I just bought an 1100S engine for my mini. obviously it is a 1275, but i dont know what parts were used for the internals as standard. The engine has no chest covers (solid side walls) so its basically a cooper S block. i just need to know some info. if anyone knows anything about this engine it would be great if you could share your wisdome with me. bore? stroke? journal size? crank? rods? head? Any info is great

If no side covers, it's NOT a Cooper S block but an 1100S (common 1275 motor) as you said.
Tell us the engine # and we'll have more specific info re crank & rods.

Bore 71.6mm
Stroke 81.33mm
Mains 2.0"
Big ends either 1.625" (early) or 1.750" (late).
Early motors used Cooper S/MG Midget rods, later ones used the 1300 style with big balance weights on the caps.
Head has 1.3" inlets, 1.156" exhausts.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

The reason i say its basically a cooper s block is because thats what i have been told from the president of the victorian mini club. The engine number is 12yd ta h1333,

No its not a Cooper S motor -
My literature says its a motor out of a 1275 Clubman LS with 12" wheels

Its still a good motor and will perform well with a RE13 cam and better breathing. Its a good buy but not a Cooper S motor.

These often get referred to as a cooper s motor as they were the same capacity , a genuine cooper S motor will have the rear cam follower plates on the block under the exhaust manifold and (I think all) had 11 head studs instead of 9 that normal mini blocks had and an engine number prefix starting with a 9 (forget the rest of the numbers off the top of my head , gave up scrounging wrecking yards for genuine S motors years ago , now look for anything 1275 regardless of type) . The 1100S block that was fitted to 1275LS's and many other mini's are a tad stronger and less likely to flex under extreme performance modifications .

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Your literature is wrong! (is it the Mini Kingdom catalogue?) The 1275LS has the prefix 12H902UH.

Engine number 12yd ta h1333 is out of a Morris 1100S. It is a very early one (333rd one) and would have the small journal crank.

I think what the president of the vic mini club meant is that it is the equivalent of a cooper S block.

Anyway 1100S blocks are the next best thing

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Lillee - 1969 Morris Mini K

Yes it was the Mini car clinic catalogue -

Was just trying to be helpful

Nothing wrong with small journal cranks and S rods, lots of these are used in Nb racing.
Tend to crack less than big J ones, according to a certain well-known engine builder.

As M1100 said, Morris 1100S motor. I got one the same too... not much later.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.