Alfonso et al,
True enough, you can have everything right on the nose and not get instantaneous fire. But, like everything else in life, there is always an explanation. Sometimes the sheer length of the intake runners, combined with things like the engine's need to turn over enough to establish a vacuumn, or the time it takes the fuel pump to replenish the float bowls to a level whereby the fuel height in the jets is enough for that developing vacuum to act upon, or even the wait while a random droplet or two of fuel atomizes suffficiently (at such a low air velocity) to form the right mixture ratio to fire in a cylinder under pressure at some given cool temperature. Of course, modern fuel injection systems will have none of this inefficiency! They force" the optimal conditions at all times. When a modern fuel injected car doesn't start within ten seconds or so, it's tow time. Don't you love our "old " cars?
Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon