I just finished changing out head gaskets and installed a cam as well. When it was first fired up it was backfiring every few seconds. For about 10 seconds there was no backfiring, then it went back to backfiring before it was turned off for the night (ran for about 30 seconds). Could this be some plug wires switched around? Could the rockers be adjusted to tightly? I will check the wires tomorrow, but I'm just getting ideas of what to check for tomorrow morning. I'm also positive the opti went on correctly.

 

I found the problem, The whole time I thought the passenger side wires were screwy, but of course it was the easiest to check driver side which were switched (#1 and 3). The car runs like a dream now.