parkplug well too long for high cylinder ?

[Michael D]

Do you think that it necessary to machine the sparkplug well to reduce by the top the head cylinder

@ Creusois: this indeed looks like a Ricardo head. From correspondence with David Dye (who sells new Ricardo heads) I've learned that there is very little room to modify the head (f.i. by machining) due to the proximity of water passages. When you take a look at the Ricardo patent drawings in Nick Lettingtons' post (#6) it's obviously clear that machining the spark plug hole is tricky to say the least; you might break into the water passages or in the best case scenario have very little alloy left between the spark plug hole and the water passages..  So I'd rather fit a spark plug that's  flush like Reckless Rat has indicated (in post # 10 referring to post #6). Skimming a repro Ricardo head is tricky too. But if in doubt: consult David Dye. PS: the head you have does not resemble the Ricardo head I have as manufactured by David Dye