Small Block & Big Block Chevy Specific - starting problems

Hey i got a sbc with a lt1 intake with megasquirt system on it. When I try to start it, it backfires inside the intake. I was thinking maybe the timing is off but im not sure why its doing this. Any suggestions??

Isnt the LT1 intake different,if not is it leaking between the intake and head mating suface.

yes it is different actually. But it can be modified to fit. i wasnt sure if it could be a vacuum leak or the timing. i will try nd check the manifold to see if it may be leaking. Since its igniting into the manifold would it more likely be the timing?? i appreciate any help thanks

i figured it out, i dont want to even tell you what it was but i will lol...i somehow managed to put the distributor facing the exact opposite direction of the first piston at TDC. I made the proper adjustments, now its running pristine...Thanks for your help tho.