my boy said he heard screeching comeing from the block when he turned the motor over and he thinks its locking up cause i put that copper exhaust sealer sshit on the head and block to seal it and he thinks when i torqued down the head it smashed that copper shit into the way of one of my oil squirters or something scratching my cylinder wall??? does that sound right??? the motor makes a thud noise when i turn the key over and when i turn the crank by hand at one point during the rotation it gets hard as FUCK to turn the motor over , maybe bending valves??? i have a set of gsr valves ,springs and retainers waiting to be put on just in case i bent some valves but i dont know what to do im going by what my boy said how hard would it be to change valves??? i need help on what i should do thansk guys, john