1995 Dodge Avenger timing belt

Engine Mechanical problem
1995 Dodge Avenger 6 cyl Front Wheel Drive Automatic

I am working on a car for a friend. The timing belt broke and bent some vavles. I had a valve job done and reinstallled the heads. And acc. I installed the timing belt as instructed. I was also told that these are zero clearance valves. It says to line timing marks up on the cams. And to set at top dead center and then turn engine over counter clock wise three notches and then install the belt. I have dine this and still can not get the engine to run. I can get it to back fire but will not start?
thank you in advance
Dave
PS. I HAVE GOOD COMPRESSION