FIGURE 32-1 A spark tester looks like a regular spark plug with an alligator clip attached to the shell. This tester has a specified gap that requires. - ppt download
The Spark Is Gone: How to Test Your Vehicle's Spark Plugs
Amazon.com: Tool Aid 23970 in-Line Spark Checker Kit for Recessed Plug : Automotive
In-Line Spark Checker Kit for Recessed Plugs | Tool Aid