my old head cracked, so I put a new Engnbldr fully assembled head on. It runs fine, but has a lot of valve tapping/slapping going on. I was always under the impression it will do this for about 400 miles as its "breaking in", and once they go through a good amount of heating cooling and change size, you would reset the valve lash and they should slap no more.

I just find it weird to have a brand new set of valves slapping into the top of my pistons, and it makes me kind of nervous in a way.

Should I back the valves off alittle? Or keep them as they are and just reset the lash after a good break in period?

 

Well, they probably aren't. But if they were, that ought to make you nervous. To say the least...If you're correct in diagnosing the noise as being valve lash related. Then they'd already be "backed off" too far. You would actually need to tighten them up a bit(as in decrease the valve lash/clearance). Because they make more noise when looser, and less noise when tighter.

FYI, neither too loose, nor too tight, is going to cause them to slap into the tops of the pistons.

 

hmm, okay, they're slapping into the block? I just figured I should open the gap up in the rockers alittle bit so they don't travel down so far and collide into whatever they collide with

 

Or will it eventually go away when the valves change sizes?

 

your valves will not be hitting anything at all unless you have your cam timing way off in which case the engine wont run, the noise you are more than likely hearing is the rocker arm hitting the valve stem because the gap is too big, its not going to hurt anything whilst the head is breaking in so just leave it and get someone to re-adjust your valve clearances after you have some miles on it