I have a 49 or 50 John Deere B. Not sure exactly what year because the serial number tag has been missing for over forty years. I run only Shell Premium fuel and lately it’s been very hard to start. Once it starts, usually after a backfire or I pull it to start it runs perfect. I have a good strong 12 volt battery, spins like a top but just don’t want to start. I took the plugs out and wire wheeled them, set the plugs at .030 and it starts kind of ok for a few times and then the same problems. My dad had this tractor engine rebuild 45 years ago and it is always ran great. Just frustrating the hell out of me the last couple summers.
Any thoughts?