12YDTAH10766

This number would identify the block, but did they come factory with the big valve heads???

Thanks.

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Santo

"The Lone Ranger"
HI-HO Silver......AWAAAAAY!

They came with a 12G940 head which has an unshouded combustion chamber and relatively large valves and ports as compared to earlier small bore heads such as the 12G202 heads.

So basically, that motor worked to 1310cc with that head should go pretty good???

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Santo

"The Lone Ranger"
HI-HO Silver......AWAAAAAY!

Short answer - yes
Its what I have on my 1310 mini and it goes fine. My motor has a MG metro cam, HIF44 carby, extractors and it will go faster than i want to drive it.

Of course the head can be improved considerably by a good gas flow professional but they were pretty good heads straight out of the factory. They breath well compared to the relatively inefficient heads on earlier small bore motors

The 1100S head is basically the same casting as a Mk2 Cooper S head, except the inlet valves are 1/16" smaller and it has single valve springs not double.
Very easy to fit S inlets, these days it's a common way to make up for worn valve seats.
If exhaust seats are worn, fitting unleaded inserts is a good remedy.

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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.