The Stovebolt Site Forums The Parking Lot Big Bolts Decoding the numbers on a 261?

Picked up a 261 for my 3100 the other day and I'm trying to figure out exactly what I have.

Date code is K-24-1

Block casting is 3733950

Head casting is 3701887

Stamped ID # is 0018991F


And here's the confusion...
From what I've found, the date code suggests that this engine is from Nov of '61 but the block number lists it as an early 261 from '54. The smaller fittings for by-pass oil filtration and lack of captain's bars on the block would suggest the same.
The head is another topic all together...it's number suggests that it is from the last of the low pressure 235s, yet it has the steam holes or water passages drilled into it.
Unfortunately I have yet to find anything on the number stamped behind the dizzy.

3733950 is a block casting code from 55-57 (and, maybe other years). Where did you find it listed as a 1954 code?

3701887 is a 1953 truck head casting code (as you posted).
The extra coolant holes could have been drilled into the earlier head.
What is the date casting code on the head? It is under the valve cover on rearward driver's side of the head.

As you posted, the engine serial number is not a recognizable format. You might have a engine/block that was re-stamped when used a replacement?

I found the cast block number as a '54-'55 261 on the Inliners site.
Screenshot - https://farm8.staticflickr.com/7550/15782968312_b6c8e2d7f2_c.jpg


It does have an older rebuild tag on it. So the head might be a replacement and the ID might be a re-stamping.

I'll check the date casting code on the head tonight.

Thanks for your input, Tim!

BLUEMEANIE,

Is the water pump entirely below the bottom of the head (55-2nd and later), or does the water pump body extend above the bottom of the head (54/55-1st)?

Ain't this detective work fun?