I've had lifters "hang-up" (not rotating in their bore) make a tickin/tappin sound. I've heard this about 318s for along time (hydraulic, non-roller lifters) When you start it you should let it get to operating temp. before shutting it off. I don't know how much truth is to it. but it seems to hold true for me. if the lifter don't rotate it will eventually wipe the lobe off the cam and ruin the lifter. i've had this happen with a built 318 with a "purple shaft" .484 in lift cam.

This is likely not your problem, but was wonderin if anybody else has dealt with or heard of this?