Forged Piston Noise when cold, Piston material or pin placement?

[Steven Holekamp <holekamp@xxxxxxx>]

In my limited experience I have not had any noisy pistons that had offset 
pin placement. But the 3 motors I have been involved with that did have 
this "knock" on startup were both forged pistons with centered pins. 2 of 
the 3 motors that made noise were over 10:1 compression(but had plenty of 
valve clearance and 0.050in head clearance). My old 360 and my brother's 
401 have forged pistons with slightly offset pins like factory pistons and 
neither ever made any noise like this, both of them had over 
0.003in.  piston clearance when new. All of these pistons are trw-speedpro 
4032 alloy, not the soft racing pistons.

Typically(and in all of the cases above) the offset pin is in pistons with 
4 valve reliefs and the centered ones have only 2 valve reliefs. Could it 
be related to chamber shape as well?

Food for thought......

Holekamp