20-21030 KPMI, exhaust valve guide. C630 bronze. STD

For high-performance 2017 to 2023 Milwaukee-Eight builds, these Kibblewhite C630 bronze exhaust valve guides are the gold standard. C630 is a tough nickel-aluminum-bronze alloy specifically engineered for racing and high-heat applications where moving heat from the valve to the cylinder head is a top priority. This is a standard size guide with a 0.4750 inch outside diameter and a 0.2342 inch inside diameter. Because the exhaust side sees the most thermal stress, the superior durability of C630 bearing bronze ensures your valvetrain stays stable under demanding conditions. Whether you are doing a standard service or a full performance build, these guides provide the precision and heat dissipation required for the modern Milwaukee-Eight engine.