M20B25 Engine number?

[Grrrmachine]

I just got my hands on a 2.5 M20 from an E34. The head checks out, it's got an 885 casting number and "2.5 2.7" stamped between the spark plugs, but I can't find the engine number on the block itself.

I know I'm looking for a machined flat, but all I've found is this:



But that's definitely got no number on it; I've scuffed it with wire wool and can't see anything. Have I got to strip all the accessories off to find it?

[Speedtouch]

That's the usual machined flat where they are stamped. Try Jenolite rust remover or similar acid and a wire brush.

[Grrrmachine]

I'll get the wire brush on the angle grinder and give it a proper scrubbing then

[Speedtouch]

Careful - you may remove the numbers altogether if they're lightly engraved, as many are.

[Grrrmachine]

Brass brush then

EDIT: Job done. I see what you mean about "lightly stamped". But just what I needed: 256K1