CEV,

How much your widebody weighs? I am using a 91 FX on my K-trick 90 which weighs about 3600 grams. With straight 80/20 non nitro fuel I hand launch it vertically 90 degrees and it goes vertically unlimited.I am using APC 14x6, coz I prefer low pitch for better vertical. no problem with the carb.

Are your fuel lines too long or there are multiple bends of fuel line which can cause head loss of pressure? check your fuel tank also.