Got a hpi t-15 off ebay needing a head dident think as got a new head with my parts only thing is dont know what its off fits ok needs shim so have orderd 1 does any one know if it ru or the gap beetween the head and piston any help would be good as my rc shop about as good as a chocolet tea pot

Got a nitro t-15 hpi the head button gone.:mad got spare head fits ok have no shims so orderd one but the top ov the slev and the engine were the head seats thars a 1-2ml gap the head i got has half a ml drop in the engine when it sits ready to be bolted on when the shim comes hope its thik anoth. Does any one done this before???as this is new to me dont know if it will work hope so.???????????????