I just swapped over a b16a3 with a b16a and now I have no spark. I used the same intake manifold, distributor and wiring harness.

I have no clue where to look first...

 

look at the grounds on the thermostat housing first. if they arent tight, the ecu will not power up.

 

I'm currently having an issue with no spark myself. Do a search for "no spark" in both the recent and archived threads, you'll find good info on things to check.

Some things to look at:

Fuses
Plugs
Wires
Battery
Distributor
Grounds

 

I did a rearch, but nothing and checked out everything..Strange this is the car had spark before...could it be the distributor has gone bad?