Table of Contents
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REF: Tools - 129
Spark Plug Tools
To Gap the Spark Plugs
Spark Plug Hole Adapters for Diagnostic Testing
These are used in place of the spark plug to hook up diagnostic tools (compression tester, leak-down tester etc.).
They can also be used to adapt a 14mm TDC whistle or piston stop to a Sporty engine.
This is a homemade adapter (1/4” NPT to 12mm) that's relatively simple to make if you are having trouble finding the adapter you need.
A used spark plug is already threaded for the plug hole. You can grind the electrode off and remove the insulator. Then thread the internal hole for the threads you'll be needing from you hose / apparatus 3) |
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You'll need to tap threads into the gutted out portion of the plug. In order to get good threads in the plug body you need a bottoming tap (no taper).
Or, you will have to grind down a 1/4“ NPT tapered tap and make it shorter until it is able to go deep enough into the plug body to cut threads in the sides.
Break the porcelain off with a hammer (eye protection required). Take a small screwdriver and break up the porcelain under the crimp (portion that holds the porcelain in the plug body ), this will let you grind the crimp only and the job will go faster as the porcelain is harder to grind. Then pull the rest of it out. You now have to tap threads in the gutted area for 1/4” NPT (national pipe thread)in the plug body and you are ready to go. 4) |
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Homemade 1/4“ NPT to 12mm Spark Plug Hole Adapter |
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1)
Deep Diver of the XLFORUM http://xlforum.net/forums/showthread.php?t=395586&page=5
2)
photo by Deep Diver of the XLFORUM http://xlforum.net/forums/showthread.php?t=395586&page=5