137 engine is now virtually complete and restored with a new piston, rebuilt clutch ,re cut valve seats, made up an adapter to fit the 12tooth mag timing sprocket and set the ignition timing whilst I had the head off. Starting to look like an engine now instead of a pile of bits. The combination of thread types is a nightmare, UNF,BSF, Whitworth and UNC all on the same engine, I seem to spend hours ratching for the right nut or bolt in my various bins and boxes and failing that have to set to and make them. Just need to machine a set of new head bolts and then basic engine will be finished and sealed before I start on more rubbing down and grinding.