The pictures don't show it all, but most of the process. Some of the things like trimming out the cork and putting in the metal sleeve are not shown. I'll try to suppliment with text as we go.
Most of us have seen the big brother version gas gauge meant for larger Farmall tractors such as this:
My Simplicity lawn tractor has one, but that IH picture inspired me to start doing some thinking (on paper) about how to make one for a Cub:
1 large cork (outside diameter at large end exceeds 1" diameter)
1 replacement gas gauge
1 plumbing slip joint (1-1/4")
a piece of glass (cut to fit inside the cap of the slip joint)
a piece of sheet metal (weldable, 16 ga +/-)
cork sheet gasket material
two metal bars (stiffeners from a discarded windshield wiper blade)
Get your 1-1/4" slip joint from the home improvement or hardware store. Disassemble and cut the body about 3/4" from the top:
Cut the sheet metal into a disc and fit into the slip joint body. You'll be welding it about half way up into the body (enough head clearance between it and the underside of the glass for your needle to rotate). Now you have your cap, disc, cut slip joint and metal bars:
I drilled my cap and disk/top separately, but on second thought, it might be better to weld the disk/top to the top of your cap first, then drill your hole. I'll show you how I did it and you can do as you please:
Take one of the metal bars from the wiper and drill a small hole (1/16"-5/64"+/-). Just don't drill to the outside edge, it must be a complete hole. Make a mark 1/2" on each side of the hole:
Bend the metal bar as shown at the 1/2" marks and then again at 7-1/2" from the bottom to form feet:
The first gas gauge I made utilized bent metal bar, cutouts for two small screws to attach the metal bar to the cap. But here, I cut a scrap piece of sheet metal and used it to sandwich the feet of the metal bar to the underside of the cap w/ screws (drilled/tapped). It seemed nice and secure when done:
Take the other metal bar and cut the pivot point checking often with the drilled hole for fit:
At this point, I ground off the paint from the cap and welded the top to it using a spacer rod to center the top in place:
Welding brass is not fun. I blew holes through it where not intented. But, I wanted holes for air circulation anyway since the top is covering the two holes in the cap. Need to keep air able to move in/out. Here's the center metal bar cut to length running up through the cap (about 1/2" +/-) taller than the face of the dial:
Cut the glass to fit:
Now, you have the metal frame at 1" distance evenly from top to bottom. Cut two grooves in the sides of the large cork. Drill out a 1/4" +/- hole from the bottom of the cork to the top but don't penetrate the last 1/4". In other words, you'll have a slot cut down through the first 1/4" of the large cork, then it transitions to the 1/4" diameter hole in the bottom. In that slot bend and place a piece of thin sheet metal, tight to the cork (so it won't come out) but with enough clearance to the twisted bar so the cork freely slides up/down along the metal frame.
Twist the rod so when the cork is at the bottom, it's pointing to where you want Empty to be; when the cork is at the top, where you want Full to be. This is largely your preference. I made a dial on the computer and had it copied off at Office Depot or some such store onto oil resistance paper. Here's what we have so far:
Paint the cap:
I cut two cork sheet gaskets to sandwich the glass under the cap ring. Glue in the dial:
Install and enjoy:
DISCLAIMER: The first one I made has been on my '48 for a year. The dial face shows some signs of yellowing, but otherwise seems to be working fine. This whole project was motivated by me NOT using hardener in my paint on the hood. Not wanting to unnecessarily open my gas cap, I chose to make a gauge so I'd know approximately how much has was in the tank. You may find that lengthening or shortening the metal frame suits you better. The 7-1/2" metal frame seems to work well for me.
It was a fun project, but it had times of frustration and challenge. Enjoy.