AMS Racing Armor Coated King Brand SI-Series Connecting Rod Bearings for Small Block Ford engines with Stock Crankshafts. King Bearings' bi-metal SI material blends Aluminum with 2.5-3% Silicon, providing strength. Ideal for medium-load engines, particularly engines using nodular cast iron crankshafts. It excels as a Lead-free OE replacement Bearing. AMS Armor Coating Details Our Armor Coating provides added protection against dry starts and oil starvation. By reducing bearing wear and flaking, we add an extra level of protection to the bearing. Due to the decreased friction, this also protects the bearings from heat build up.