Most EA / EB / ED have the gas mixer on the outlet of the airbox, where the duct to the throttle body goes.
Therefore, when you try start the car, the gas / air mixture is basically from the air box outlet, all the way to the throttlebody.
If you have bad leads, most of the time the spark will jump from one to another where they run parallel with each other over the rocker cover, causing the engine to backfire through the intake, then igniting the gas / air mixture all the way through the inlet tube, and the airbox takes the blast.
It is a very common problem, and most of the time its due to dodgey leads. Rarely due to incorrect timing or coil / tfi problems.
If it were a leaky gas soleniod, you would be sure to smell it after a couple of hours when the car is sitting (overnight?)
On another note, most E-series falcs on gas do not have the induction snorkle on them, this is for two reasons - one is to prevent engine stall when slowing down coming to a set of lights etc, and also to stop the airbox self destructing in the case of a backfire.
Last edited by 9psi EB; 07-12-03 at 02:12 AM.