Crank pulleys will not bolt to balancer

To find TDC, best to mark where you have a certain piston drop on a dial indicator (say 50 mil), on both sides, then mark TDC halfway between the two. At TDC, the relation between crank angle and rise goes away, i.e. angular sensitivity => 0. You could rotate the crank ~2 deg around TDC and not notice the piston move.