AMPCO® 45 is a high strength alloy with mechanical properties that, due to its special manufacturing process, exceed the range of commercial nickel-aluminum bronzes. AMPCO® 45 is particularly useful in applications involving abrasive wear, friction, deformation, chemical erosion. This is why Eddie Rowe chose Ampco® 45 to make his premium Rowe USA Ampco® 45 valve guides.
Rowe USA Valve Guides
Rowe USA part numbers begin with a four digit code followed by the oversize (measured in thousandths of an inch). As seen on the chart a 1966 Shovelhead exhaust valve guide is 4501-00 for a standard replacement guide. 4501-02 would be .002 inch oversize on the outer diameter. A standard valve guide diameter is .5655 inch and the oversize would be .5675 inch. Oversize guides are designed to allow proper press fit. Distributors like Custom Chrome and V-Twin Mfg. created their own unique part numbers for Rowe USA guides. Since Rowe USA is out of business (2013) you will find a variety of obsolete inventory listed with different part number systems.
For more information on RoweUSA.us