I just broken in my .12 Rossi/Pixie engine. The engine came with .3mm worth of shims in it "out of the box". After checking the piston at TDC and the button depth WITH THE SHIMS INSTALLED my deck head height is 1 mm. I know most .12 size engine running 30% nitro should be around .55mm. I've never had to remove shims to set the engine up to run 30%. Without the shims the deck head height is .63mm. Anyone got any ideas