USEFUL HINT

NZ Truth, Issue 1062, 1 April 1926, Page 16

USEFUL HINT

CLEANING MICA To Avoid Scratching A correspondent .asks how to clean tlie ,mica insulation which is found on several popular makes of sparking plugs. important thing to remember when doing this is that the mica must on no account be scratched. / If rough emery paper or a pen-knife is used to remove the carbon, the scratches which will be left on the outside of the mica will tend to set up rapid carbon deposit when the. plug is again m action. t It should be possible to remove the carbon with a rag dipped m petrol, after which the mica should, be polished with liquid metal polish. The idea is to obtain. as high a polish on the insulation as -possible. i It will be found that m the. plugs which are used for high speed work the mica ' is ;polished to such a' high degree as to resemble a dark stone rather than the usual rather fluffy appearance which one usually associates with mica. ;■■ ■ i