I've got a head shim question. My engine came with .3mm worth of shims installed under the plug button. While measuring the piston at TDC and the plug button depth; my head clearance is at 1mm this seems way too much. I plan on running 30% I would actually have to remove the shims to get it close to the recommended head clearance of .55mm for a .12 engine. The best head clearance I can achieve is about .63mm (with no shims installed) I used my digital calipers to make the measurements any one have any Ideas. The engine in question is a Rossi/pixy .12 (gold head)