its physics louie the piston would hit the head , you only have a couple thousandths piston to deck clearance on any b series motor definetly not 3mm's plus which you would need to get an extra 6mm of stroke ha ha ha ha a stock ls has 0.013 piston to deck height and a stock oem 3 layer head gasket is 0.026 so u tell me how u got your piston to go up 3mm on the upstroke of and not hit the head??? just an fyi louie not flaming