HELP!!! 1997 Blazer 4.3 Timing Issues

I recently have completely rebuilt this engine. I am wanting to start it now and there seems to be a problem. I set both marks on the balancer right on spot with #1 at TDC. Put the rotor right on the number 6. I go to start and the motor clacks super loud (almost jamming sound) and wont start. The timing has to be off. I have checked my work over a dozen times. I have moved the rotor one tooth both ways. One way it clacks even louder and the other way it tries to fire every ten to twenty cranks but still bucks the engine. Any advice would be so helpful!!!

You set that distribitor with a scan tool and the timing is not adjustable.The distribtor has a cam sensor you do not screw up.Hook up a scan tool,programing it to the vehicle and go to the data stream looking for Cam sensor retard.The spec is 0 degrees if you want to know.

It sounds like your distributor is off by 180 degrese. You need to ensure that the #1 cylinder is at its highest point of the compression stroke. then aline your timing marks. Here is a great link for doing that. http://www.automotiveforums.com/vbulletin/showthread.php?t=881442&highlight=timing+marks
Post back on how you come out.