Quick update.
Having taken the core plugs out of one end of the block and poked around with a bent wire I'm not convinced that it would be wise to machine anything useful off the top face. You might get 1/16" but if the core plugs weren't perfectly placed all through the casting it might become dangerously thin. So the vestigial register is all there is.
So I've made the tappet cover from 10mm aluminium plate. It rests on the crankcase at the bottom edge and has an O ring groove in the top, nicely squeezed into place in the gap. The 3 "easy" faces have an O ring groove that sits in same place as the normal gasket.
Charles
Having taken the core plugs out of one end of the block and poked around with a bent wire I'm not convinced that it would be wise to machine anything useful off the top face. You might get 1/16" but if the core plugs weren't perfectly placed all through the casting it might become dangerously thin. So the vestigial register is all there is.
So I've made the tappet cover from 10mm aluminium plate. It rests on the crankcase at the bottom edge and has an O ring groove in the top, nicely squeezed into place in the gap. The 3 "easy" faces have an O ring groove that sits in same place as the normal gasket.
Charles