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Hi Michael,Thanks!If you look back through the build log you will find a long list of the mistakes I had to correct before Mastiff would run well. These included leaking gaskets, over-size main jets, wrong timing and leaking home-made spark plugs. The compression ratio is about 3.8:1 and at first there wasn't much compression but this has developed as the engine has been run. With small cylinder volumes the thickness of the head gasket has quite an effect on the CR, could you try a thick gasket to reduce the CR?
Jim,The short answer is that Len Mason provided a diagram of the angular positions in his book on "Building Mastiff" and I followed this very carefully:The original diagram was about 2" by 2 1/2" and the reproduction not very good so I scanned it and printed it A4. The generally poor to very poor reproduction of the drawings in the book was one of the reasons I re-drew the whole engine in Geomagic Design. Having the 3D CAD meant I could produce my own drawings and pictures as checks (.pdf s attached). Moving each cam to the correct angle in turn required the dividing head to be turned backwards or forwards by various angles and I worked out these angles and wrote a list of the moves needed. The last picture in the post looks enough like Fig 15 on p87 of the book to be reassuring.The essential design info needed to work out the angles for yourself is that the camshaft turns anticlockwise looked at from the timing end, on each cylinder the cam nose centrelines are 110 degrees apart with the exhaust leading. The firing order is 1,2,4,3.Thanks for the interest!Dt