My Chain recently snapped, Tensioner gave up, ive just finished rebuilding the head and new Timing chain kit. Car is running fine, but noiced when i was cleaning the top of the block for new gasket to be fitted. Noiced that when i was cleaning the top of the pistons, i could rock them backwards and forwards, only about half a 'cm' is this normal or are my piston rings on there way out???? i have a little bit of smoke from the exhaust when accelerating (only puffs out about 4000rpm). Any ideas?