When I said that my latest casting was almost perfect I meant it relative to the previous one! What I should have said was that it is usable and it shouldn't be necessary to do another.
Getting the core sand out is a problem, I've soaked it and attacked it with a kitchen fork and finally had to resort to an electric drill with a masonry bit. I still haven't got it all out but I needed a rest from it.
Well here it is, as I mentioned before it will need a cover plate made for the area where the camshaft will be,(at least I will be able to see what the cams are doing as I assemble it). It will also need some filler for the rough areas of the casting.
Some parts of the pattern had no draught built into it, I had hoped that when I rapped it I could loosen it enough to allow removal from the mould. That was not the case and as a consequence quite a lot of the edges of the sand broke away resulting in very large flashing around the joint area. Lesson learnt, time spent getting the pattern right will pay off.
My angle grinder burnt out a few months ago so I now have the choice of a lot of filing and sawing or to spend some money and buy another grinder. Roll on car boot season!