OCR Text |
Show The shell of an old spark plug in conjunction with a tire gaum, makes a very handy compression tester. The porcelain of the plug Is removed and a washer Is fitted ;it the bottom. The gauge Is next Inserted and tho packing pack-ing Is tamped In and around It. The nut forces the packing down around the base of tho gauge until a perfect--y tight Joint Is made. This instrument instru-ment Is screwed into (he spark plug hole and when the engine is turned over by hand the compression 1" registered reg-istered In pounds. |