motor clatter??

[texasfunk]

well, just recently the motor has started a clatter, doesnt at idel, but it gets louder with acceleration, i took the valve covers off (revealing whoeverbuilt the motor put some good money into it, has guides, hardened welded pushrods, and roller rockers) and it seemed the push rods and rockers were all in good working order, then i noticed, the header on driver side(cant notice it on passenger side at all)is missing the back 3 bolts, could this be it? i know its the source of the small tick i have been hearing, but could it be the cause of the clatter?