Grinding, " diesel " noise under valve covers

Ironracer said

Much Appreciated Rob! I'm hoping it's piston slap or something else, besides a tore up.wrist pin, bad bearing, scuffed pistons,.ect...

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If it sounds like all eight and it greatly lessens when it gets hot, it's piston slap. If that's what it ends up being, with forged pistons, I wouldn't give a hoot and holler about it. Let it rattle.