KPMI, intake valve guide. Manganese bronze. STD

Maganese bronze. Standard size: 0.5650" O.D. (14.35mm); 0.3760" I.D. (9.55mm); 1.880" OAL (47.75mm). 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.