Noisy xflow forged pistons

[Olgawld]

Hi. I've rebuilt my 1700 xflow with new accralite forged pistons. It's got a bit of a tapping, clackety sound most prevalent on idle. I understand with forged pistons they're slightly more undersize as they expand more when hot. Noise is still the same after 15/20 mins warming up. Do you think it's just the way the pistons are, nowt to worry about? Or could it be something else? I've checked and rechecked valve clearances, no exhaust or inlet leaks, that I can see/feel. Cheers. I've taken a video but can't see how to add to message.

[Roger King]

I can't tell you what the noise is, but Accralites don't normally make any unusual sounds cold or warm if they're running the correct clearance (around .0045" to .0055"). Are you certain that the valves aren't clashing with the piston pockets? It's a long time since I installed any Accralites but back in my day it was necessary to increase the diameter of the piston pockets if using valves much larger than std; they may have changed by now.