Engine serial number question

34fordy

34fordy

Well-known member
On VanPelts site it states that Ford switched to 24 stud engines beginning with 18-4,380,120.
My 21 stud engine number is 18-4,645-xxx. Wondering if there is an explanation for this. Thanx
 
>>>>My 21 stud engine number is 18-4,645-xxx.>>>>


I think that's the transmission number. So probably means you got a newer transmission attached to your 21-studder. Congratulations.
 
The engine did not have a number so that they could be swapped out when a rebuild was necessary . Transmission was numbered.
 
Jack E/NJ said:
>>>>My 21 stud engine number is 18-4,645-xxx.>>>>


I think that's the transmission number. So probably means you got a newer transmission attached to your 21-studder. Congratulations.
Click to expand...

I knew that at one time but "brain freeze" set in! The engine has water pump block-off plates with early heads. It must be 37 or early 38. It would be nice if the box was a 39.
 
The change to the pumps in the block started for the 1937 model year production but the block only lasted approximately 2 more years till the change over of the 221 blocks to 24 stud configuration and the new 24 stud 239 blocks for the 1939 Mercury debut.

The last of the 21 stud engines were good engines but Ford was looking to get better bolts spread on the blocks so that they could get better cylinder head sealing and a bit more room for boring the cylinders. Ford was experimenting with the tin can sleeves in the 1939 thru 41 time frame.
 
I have a very orig '33 3w with its '33 flathead. BUT a 39 trans without a number on the trans bell housing. (The floor shift is '39/'40; the '33'34 had a straight stick.)

Odd; don't you think?
 
In 1952 say, it would be a lot more common to find a '39 transmission in a junkyard than a '33. Since it will fit, nobody worried about originality or serial numbers in those days.
 
Or the transmission case was a service part, which of course came without engine numbers stamped on them.
 
Ford used that case up into 1952 for light duty pickups (F1). They were no longer stamping the transmission case with a VIN after 1947 for the F1s and after 1948 for Ford cars.
 
Gary Mallast wrote a good explanation of the 21 stud to 24 stud change over in the 38-39 book. I'll try to paraphrase here.
Ford built 21 stud motors before 11-24-37.
Ford built both 21 and 24 stud motors from 11-24-37 to 12-7-37 for new vehicle production.
Ford built 24 stud motors for new vehicle production after 12-7-37.
Ford continued building 21 stud motors for service replacement use through 10-4-38.


Be aware that engine build date and car manufacturing date were frequently months apart. Engines were in transit to and in storage at assembly plants before they were installed on the line. The assembly plants made no effort to install engines in numerical order, that is there was no effort to make sure a serial number was later than the one of the car ahead on the assembly line.
 
Be aware that engine build date and car manufacturing date were frequently months apart. Engines were in transit to and in storage at assembly plants before they were installed on the line. The assembly plants made no effort to install engines in numerical order, that is there was no effort to make sure a serial number was later than the one of the car ahead on the assembly line.[/QUOTE]

Was the frame stamped to match the transmission number or was it vice versa?
Also, was the transmission attached to the engine when it was installed in the frame?
 
I will update this post when I find the reference material.

Per my memory: the frame was stamped to match the transmission. Engines were made in the Rouge plant for USA production. Transmissions were mated with engines, then a serial number stamped into the transmission. The engine/transmission assembly was then either sent to the assembly line at the Rouge or was shipped to another assembly plant for use. Once the engine/transmission assembly was dropped into the frame the serial number was stamped into the frame.

Edit: David Rehor describes the process above in the 1932 Ford Book. I'm 99% confident I remember reading in another reliable source (I think in The Early Ford V8 as Henry Built It by Francis / DeAngelis) that this was the practice at least through the pre-war era.

Second edit: I went and looked at the 1940 Ford Book by Mike Kubarth and it also describes transferring the serial number from the transmission to the frame at engine/transmission installation time.

Hopefully David Rehor, Mike Kubarth, or another very knowledgeable individual will drop in on this thread and add details or correct my mistakes.
 
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38 coupe,


You have it down pat. The transmissions were attached to the engines at the engine plant in Dearborn then serialized with a stamped number while still in the engine plant. They were subsequently shipped as an assembly to the various assembly plants in the U.S. and abroad to those countries whose plants were served by Ford U.S.. The vehicle chassis frames had no stamped numbers until mated with an engine/transmission assembly on the line.
 
34fordy said:
Be aware that engine build date and car manufacturing date were frequently months apart. Engines were in transit to and in storage at assembly plants before they were installed on the line. The assembly plants made no effort to install engines in numerical order, that is there was no effort to make sure a serial number was later than the one of the car ahead on the assembly line.
Click to expand...
Was the frame stamped to match the transmission number or was it vice versa?
Also, was the transmission attached to the engine when it was installed in the frame?[/QUOTE]


Sequential serial numbers were assigned at the Rouge. As the serial numbers were to be on transmissions rather than on engines, there may have been an engine serial number tag that originated with the engine, the stamping of that number being transferred to the transmission bell, after which those assemblies passed through the run-in and testing process. Failed assemblies were pulled and reworked, to be retested again after rework, thereafter to be out of sinc with similarly serial numbered units. Empty boxcars were filled with assemblies as they became ready to ship, thence to be shunted to a siding awaiting transport, or immediately attaching to a train to assembly plants throughout the nation. Once at final destination, assemblies may have been unloaded as needed directly from the boxcars, or would be staged at holding areas near the assembly line. Build sheets determined the synchronous delivery to the assembly line of engine type and rolling frame, and at this time, the serial number of the engine assembly was stamped at three locations on the frame.
 
Thr model A engines were the last to be serialized on the block. The B engines were the first to have the serialization on the flywheel housing. From there it went to the transmission case, which was likely due to the new V8 engines.
 
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