My friend swapped motors (blown head gasket), and now the motor he bought doesn't want to fire. It has fuel, spark, and the distributor was dropped at TDC, but still it doesn't want to turn over. The motor was rebuilt 30k ago, and had no previous problems. The firing order is correct, and the brown/black wire was disconnected to set the timing. Is there something that he's missing? I've been racking my brain over this the past week. Any suggestions? Thanks.