Re: Sandblasting spark plugs???
I have used a plug sand blaster (Harbor Freight), they do clean the plug, but remove the Cad plate off the metal and threads. You have to clean the threads when your done, and blow the plug out with compressed air to clear it of abrasive media. Any media in the threads will mess up the threads in the spark plug hole, so be careful. Due to the Cad plate being gone, put some anti-seize on the threads of the plug.
I once saw an SAE study done on the resistivity, and insulting properties of spark plugs that were new, used, and cleaned by several processes. The wire brush method had the poorest results due to metal being deposited from the brush on the ceramic insulator. Cleaning with solvent and bristle brush was a little better, and media blasting was a little better yet. Interestingly however, none of the cleaned plugs were very good compared with a new plug as far as insulative resistance. Amazingly, a used plug from a good running engine that was not fouled was better than a cleaned plug's insulative properties! They determined that the porous ceramic absorbed carbon when cleaned with solvents and degraded it's insulative properties. Media blasting removes the finish of the porcelean surface of the ceramic insulator, making it rougher and easier for solvents and carbon to penetrate.
This paper was probably written by an engineer working for Champion, as the obviouse point is that nothing beats a new spark plug when it comes to getting the best spark, and performance.
I have found that with a plug that is new, but fouled black due to a rich condition, if I just blow it dry, and correct the mixture problem, then run the plug in the engine under normal load for a while, it burns clean and takes on a nice light tan color.
I run my plugs until a light deposit begins to form on the insulator, or the center electrode just starts to erode. You save old used plugs that are no longer made, and blast them, but I always use new plugs if they are availlable, as they are only $2.79 each.
