maybe I've been old schooling it too much. I have been using delco plugs rated one heat range up (correct gap). My thinking being that this will ensure best burn. However, another post got me thinking. Have I just been making things hard for my carb and/or engine by using too hot a spark range? what you think about spark plug heat ranges?

 

The plug temperature has nothing to do with how well it makes the mixture burn, it's how easily the plug conducts heat away from its tip. If the plug is too cold, it will conduct too much heat away so that the tip won't get hot enough to burn off deposits, and the plug will foul. If the plug is too hot, it won't conduct enough heat away, and the plug tip will heat up and become a glow plug causing preignition.