Getting a little frustrated, need some advice on what I am missing. My 8N for the last 15 years has always started immediately. It sets for periods of time up to 6 months, but that never affected it. This last resting period it will not start and only back fires occasionally. I assumed it was electrical and replaced plugs, wires, coil, points, condenser, dist. cap and rotor, with the same results. Got compression stroke using finger over #1 cylinder, set timing at 4deg. BTDC and set point opening with OHMs meter. Left distributor just loose enough I could make slight turns while trying to start, still the occasional backfire is all I get. I converted this tractor to 12 volt 15 years ago. Since it was running when it was parked I have to assume nothing with the timing chain could have changed which leads me to fuel. Has anyone else experienced this type of problem simply from the carburetor? Also this is brand new fuel.