Plain Plug Gauge for Sleeve ID Go 6.603 to 6.605 Cyl. 0.001 Len. 80 to 81; with tapping of M4; NOGO 6.695 to 6.7 Cyl. 0.002 Len. 10 to 11 / Std. Gauging area should have lapped finish. Gauge No. PPG 6000.6700