Got the rubber plugs from Mcmaster carr
http://www.mcmaster.com/#expansion-test-plugs/=jng2lsHole saw a metal or plastic plug at least 1/2" thick (my LT500 was 46mm or 1.812" 1- 13/16)")
Drill and tap Pipe Size 1/8", NPTF use a 1/8" fitting



Spark Plug Seals The Head
