Spark plug gauge with gap adjuster

A tool for gauging and adjusting an electrode gap of a spark plug, the spark plug having a center electrode and a side electrode, the side electrode having a free end and a mounted end, with a bend between the two ends. The tool includes an elongated scale portion of substantially constant thickness, having scale indicia on at least one side thereof and an inclined gauge portion extending along at least one side of the scale portion which has a progressively increasing thickness beginning near one end with the thickness of the inclined portion being indicated by the indicia on the scale portion. There is further provided an opening in the tool, which opening has a ledge at one side thereof which partially closes the opening, the opening and ledge being sized and positioned so that the ledge fits in the electrode gap, and the side of the opening opposite the ledge contacts the electrode adjacent to the bend, so that adjustment of the electrode gap is achieved upon application of pressure to the tool to alter the degree of the bend.