OLDS 330 or 425

Hi guys.... Recently took the motor out of my 77 442 and here is what I've found so far. Block Id in front above water pump 381917 with a large 1 after it. after taking the tranny apart i see a F5 on the back. Also on the head in the back driver side is W123605

I dont think its either of those if its the original motor. Its either a 260 or a 350.

Hi ant, also there is a 3 on the heads. What would make it a 260 or 350

Heres some data I found....

Small Block Identification

A small block measures 12" 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 have a completely flat shelf.
Small blocks from 1977 onward will have the CID or liters cast in large numbers right above the center core plug. The engine VIN number will also be cast onto the side of the block.


ID/ Casting
Code Year(s) CID Number Notes
1 '64-'66 330 381917 45° cam bank angle.
1A 330 381917 45° cam bank angle.
2 '68-'76 350 381917
2 '68-'70 350 395558
3 '66-'67 330 394417 39° cam bank angle.
4
5 '73,'74 350 395558
2A '75-'81 260 Solid main webs for 2A's only? At least for '76.
2B ??-'81 260 557751 Windowed main webs. Windowed main webs for 2B's only?
3A '79 350
3B '77-'80 350 557752
4A '77 403 557265 Solid main webs possibly
553990 for these three
554990 casting numbers.
4B '77-'79 403 557265 Windowed main webs always.
?? '85 307 556607
5A '81- 307 3161
D3 350 7582 Diesel

From the outside they don't look different at all because the 260, 307, 330, 350, and 403 are all the same basic block. But externally the distributor, valve covers, water pump, front cover, oil pan, carb, etc are the same.

Some blocks, before 1977, have their ID cast above the right hand center freeze plug, eg. D for 425, F for 455. Olds didn't cast the displacement into the side of the blocks until they went to the light weight design in 1977. The 1977 and newer blocks will have the cubic inches cast in large raised numbers right above the right hand center freeze plug, eg. 403. The 307 will be in liters (5L), and a diesel engine will have the letters "DX" on it. The engine VIN letter will also be cast into the side of the block. Note that the 260 blocks sometimes have the last 3 digits of the casting number cast there, "355", which is rather misleading.

Thanks Mr. Chuck

It's a 1966 330 going off of the casting numbers & the head ID. Since it has a 45* bank angle instead of a typical Olds 39* angle, you might end up having to have a custom cam ground. Typical Olds cam won't work. Also it will have a forged steel crankshaft.

WOW THE DUDE IS BACK WELCOME BACK SIR WOW Missed ya Buddy how ya Been details details

Yup, looks like a 66 330. Whats wrong with it ? If it needs to be rebuilt, do yourself a favor and find a 68-76 350. You can use the heads off the 330. You really don't need that steel 330 crank unless you plan to build a real stout small block. Otherwise you can sell that with the balancer and flywheel to make you some money back.

On a side note, it's not really that hard to find a 45 degree cam.

I'm not sure what's wrong with it. It gets fire turns over but won't crank. When the distributor is moved there is no noticeable change so I went and bought a new haven't installed it yet. Was told motor has very good compression

Make sure your wires to the dist correspond w/ the firing order and are on the correct cylinder/plug.