Quote:
Originally Posted by daren007
Sand blasting spark plugs? Bead blast yes but sand?
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Yep, sandblasting! From at least the '40's through the 60's just about every dealer and independent shop had a spark plug cleaning machine that used sand and compressed air to clean carbon deposits off plugs. Most were sold by AC (the spark plug company). First you put the plug into a rubber grommet on top of the unit and hit the blast valve, which blasted the plug electrodes with sand using shop air. Then you hit another valve to blow the grit off the plug. Next you threaded the plug into the test chamber and attached a high voltage lead to the plug terminal and turned on the high voltage, which sent a steady arc across the plug. There was a mirror so you could see the arc going across the plug gap. Then you added compressed air to the chamber and watched to see at what pressure the spark was blown out or started going down the center insulator instead of jumping the gap. I forget what the minimum pressure requirement was for the plug to pass but if it didn't pass after cleaning and re-gapping, it was time for new plugs. Yes, "clean and re-gap spark plugs" was a standard tune-up procedure.