Mine lights off instantly... I think the new fuel boils off due to engine heat.. In a modern fuel injected car where the fuel is injected & the fuel is always pressurized it's a non-issue but a carburator where the fuel sits on a hot engine....I've blocked the crossover & added a heat shield...

http://images.google.com/imgres?imgurl=h...sa%3DN%26um%3D1