Great thread, enjoying following the progress, my own workshop is like a butchers shop when I am fabricating bits, looking at the head work, due to the high compression on this A10 I am working on at present, I was thinking of looking at the feasibility of compression releases such as fitted to Harleys, you can have them blow closed on combustion so easy to operate without going too technical,the thread on them is 10 mm so not too big, need a gash head to check out the possibility? Sorry not meaning to hijack this thread, I love to see talented individuals pushing the boundaries with projects like this, fantastic keep up the good work. Dave