Reposted from a similar previous discussion located at:
http://www.mtfca.com/discus/messages/50 ... 1423792688 by me (Hap l9l5 cut off):
I believe the evidence supports that the date listed in the USA engine logs from Jan 1915 to 1927 is usually not the date the car was assembled although in some cases it was. And it is not necessarily the date the engine was assembled if the engine was assembled outside of Highland Park and later River Rouge plants. (And there was a transition period when Highland Park sent engine numbers to the River Rouge as they began engine production and later River Rouge sent engine numbers to Highland Park as HP began ending engine production.)
1. Please remember that the date listed in Bruce McCalley's (R.I.P.) serial number listing which is the normal reference we use for USA produced engines is the date the engine number was entered in the USA Ford Motor Company daily log books of the engine assembly department starting in Jan 1915 and continuing to 1941 (ref page 501 and 537 of Bruce's book "Model T Ford").
2. The date entered in the engine production log is not necessarily the date the engine was assembled. On that same page 501 Bruce states, "During the Model T era, great numbers of engines were assembled at the Ford branches. Apparently Ford printed engine number job sheets which were numbered in advance, and these were attached to engines being assembled. These job sheet numbers were stamped into the cylinder block when the job was completed. [Hap's comment: only complete engine & transmission assemblies received a serial number -- not a short block. Although replacement blocks would be stamped with the serial number of the engine block they replaced if the swap out was done by an authorized Ford Agency (dealer) and they followed Ford's guidance. Now back to Bruce.] Groups of these engine number records (not engines) were also shipped out, and these numbers were then stamped on the engines when they were completed at some Ford branch. Some of these record number shipments were noted, but most were not. As a result, while the Highland Park (or, later, the Rouge Plant) assembled engines on the days indicated, other blocks of engines might have been assembled days or weeks later.
3. It is possible that an engine that was assembled in Detroit might also have been installed in a car on the same day the engine was assembled. Especially if the engine was assembled early in the day and the car later in the day and both at the same location i.e. Highland Park. But that would probably only happen at the main plant location in Detroit when engines were not being shipped or not being shipped very far. In most cases when engines were shipped the transit time for use at the other location would be a few days minimum. I believe this is illustrated by the note at:
http://www.mtfca.com/encyclo/doc25.htm which states:
DEC 12, 1925 Acc. 94. Walter Fishleigh files, Ford Archives
"Motor number was first placed on frame side member R.H. on Dec. 12, 1925. Motor No. 12,861,044. Information obtained from Mr. Burns, Final Assy., Highland Park."
But if we look up the engine serial number 12,861,044 we note that it is listed along in the group from 12,855,160 to 12,863,164 under the date of Dec 5, 1925. In this case the engine was assembled at the River Rouge engine assembly plant (ref 532 shares that production completely shifted from Highland Park to the River Rouge with the last recorded/noted engine numbers (62 numbers -- not engines) sent on Feb 13, 1925 to Highland Park to be stamped on engines assembled there. So in this case it took from Dec 5, 1925 to Dec 12, 1925 for the engine to travel from the assembly plant at the River Rouge to the assembly plant at Highland Park to be dropped into a chassis. That's 7 or 8 days depending on how you count but clearly not the same day of the engine log entry. And note that engine did not have to leave the city.
Note engines could be sent from the River Rouge to the Highland Park plant quicker. On page 536 they note that engine #14,999,999; 15,000,000; and 15,000,001 were held out of production on May 25, 1927 for the next day. And other sources show the 15,000,000 Model T with that engine rolled off the assembly line on May 26, 1927. But I suspect those three engines did not take the normal trip from the River Rouge to the Highland Park plant.
4. And what were the odds that your T was assembled at Highland Park? That varies by year. In 1925 Ford Motor Company USA recorded a total of 1,775,245 Model Ts (includes chassis, cars, and trucks) with 111,418 assembled at the Highland Park plant (ref page 468). That is approximately 6.28 percent of the USA Model T production were assembled at the River Rouge. That year the only plant that assembled more Ts than Highland Park was the Kearney plant with 137,321 assembled.
5. And in some cases engine were stored and installed in cars later. For example the note at:
http://mtfca.com/encyclo/doc24.htm the Mar 18, 1924 entry reads:
"We hear stories that some salesmen are telling their customers to be sure and look at the motor number of any car when they buy in order to be sure they get a late motor number. These particular salesmen are just making a lot of trouble for themselves because at the new plant we have hundreds of motors that have been standing there for thirty days or more and will be going into the cars in the course of production. This means that all dealers will receive motor numbers from the Burnham plant that will be considerably lower in number than those motors received from the Chicago plant so just stop your salesmen making any remarks at all about motor numbers because in so doing they are going to make a lot of trouble for you when we start shipping from the new plant."
A.W.L. Gilpin
Branch Manager
P.S. In correspondence the old Ford plant in Chicago is referred to as the Chicago plant and the new plant is referred to as the Burnham plant because it is near the Burnham railroad yards.
Finally is some cases the engine records record the actual time an engine was assembled -- usually the milestone engines such as:
1,000,000 on Dec 10, 1915 at 1:53 1/2 P,M. ref page 512
5,000,000 on May 28, 1921 at 7:05 A.M. "to Edsel Ford"
10,000,000 on Jun 4, 1924 at 7:47 A.M.
Respectfully re-submitted,
Hap l9l5 cut off
But you are darn close, it was June 26, 1924. Ford numbers show 8102 for the 26th and dropped to 2040 on the 27th.
, I don’t know that date. July of 13 seems early for a 14 model year. I have 4 transmission shafts on the shelf with no date so I couldn’t say how long they did that. 
