Not Ranked
I talked to Ford Tech line. When Ford switched to the forged pistons, they lost some of the valve releif. The piston that Ford is using is made by Probe Industries. Tech line said this is the same shortblock that is used with the 475 HP 2.02 Z head. According to the tech they often do not have P/V clearance with the Z head on the motor with the forged pistons.
Anyway, I will let everyone know how this turns out.
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