Running Lean?

[Teacher John]

My '37 started popping every now and then as I roll down the road. When I shut the rig down, sometimes she'll make a big POP with a wee bit of fire under the truck. Figure I'm running lean somehow. Did the ol' carb cleaner check around the carb. The only point of concern was a small point on the top gasket of the one barrel Carter carb. I changed out the hose from the dizzy to the carb. I need to change the gasket on the Carter glass-bowl filter and fix the wee leak where the fuel line enters the tank. All the plugs are showing lean too. There is a lot of bubblige taking place in the glass filter bowl, but it's not boiling. Ideas?