replaced head gasgets 1984 cressida now it wont start why

1. check the firing order of your plug wires, make sure they are 153624 2. check all vacuum lines for cracks or loose connections, disconnect the fuel line to make sure you have fuel coming through, never let people who may not be able to finish a job work on your car.

if your car backfires while trying to start it most likely your spark plugs are out of order

spark plug wires are out of order going from plug to distributor cap