KPMI, intake valve guide. C630 bronze. STD 1948-78

C630 bearing bronze. Standard size: 0.5650" O.D. (14.35mm); 0.3760" I.D. (9.55mm); 1.880" OAL (47.75mm). C630 bearing bronze is a tough nickel-aluminum-bronze alloy typically used in high performance and racing applications where rapid heat transfer from the valve to head is important.