What heat range of plugs does the Allis Chalmers B need, mine does put out some blue smoke on start up. Would like to go one heat range above factory spects. What is the best brand to use in this tractor.?

Blue smoke is usually oil getting by the valve guides. Guides are probably worn a bit and after the engine sits for a little while, the oil creeps down the guides into the combustion chambers. When the engine fires up, what oil that creeped down into the combustion chambers now goes out the stack as blue smoke. Usually clears up once the engine is running. If its worn oil rings or the rings going away little by little it'll continue to smoke all the time the engine is running. Black smoke would indicate a rich mixture.

Autolite plugs are what most AC guys run. Some have good luck with other brands such as NGK, or AC. Champions seem to be junk although there are a few here that still run em' without any problems. Personally, I wouldn't waste my money putting them in anything. But, that's just me. I would say to use the Autolite 295 plugs. Its a little warmer heat range than the regular Autolite 303's. In Autolite, the last digit of the plug is the heat range. The higher the number, the hotter the plug.  HTH

Steve@B&B