put a feeler gauge down the side of the piston between the piston and block when the piston is around 10 mm from tdc this will tell you if it is out of tolerance. haynes manuals have the figures.
could try reassembling without the head gasket and only turn over by hand, this way if it is valve slightly contacting the reduction in clearance will probably be felt or lock the engine.
i have seen similar symptoms on a land rover engine but the knocking was a lot louder turned out it was a botched rebuild and all the big ends were only finger tight so it was only at engine running speeds and therefore loads that the pistons would contact the valves. unfortunately in the mini this means engine out and separation from the gearbox to investigate.
the turbo head gasket is meant to be 1 cc thicker than the copper gaskets when compressed.
on minimania they have one thats 3.4 cc compressed, i think thats the largest they sell.
http://www.minimania...--Mini-Cooper-S
you think that could possibly work?
