carb backfire problem

[charger01]

I got a few hundred miles on my 69 440 now.  it backfired out the carb once going down the highway, but didnt cause a problem.  then it backfired loudly upon startup this afternoon.  Well I took my wife and son out to eat tonite and about 55 mph it backfired loudly through the carb.  ran ok for 15-20 seconds then smoke started pouring out of the hood.  I opened it up and the air cleaner assembly was engulfed in flames.  I luckily had an extiquisher, but any ideas what would cause this.  Scarey situation for my son.  I dont want it to happen again.  running an edelbrock , and no major damage was done that I know of, but want to get it back up and running soon and correctly.

[resq302]

Could be running lean or rich and dumping raw fuel into the engine.  My dads el camino would do that and cause a fireball to go up like yours did probably.  Id first start with a carb rebuild and then go from there.

[RallyeMike]

Could be several things.... Start with the easy stuff:

1) Checking a plug to see how rich the car is (black / oily / sooty = rich).
2) Verify the timing is correct at 36 degrees total advance at around 2500rpm.