I'm currently cleaning up a mustang gas tank install in my 56 F-100. Thing is I didn't follow the tech article directly. I mounted it up from the top part of the frame so it is more tucked up into the frame rail. What I forgot to notice was that the fuel inlet on the tank is not exactly in the center, so when putting the marine deck filler in you need room for hose to bend to both parts (I have only half an inch between the two). And second, most marine deck fillers take a smaller hose diameter than the tank fuel inlet. So I'm thinking about cutting out the original fuel inlet in the gas tank and weld a smaller diameter metal tube in the center. In that case I can use one size hose and go straight down. My question is will I be able to do this cutting and welding to the tank and be able to use it right after, or should I clean it out thoroughly before I use it (the gas tank is brand new so I'm just worried about metal shavings) Thanks

Craig

 

Craig,
you'd definitley want to clean it out good first.
I mounted mine the same way in my 55 but for that reason,I went with a fold up door(door is centered but filler isn't).Another "situation" I came across was that the metal brace that holds the box boards hit the tank so I had to build a new brace.
Greg

 

So I modified the tank and it fills fine and supplies the engine just fine. Now when I hooked up the sending unit it read as completely full even though there was only 1.5 gallons in it. My truck is converted to a 12 volt system and still has the original dash cluster so I'm assuming I have to do something with the the sending unit. Any help would be greatly appreciated.

Craig

 

The sending unit may be okay. Many Fords use the same resistance. If you converted to 12 volts and are still using the original gauges, you need a voltage drop resistor for the fuel gauge. Perhaps when you drop the voltage on the gauge back to six volts, the gauge will read correctly. If that doesn't work, then you could go with an aftermarket fuel gauge...just be sure you get one for a Mustang sending unit.

 

So I'm curious, when these trucks are converted from 6 to 12 volts, do people run the guage wiring through a voltage damper of sorts so they work with the original dash cluster? Or is everything changed in another way

 

Obviously, mechanical gauges work fine on 12 volts, like oil pressure and water temp, so all you need to do with those is change the bulbs. The ammeter doesn't care whether you feed 6 or 12 volts through it. But, things like gas gauges, radios, heaters, electric wipers, or gauges using electrical sending units have to either be changed out to 12 volts or the voltage reduced to 6 volts by a resistor of some type. Many years ago I used an ignition ballast resistor to cut the voltage to my gas gauge on an old Chevy and it worked out fine. I figured if it cuts the voltage to the points to six volts, then I could use a feed off of it for my gas gauge...plus they are cheap and easy to find. If you do use a ballast resistor, be careful how much load you put on it because I'm not sure how much it will take. I wouldn't run a heater or an original vacuum tube radio off of one for example, because those components take a lot of current.