I"m afraid I know the answer, but I"m going to ask any way. I guess 80psi of compression is not enough 226 engine to fire. I"m at a loss. I drove this tractor into my shop, ran a little weaker than I thought it should. I thought a valve job would help bring back it"s youth. Lapped the valves everything looked great. 1St head gasket and only 30 psi compression. Had the head decked 2nd gasket and now I"m up to 80 psi. Yes valves are set right. Blow down test sounds like the head gasket. I"m just thinking out loud before I break this tractor in half and rebuild this engine. Any one have any thoughts.