i got my motor together a few days ago 727 big bore 12;1 comp. stage 3 hot cams . got oil presure up on it started it got a noise like a nocking. i think i got a valve touching the piston. anyway my question is when i take the head off will i have to get a new head gasket ? The motor has only ran a few minutes on the one i just put on. or is it still good. thank you