Mea culpa. I didn't see the rear filler cap when I looked at your pictures. You are correct: With the dual-chamber fuel tank, the starting tank (smaller chamber, for gasoline) is an integral part. Once the engine was warmed up, it could be run on kerosene (from the larger chamber of the main tank). The earlier-style auxiliary starting tank (cast-iron, approx. 1-gallon capacity) is not needed, and so it was removed.
Now you have another reason to look up the serial number: The dual-chamber fuel tank was not introduced until June 1924, so the fuel tank is either a replacement, or the tractor was manufactured later than 1923. (Go here
to see a diagram of the serial number location. )
It's difficult to get a picture of the commutator installed, as there is so little room between the front of the engine and the radiator. This is a very common part (the identical part was used on Model T automobiles), so yes, they are available. The commutator, also known as the timer, is a common tune-up part. You'll need new wires and the linkage (assuming that it's missing and not sitting atop the crankcase, loose) that connects the spark lever to the commutator (this advances or retards the spark, as mentioned above). Follow the link in my previous posting to go to The Fordson House's web site; they have everything you need, and you can also see the associated pieces and parts of the commutator assembly.
Keep an eye out for a Fordson owner's manual on eBay; sometimes you can find one for $10 or so. There are folks on this site who sell them for $45, but I'm pretty sure you can find a copy cheaper than that. This manual will show you all of the parts of your tractor, plus exploded diagrams, plus maintenance requirements -- all of which are very helpful when you are working on something this old.
If you go to flea markets or swap meets, you'll likely find parts much cheaper than if you shop on-line.
-- Maine Fordson This post was edited by Maine Fordson at 11:25:28 08/21/10 4 times.