Olds engine ID

[Dave Severson]

Could anyone help with a link on Oldsmobile engine ID??? On the block, I found the number: 369021 F (not sure it is an f or what it's supposed to be. On the cylinder heads: 411 788. Would like a source to find out what year, what size engine it is. Belongs to a friend of mine, doesn't have the heads off of it yet so I can't tell ya what the bore size is, will check on that next week. Thanks in advance for the help.


I know this has nothing to do with engine tuning and doesn't belong here, but no forum for Oldsmobile engines.

[drg84]

Hey Dave, Its Dave. I think I can help you with that Olds motor. The 3 means its an Oldsmobile block, the 5 means it was built in 75 or 85. the F means its a 260. If you want to confirm this, a 260 oldsmobile has a 3.5I bore and a 3.8I stroke. Remember, All 307s came with 4bbls stock and 260s came with 2bbls. As for 350s, I do believe they came with both. If your friend needs any help with that motor, Feel free as IM me. Later

[Dave Severson]

Thanks, a guy sent me the info:Big Block Identification

* A big block measures 14" between the heads at the manifold base.
* Facing the front of the engine, at the top surface of the timing chain area, to the left of the oil fill tube, there is a code about 1.5" high followed by the casting number. A letter indicates a big block, a number indicates a small block.
* Big blocks have a little hump in that area, whereas the small blocks are flat the whole way across.


ID/ Casting
Code Year(s) CID Number Notes
A '65 425 381917?? 1st year, big cars.
386525
B '65 400 389298 442 only, one year only.
D '66 - '67 425 389244 Big-car engine. Toro is different internally.
E '66 - '67 400 390925 442 engine [VERY rare].
F '68 - '70 455 396021 Common big block. Stick type F (sans serif).
F '70 - '72 455 396021 Common big block. Serif type F. Two vertical
and a base serif.
Fa '72 - '76 455 396021 Very common big block. Marine also (L VIN derivative).
8