NEVER try to start a glow engine upside down, the chance of a hydralic lock bending or breaking a rod is very high. You can still flood the engine right side up too. The very best position for starting is with the engine on its' side and the exhaust port facing down. It is easier to draw fuel into the chamber and to dump excess fuel out the exhaust if there is a flood. C/L combat guys get one flip starts 90% of the time this way.