I am helping an elderly gentleman with his 1949 C that is hard to start. About 6 years ago we put new rings in, honed it and rebuilt the head. It has a Marvin Schebler carb on it. It will fire once and then the white vapor comes out the pipe which I am assuming is raw gas. He put new plugs in (Champion, J8C, ugh) and it fired and ran great the first couple times and then it gets hard to start until he cleans the plugs again. I asked him to get the Autolite 295 but he said they were unavailable. Does it need a hotter plug? he only runs it 20 minutes to a half hour each time. He hasn't been using the choke since he had someone "adjust" the carb. It was hard starting before and after the carb adjust. the metal base of the plug looks stained but not black and the porcelain looks like the coffee/cream color. He can pull start it instantly in 3rd gear with another vehicle but it doesn't want to start on the starter. It has a magneto. Any help would be greatly appreciated.