Vtg Antique “P-H” Dome Top Spark Plug. Hit Miss Gas Engine Tractor Boat Motor. Here is a nice old unusual Spark Plug for your collection. I have included many photos to show its excellent NOS condition. This spark plug is unual looking from top to bottom. It will look great in any collection or an unusual engine. The thread size is 7/8 inch. Please call if you need additional information. Package will be insured upon request. Most items are packaged with new bubble wrap and new packing peanuts. Sometimes prices are inflated due to the weight of the item. I require all international packages to be insured. Be sure to check out my other auctions and store PLUDGEWORKS. _gsrx_vers_586 GS 6.8 (586). Add a map to your own listings. The item “Vtg Antique P-H Dome Top Spark Plug Hit Miss Gas Engine Tractor Boat Motor” is in sale since Monday, April 25, 2016. This item is in the category “Collectibles\Transportation\Automobilia\Spark Plugs”. The seller is “pludge” and is located in Carleton, Michigan. This item can be shipped to United States.