Classic/Antique Car Repair: 1972 chevelle, exhaust stroke, compression stroke

Question
hi im having problems getting my chevelle to start i put a 84 350 small block in it completly rebuit with some upgrades i put a brand new holley 4 barrel carb on and it only wants to backfire not start. the timing is definitly correct i am sure of that any info you have would be great thanks

Answer
I'll be willing to bet at least twenty five cents that the distributor is off by 180 degrees. The distributor can go in two ways and look like it is timed perfectly. Remember that the crankshaft turns twice as fast and twice as many revolutions as the distributor. That is because it takes two turns of the crank to make four strokes of the piston. You probably have the distributor in so that the cylinders are firing at the end of the exhaust stroke and the begriming of the intake instead of at the top of the compression stroke.
Brad