Timing setup 99 Silverado 4.3

I recently rebuild and re-installed my 4.3 into my silverado. Everything is hooked up, but it won't fire up. The distributor is aligned with TDC of cylinder #1, it was rechecked a couple times, but it still won't fire. Could the computer be getting in the way? Should I unplug the wire that goes into the bottom of the distributor? Thanks.

sparhawk56

The rotor should be pointing at a pointer cast into the distributor base with a 6 on it when the engine is at TDC on the compression stroke of cylinder #1.