I have a 1098 in one of my engine bays and it has an odd number on it. it starts with 10 but it end with B which is also on the build plate , so I am tipping is factory.

My guess is that it's a factory replacement after the first engine died before leaving.

Thoughts ?

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120bhp with 450kg just fun waiting to happen

We were prob. drunk when we set it up last and thought this will be a good idea

I know that an S means the block was sleeved when new. But I have never worked out the B. I assume bearings or maybe bore.

My Morris 1100 finishes with a B and I have seen other motors in Minis with the same B on the end. It is on the ID plate so it can only be a factory thing.

A bit late but I have found the answer. The "B" on the end of the engine number refers to the gearbox, specifically who and where the gears were made.
The B stands for Borg Warner and these gears were made in Australia by them.

Woo hoo I finally nutted it out (with the help of some technical bulletins from Winabby)

My Cooper S block has a S stamped on the back of the Block. Any ideas?

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I wrote this earlier..

But that applies to the engine number. Where is the S stamped on yours?

From memmory bottom left hand coner on the rear on the lip where it bolts to the Gearbox

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