1/2 INCH PIPE THREAD. This plug and box are in excellent unused condition. The 1/2 inch pipe thread fits Model T Ford and many other pre 1930 engines. 1/2 inch pipe thread was also used on many hit and miss gas engines. When the item is received, if you are pleased please leave positive feed back and I will do the same, if there is any problem please contact me. To view our other. The item “Champion Priming Spark Plug, Model T Ford, Hit Miss Gas Engine, NOS” is in sale since Sunday, July 28, 2019. This item is in the category “Collectibles\Transportation\Automobilia\Spark Plugs”. The seller is “midojo” and is located in Boone, Iowa. This item can be shipped worldwide.