Hi Team, recently my 3.8 snapped an inlet valve stem, dthus destroyong the piston and scoring the hea a little. Upon disassembly I found the pistons to have the standard "front" marking , but also 538 stamped in the top. I can find no reference to this...can someone help me out?

Stamped Number 538?

 

That's not a standard marking, my guess is the weight in grams when pistons were balanced during a previous rebuild.

 

Thanks, that is good thought, I shall investigate further.