So I have this thing all together and now I have a
pretty scary knock only when the engine is cold. Sounds like a hard hammering best I can tell on the top end, but after a few minutes of idling it goes away and doesn't come back until the engine is cold again. I have rev'd it up over 4000 no problems once it's warm. Could it be a bad lifter or 2 or maybe I need to set preload again?

Any thoughts on what can cause this? can a bearing make that bad of a noise?