Spark Plug Adaptor, with plug, for Gravely 5-hp & 6.6-hp L-series tractors.
Adapts old-style 7/8-18" thread to modern 14mm thread. 
Allows you to use a modern, less expensive plug (available from us) and also use a modern compression checker on your 5 & 6.6-hp engine. 
Special spark plug has long threads, which places ignition point at the same place inside the cylinder as the larger, more expensive plugs. 
Same heat range as Champion W14.