pos won't run...pontiac

i have a 77 firebird with a rocket motor in it. I did a tune-up and replaced the carb and it will not start. It will pop out the carb occasionally and catch on fire. i have no clue what is wrong??? also the engine is not original and that is another problem. i think is is a 1980 block so is there anything special i should know about it? please help this thing is starting to tick me off. it has spark just an orange regular spark. The carb is giving gas. The firing order is right and the timing i have messed with alot and not change. Oh yeah it is hei ignition.

by the sounds of things, your timing is off. make sure your firing order is correct, get #1 to TDC, and make sure that your Rotor is pointing at the #1 wire. and go from there. your distributor may be 180 degrees out.