I took the MGB out for a spin today. She starts right up and runs good. Still smoky, but better, I think. I added more magic potion to the offending cylinder when I shut down.
I found some Bosch Platinum+2 plugs on clearance at Walmart, Squeezed the electrodes as close to the center as they would go (about .035).
Here is their propaganda:
More platinum in the center electrode with two yttrium-enhanced ground electrodes and a more powerful spark.
If you require smoother acceleration, better gas mileage, and optimum engine performance, Platinum+2 is the spark plug for you. Unlike conventional air gap spark plugs, Platinum+2 uses surface air gap technology. The spark of a Platinum+2 first travels over the surface of the insulator nose and then arcs across the air gap to a ground electrode for a longer spark, without increasing the voltage requirement. Plus, the yttrium alloy ground electrodes help to reduce gap wear and oxidation, extending the service life of the spark plug.
Only Bosch offers this revolutionary firing technology, which combines the advantages of platinum, multiple electrodes and surface air gap technology for optimum engine performance.