sorry to disagree but what you say IS NOT TRUE. IT MAKES A He**of a difference with some two stroke engines & im speaking from experience over years with a number of engine brands & sizes in positions from vertical to 90 deg to fully inverted to every angle in between. the reason is simple . the head acts as a "sump" to pool fuel regardless of the carb mix, location & settings. it has nothing to do with carb location.IF the engine is very well broken in you might get away with it & even then there will be some hesitation but you cant help but experience some pooling. also in some scale planes you have little choice as to tank location . you MUST use a glow assist. In 90 deg position there is no problem however, using pitts muffler in tight cowl ive noticed considerable changes in settings due to heat soaking.