2000 Chevy Cavalier Won't Start

Are the plug leads around the right way? i.e. in the right sequence? Did you put the distributor back in the way it was supposed to go? Did you engage the distributor gear on the right tooth?

Sounds like you may have not have had the cam/crank at the appropriate spots when you reassembled things.

In order to do the job properly you need to have the timing marks at the appointed places as defined in the manual. You cannot merely swap out the timing gear/chains where ever they stop.

It sounds like the timing of the cam is out and not in synch with the crank/pistons. if this is an "interference" style head then you may have "lunched" a valve or two.

The pop is the ignition firing with an inlet valve (partially)open. If you managed you get the plug wire order wrong on the distributor that will also lead to a pop and non running motor.

There are lots of other reasons why you may not be able to get it started related to doing the work you've done, but not really diagnosable over the interwebs.

Have you searched this forum for other cavalier threads?

Mods please make a Cavalier section in automotive and reassign all the thousands of cavalier threads to that. It'll help the Noobies out no end.

Why did you change it in the first place?

Sounds like Tobugrynbak has given a fair assessment.

If you aligned the camshaft and crankshaft correctly, you have the distributer 180 degrees out of time. Remember that the camshaft is only turning once to the crankshaft's two. Thus if the cam gear was turned from notch down to notch up, the distributer would not know that, and still be trying to fire the spark plug during the split overlap position.( both valves open at TDC.) Check the position of the rotor with the engine at TDC. If it is exactly pointing to, or exactly away from #1, just lift the distributer, and turn 180 and drop back in. To test if the valve timing is correct, do a compression test. If compression is good, valve timing is correct. No need to concern yourself with that. good luck.