3769925. Captains bars above the starter, with two other numbers CON3 L174 above the starter too. I thought there was always a number stamped on the Distributor flat, but this one doesn't have any numbers there . . .
. . .
I had them clean, magnaflux, bore to .040 over, do the normal prep, turn the crank, etc and then sell me the new pistons, cam, rings, etc, etc. and I did everything myself. So, really wish I had known! Now that its on the frame, tuned and adjusted, bad time to find it.
That block casting code is, as you indicated, a 1958-63 code.
If it is a 1958 or later 261, with a L174 date casting code, it looks like the block was cast in December 1964. If that is correct, it would be a replacement block. That would explain no Engine Serial Number.
Did your engine shop tell you from whom they obtained the block?
Do you have an oil filter on that engine? If so, is it a by-pass or a full-flow; and, into which holes in the block is it plumbed (a photo of the plumbing/line-attachments would be interesting to see)?
Have you attached an oil pressure gauge to the engine while it is running (or, have you not run/broken-in the engine)? If you have run the engine and attached a gauge, where did you attach the sender line and what was the pressure reading?
