I came across the problem that the piston of a R68 , belonging to a friend of mine, slightly fouls the spark plug. Doing so, the gap of the plug is almost closed. However, the piston does not touch the head but keeps a reasonable distance. Now two questions arise from this:
How much distance is necessary to safely avoid contact between head and piston at high revs?
Which is the original height of the R68 cylinder? (I imagine to cure some earlier tuning effort using a thicker gasket under the cylinder)
And a last one: Is there something like a R68 register in existence ?
Thanks a lot, best regards, Thomas