Warwick,
A few things I know, things I think I know, and many more I don't know.......
The first Special racer appearance I know of occurred in February of 1910. Sometime prior to that, Henry Ford told designer Joe Galamb (Remberances) he wanted a racer built to beat the "Blitzen Benz." The big Benz came on the scene in 1909, setting world records in 1909 (England, 126 mph?), then in the U.S. at Ormond Beach in 1910 (Barney Oldfield driving) and again in 1911 (Robert Burman).
Reports indicate the first racer had a 201 cubic inch motor (racing report specs from 1910). In February 1911, two new racers raced at New Orleans at the Carnival of Speed. They had 228 cu. in. 300 cu. in. motors, and both were very successful.
This photo appeared in newspapers, beginning in early June, 1911, of the 300 cubic inch motor racer, with Frank Kulick at the wheel. I don't know if the photo was taken in the spring of 1911, or in 1910. It appears the vegetation along the track is pretty mature, so my guess is it's a late summer/early fall 1910 photo (taken at the Michigan State Fairgrounds track), but that's just a guess:
Below is a photo taken at the 1911 Algonquin Hill Climb, with a closeup of the 389 c.i. racer differential. The racer was using a 1 1/2 : 1 ratio rearend, explaining the large pumpkin. This racer, unlike the 300 c.i. above, also has external brakes, only seen in the last two 389 and 410 c.i. racers:
I know our motor matches Ford drawings labeled "M-III." There are also drawings for M (389 c.i.), M-1 (410 c.i.) M-II, M-IV and a few for M-V. There are also drawings for a "3 13/16ths engine," which I believe is the special racer sent to France in 1911.
Below is a drawing of the flywheel used on all the motors (other motor numbers listed at the bottom, cut off on this photo):
This drawing for the M-III three dip pan matches our pan measurements, as do the other M-III drawings. The last and largest M-1 motor (410 c.i.) had a four dip pan and the front wishbone was attached under the axle. This racer first raced in September, 1911, beating the Blitzen Benz in a one mile match race for time. That was Ford's last track race with the special racers. The next year the big racer went 109 mile an hour on ice, and won Algonquin Hill Climb, setting new records in doing so, beating several of the best racers in the world, including Mercer, National and others.