If my calculations are correct, the numbers on the engine block of my roadster indicates it was built the first day of March in 1920. I also realize the date the block was cast does not indicate the date the car was actually finished. To the far right of those numbers are the letters DP. If anybody knows what DP means, please let me know. Thanks

The casting date, raised numbers that are part of the casting, tells you when the block was cast. The serial number, stamped above the water inlet, will tell you the day the engine was assembled. This is usually within a few days after the casting. The assembled engine would have been put into a car within two or three days in Detroit or within a few weeks at one of the branch plants. Dunno about DP.

David,

1. Normally the letters on the sides of block are there to identify which mold was used in the casting process. That way if a casting was found to have flaws they could check the mold and either correct it or replace that mold for future use.

Caution: Additional details on serial numbers etc follows -- feel free to skip this if all you want is what the "DP" letters were there for.

2. Are you using the listing Bruce McCalley (RIP) compiled of engine serial numbers pages 501-537 in his book "Model T Ford" or his "Model T Comprehensive Encyclopedia"? If so, that is the date the serial number range was listed in the actual daily log books for the engine assembly department of the Ford Motor company from 1915 to the end of Model T engine production/assembly in 1941. As Steve mentioned normally that is the date the engine was assembled – but that is “IF” the engine was assembled at the main plant (Highland Park and later the River Rouge). If the engine was assembled at one of the branch assembly plants then the engine number was still included on the date the “range of engine numbers” were used at the main plant. But that number sent to a branch plant on that date -- and then it would normally not be the date the engine was assembled. Usually a block of 100, 200, (see page 521 with numbers (not engines) that were sent to Long Island assembly plant) and upwards to 15,000 (see page 529 15,000 numbers (not engines) sent to Manchester, England on Jun 28, 1923; again on Jul 3,1923) were sent to the branch plants that assembled engines.

3. In the case where the engine serial number was sent to a branch plant to be stamped onto an engine that was assembled at that branch it could be days, weeks, or months before the number was stamped onto a block (ref page 501 McCalley). For a more detailed explanation of the different dates etc. please see the posting at: http://www.mtfca.com/discus/messages/506218/517565.html?1423792688

4. Note also that while we do not have the break down of how many cars, trucks etc. were assembled at which branch of 1920, we do have those numbers for 1921 and later. On page 463 of Bruce’s book we see that of the 928,750 Model Ts of all types assembled in the USA during calendar year 1921, only 88,173 were assembled at the main plant at Highland Park. That is approximately 9.5% of the USA production was assembled at the main plant and the other 90.5% were assembled later at the branch plants.

5. While most of us would like to have an exact date our car was assembled, for most of us that is not documented. For the very early cars the manufacturing date is recorded up to around car# 70,700 or so ref page 499 of Bruce’s book. And there are also shipping dates for 15-20% or so of the cars from then to the beginning of 1915. So what does the engine serial number list give me? “IF” the engine is original to the car, it give me the earliest date the car could have been assembled. And perhaps saying the car was assembled on that date or shortly thereafter – is one way to more accurately reflect when it was assembled.

Good luck with your roadster. You might also want to check the right front floor board riser to see if there is a body assembly number stamped there. Please see the posting “Home for the Holidays” at: http://www.mtfca.com/discus/messages/29/40322.html for additional information on body numbers.

Respectfully submitted,

Hap l9l5 cut off

Thanks Steve and Hap. Good information. I will check the serial number above the water inlet and the postings suggested by Hap.