If your truck has a manually operated fuel tank selector VALVE located on the floor, you have a factory installed and an aftermarket fuel tank.

1975/79 F100/350 with factory installed dual fuel tanks has a fuel tank selector valve & solenoid assembly mounted on the cross member.

The selector switch located in the heater control panel changes the tanks and the dash fuel gauge from one tank to the other.

 

If you have the center screw out, you might spray some penetrating lubricant in there to break up any corrosion or just old-age gluing things together.
In theory, unless it's different from the stuff I'm used to (which is very possible) then the handle/lever/thingy should pull right off the splined shaft. I think you're right not to try to force it though. It's not too weak of a thing, but who knows what the last forty years or so have done to it.
I'm not sure if it's possible to remove the switch assembly without removing the lever, but if the hole in the floor is large enough, maybe you can still get it out.

Is this just for the carpet installation though? If so, why not just leave it in? Does the carpet go under the face-plate or something like that? Maybe just loosening it up will help.
Sorry if any of that was way off base. I've seen the valves in discussions here before, but it's been awhile and I don't remember all the details.

Good luck.

Paul

 

There are typically two small bolts (7/16" I think) that hold the valve to the floor. If you look underneath the truck you should see the nuts on the underside. The bolt heads could be hidden under carpeting. Once you remove the bolts you should be able to tap the whole unit from the top to get it out.

 

 

Are you using a Windows computer for all this? If so, search "power toys" or "power toys for win 10" and you should be able to find what you need.
You can re-size images in the standard Microsoft program (the name escapes me at the moment, but you will know it when you see it. Paint maybe?) but the image resizer in the Power Toys program/app is great.
With it you can simply right-click the image and it gives you multiple resolution choices right there. Click what you need, and away you go.

Good luck

Paul

 

Not to hijack the thread, but has anyone replaced the Manual valve with a solenoid valve that is wired to the dash selector switch? My sons 76 has the solenoid and factory dual tanks. My 74 F350 SCS has factory dual tanks but has a factory manual switch on the floor and a dash switch for the gage. Would be nice to convert if possible.
Garry

 

I think over the years many have done just that. I did it to my Bronco, but my '79 pickup already had the solenoid valve installed by the PO.
He said it was a 1-tank truck originally, but it did have the two doors which I guess was the norm. He installed the second factory tank with all the right hardware, used a solenoid valve and wired it to a simple toggle switch on the dash instead of sourcing a factory style A/C bezel with the switch.
I intended to do just that when I bought the truck, but I've had it thirty years now and still haven't bothered! Thanks for reminding me of something else I haven't done...

 

One easy way to reduce file size if you have a smart phone is to take the pics on your smart phone and email them to yourself. Most smart phones that I have when you email them will ask if you want to reduce them. They'll say something like small, medium, large or original size. Medium seems to work ok for me.

 

 

Now they're too small! Hah!
But we can see them at least, and that's one gorgeeeous truck!

One of my favorite color combinations in fact.

Paul