Recently, however, the Research Center at the Henry Ford Museum & Greenfield Village located a substantial amount of material which has opened new vistas in the evolution of the Model T Ford. Included in this material are some, but not all, of Ford's account books covering this period. These books contain the name of the dealers, what they bought, when they paid, and the dates and serial numbers of the Model T's they purchased.

Of course the date of sale to a customer is not necessarily the date the engine (or the car) was assembled, but generally it is quite close. Unfortunately, for us, Ford did not assemble engines to chassis and chassis to bodies in a strict numerical order so there are cases where the serial number versus the sales date is quite different from the actual date of engine manufacture. However, as in the 1909-1911 data published in the Model T Encyclopedia and the Model T Ford books, at least we have a ball-park figure far more accurate than the figures Ford published during the Model T era.

Even more interesting is the uncovering of the "B"-numbered engine information contained in the dealer account books. Previous literature has mentioned the fact that Ford made 12,247 B-numbered engines "during fiscal 1913 in Detroit." Apparently these engines were built in the late summer and early fall of calendar 1912 and seemed to have gone into the bulk of the cars assembled between October January 1913 (1913 models). It also seems as though these engines were placed in a pile and were installed in a chassis in a random order, apparently whichever number was easiest to take off the stack.

Ford's engine production records indicate that the first engine serial number in fiscal 1913 (October 1, 1912) was 157,425. Early in October 1912 the B-numbered engines began and the standard serial numbers vanish from the books. (We examined just seven of the accounts receivable books, with over 2200 cars between September 1911 and 1914 listed, so we can't give an exact date for the last standard-numbered or first B-numbered engine.) Once in a while during this period a "standard" number appears but most are B-numbers until late November 1912 when the standard numbers resume, mixed with the B's.

Data for 1912 is further confused by the significant number of engine numbers listed in the early months of that year which are out of numerical order. Serial numbers as low as in the 86,000 range are mixed in with numbers as high as in the 113,000 range between January and April 1912.

Those of you who have read the serial number data in the above-mentioned books might remember that the serial number data for 1913 and 1914 had not been found but that the daily production figures were available, and that the serial number data for those years was derived from those production figures. Somewhere along the way we came out just one number off over the two-year period due to an error somewhere in the available data (either the starting or finishing serial numbers were wrong or the production figures were wrong).

One engine number off didn't seem like a major problem but the 300,000^th engine number was. Ford records show the 300,000^th engine as having been built on July 16, 1913 while our serial number list put it on June 26. There is a difference of approximately 12,000 engines between these two dates.

During the B-number era the use of the B engines began at somewhere in the 157,000 range. When the standard numbers reappeared they seemed to have begun in the 169,000 range; a difference of about 12,000. It would appear that the B-numbered engines replaced the standard numbers and that there were no serial numbers in the 158,000 to 169,000 range. This hypothesis seems to agree with the probable production figures of that time period.

So, what about the 300,000 date problem? This writer's bet is that the engine department kept a count of the engines, not the serial numbers, If the B-numbered engines were built elsewhere, the 300,000^th engine built at Highland park would have been on July 16 but that engine would not have been the one with a serial number of 300,000.

To back up this hypothesis, we recorded sales dates during 1913 and found that all serial numbers were sold in the range of our serial number data. Engine number 300,101, for example, was sold on June 26, 1913. Many engines with numbers in the 300,000 range were also sold on that date. It is obvious that number 300,000 was built before July 16.

So there you have it. Unfortunately we were only able to sample a small part of the information in the account books, and not all of the accounts receivable books exist, so there are gaps in the available information.

Following are the data that picks up where the Encyclopedia and Model T books are vague: October 1911 to January 1913.

Note that the serial numbers are not in numerical order. It appears that engines were built and placed in a storage area, and were then selected at random for installation in a chassis. Sort of a "first in, last out" situation, particularly when it came to the "B" numbers. The "B" engines were built at another plant in Detroit and were shipped to the assembly point, so it is easy to see why they were not used in a numerical sequence.

Data compiled from Accession 623, "Accounts Receivable, 1904-1914," at the Research Center, Henry Ford Museum and Greenfield Village.