ONE OF THE OLD TRICKS WITH MY INVERTED OS 77 DUCTED FAN ENGINES WAS A OS #8 PLUG AND USE A SMALL PICK OR STIFF WIRE AND BEND THE TOP COIL JUST A SMALL AMOUNT UP SO THAT THE COIL WIRE IS STICKING UP PAST THE BODY OF THE GLOW PLUG. THIS KEEPS THE COIL GLOWING BETTER WITH THE COLD AIR FUEL CHARGE COMING INTO THE ENGINE. REMEMBER THAT WHEN THE METHANOL AND AIR MIX AT THE CARB IT GETS REALLY COLD TO THE POINT OF ICE FORMING ON OUTSIDE OF THE CARB. SO RUNNING IN COLD WEATHER AMPLIFIES THE PROBLEM. ANOTHER LITTLE TRICK MY CHEMIST BUDDY CAME UP WITH WAS 1/2 OZ. OF AC PUMP OIL TO ONE GALLON NITRO FUEL,,,, WHEN THE AC OIL BURNS IT PRODUCES OXYGEN AND WE ALL KNOW THAT FIRE IS NOT FIRE WITHOUT OXY. WE USED TO RUN THE JETS IN COLD WEATHER AND GETTING THEM STARTED WAS HARD. POPING GLOW PLUGS SOUNDS LIKE LOTS OF FUEL WITH NO GLOW IF THE COIL IS NOT BURNED AND CRUNCHED UP INTO BODY OF GLOW PLUG, OR IF THE COIL IS BURNED OFF THEN SHES GLOWIN BUT TO LEAN ON THE FUEL.