In the Haynes Manual it shows that you can make a valve cover tool by breaking out the porcelain and removing the porcelain and electrodes out of old spark plugs and then inserting some all thread rod in the metal spark plug shell. I am struggling trying to figure out a way to remove the porcelain and electrode from inside the metal spark plug shell. The electrode is some type of metal that does not drill well and the porcelain does not chip or break easily inside the metal shell. Has anyone done this or have any suggestions? I tried heating it up and throwing in tub of cool water to shock it and no luck, also tried beating on electrode in a vice with a punch and no luck.