KPMI, intake valve guide. Manganese. STD

Manganese bronze. Standard size dimensions: 0.5620" O.D. (14.27mm); 0.2750" I.D. (6.99mm); 2.02" OAL (51.31mm). Manganese bronze is softer and less durable then C630 bearing bronze but will allow a lower cost and reaming to size is quick and easy. Finish can be done with simple tools like a ball hone and an electric drill. Rapid heat transfer and excellent lubricity.