The tractor had not been run in 5 months and during the start attempt it fired up for 3 seconds and quit. After that it only turns over. Replaced the points, condensor and plugs, later the coil. Spark tester shows fire at each plug. Static timed the engine to 7BTC. Each cylinder appears to have compression when turned over with the plug removed port covered with my hand, I have not put gauge on them. The plugs I removed where wet, I drained the carb bowl and flushed with fresh fuel.Tried some starter fluid in the intake, even some WD40 in each cylinder. The only result has been an occasional popping from the carb intake. Oil pressure while cranking is about 15PSI. At this point I'm out of good ideas, this machine has been very dependable for the past 20 years.