In the Model T era inner tubes came with metal valve stems. Today you can buy tubes with metal stems, or you can spend less and buy them with rubber stems. A metal stem tube costs about $10 to $13 more than a tube with a rubber stem. This makes it cost effective as well as period correct to buy metal stems and install them in rubber-stem tubes. Model T era metal valve stems can be found at swapmeets for a few dollars.

Many millions of valve stems were made, so they can often be found at swap meets. Some of these were priced at $2. Others were $3.

Sometimes you find a stem with the remains of an old tube still attached.

These are the three most common valve stems. All are made by Schrader, by far the most common brand.

Schrader #777 was used on tubes for Model T tires. It measures 3/8" by 3 1/8" (including the base).  Even though the Model T was by far the most plentiful car of its time,  this stem is  relatively scarce compared to the others.

Schrader #724 is one of the two most common stems. It measures " by
3 1/8". One side is marked with the Schrader number, and on the other side is TR-1.

Schraeder #725 is the other most common stem. It measures " by
3 ". This is the size currently used on new metal stem tubes. One side is marked with the Schrader number, and on the other side is TR-2.

Let's convert a rubber stem tube to a metal stem. The first step is to remove the rubber stem. Cut it near the base but not flush with the tube. You will find a small brass tube inside which extends down into the tube. You have to pull out the brass tube, being careful not to split the rubber tube.

Grind off the remains of the rubber stem. You want to make a flat surface that will be under the bridge washer.

Snap ring pliers are a good tool to spread the hole so you can insert the stem. Note the contact cement slathered on top
of the stem base to help seal it agtainst the inside of the tube.

Spread the hole and insert the base of the stem.

 With the stem in the hole we're ready to install the hardware.
The flat sides of the stem should be parallel to the sides of the tire.

You want an original style bridge washer with a ridge that will press into the rubber. The new bridge washers are flat on the bottom. They're no good.

Put on the bridge washer and tighten down the lock nut.

After the tube and tire are mounted on the rim, the rim washer and the dust cover go on. As the diagram shows, the rim washer is actually a nut despite the name. For brass era stems it's round and knurled. For nickel era stems it's hexagonal.

Brass era dust covers available today screw directly onto the stem.
Yes, it takes a lot of turning to put on or remove the cover. Sorry about that.

Many nickel era rim washers have separate threads for the dust cover. There are many different styles of covers and rim washers.

This is a common type of nickel era cover.

A cap inside the cover  may prevent air loss if the valve develops a leak.