I just bought a 91 RS with a newly built 305 in it and I need some help. The engine will crank up easily but when you go to pull off it will backfire back through the TB and die. IF you can get it to actually pull off it will spit and sputter very bad and cut off. A little back ground on the motor...its the stock 305 block bored 30 over...balanced and blue printed...stock cam specs...double hump heads (the stock intake has been "modified" to fit them )...MSD distributer, wire and coil. I basicaly stole the car but would like to get the engine running right before I pull it out...any ideas where to start? Does it sound like a computer/TBI problem or timing problem? I am thinking an intake and carb might solve the problem...any input would be greatly apprecaited though.

 

with the bcak fire like that sounds like you need to check the timing as
you might be 180* out of time. start at that and check that all the wires are on the correct locations and should fire up and run for you.