I can use them.I'll just put in a dropping resistor to go from 12 to 6 volts.
Thanks to all for your help with this problem.
PS- The fuel tank was empty when I put in the 10 gallons of fuel.

 

[dmsfrr]

Is the shape of the 'wagon' tank different somehow? Is there a way to try adjusting the float arm that can be undone if it doesn't correct the gauge reading? If it can, just experiment.

IF the original gauge and sender are still functional they aren't really voltage sensitive. The old King-Seely type gauges don't work the same as newer setups.
Look at the diagram below and you'll notice they function on heat, with bi-metal strips doing the work. They can sometimes be repaired.

The info at this link was written for converting 6v '55 T-Birds to 12v but nearly all of it will apply to your '55 Ranchwagon.
https://www.ctci.org/battery-for-6v-to-12v-conversion/
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[Daves55Sedan]

The instructions that came with the unit are obviously generic.
I suggest focusing upon how far out the float is from the center of the sending unit pivot point. Notice how the float aims toward the back of the tank and is allowed to rest in a shallow well at the bottom when the tank is empty, and the float bobs up into an identical well at the top of the tank when full.
Your adjustment for the length of the float arm should reflect those intended targets.
Another thing that will affect fuel level reading at the guage is if the tank is actually level or if it is tilted.
The back of my '55 wagon is tilted upward such that the front of the tank is lower than the back of the tank. This is real bad because since the float aims toward the rear of the tank, there is actually very little movement of the float arm between empty and full.
To some degree, the float arm can be adjusted to compensate, but it will never reflect the actual fuel level properly.

 

[40cpe]

If you replaced the fuel gauge with a Ford unit you probably won't get it to read accurately through the range using an aftermarket sender. About all you can do is adjust it to tell you when the tank is about empty. I have a '55 using the stock gauge and an aftermarket sender. It reads empty when the tank is empty, but if I put more than 7 or 8 gallons in it it goes to full. I would drain yours down to empty and see where the gauge reads, and then adjust to empty with two gallons in it. Then add two gallons at a time to see how each stage affects it.

 

[poolplayer1]

Thank you very much guys for your good advice.I am going to do a trial and error on float arm to see if I can get it adjusted to read at least close enough. I wouldn't mind if the reading is off by a quarter tank but not much more than that.
Thanks dmsfrr for the link.I will go there and read up on it.