Howdy! Sorry to hear about your problem with your AC. Make sure that you are getting spark to both the cylinders and at the right time. Double check to make sure that you have the wires on correctly. One other possibility in addition to the ones listed above does exist. I saw it happen on an N series ford one time. It had 2 dead cylinders right next to each other, numbers 2 and 3 if I remember right. When we tore it down, the head gasket had blown between those 2 cylinders. It had not gotten into the water jacket, or cooling system, just ended up with no compression because the air/fuel mix was pumped into the neighboring cylinder. Might give that some thought as well. Best of luck. steve